JP4886992B2 - Image processing apparatus, display apparatus, image processing method, and program - Google Patents

Description

  The present invention relates to an image processing device, a display device, an image processing method, and a program.

  In a display device, for example, when a white level high brightness pixel exists locally and a black level pixel exists around it for a long time, an adverse effect such as screen burn-in occurs. End up.

  As a conventional technique for suppressing the occurrence of such an adverse effect, for example, there is a technique disclosed in Patent Document 1.

As shown in FIG. 31, the display device disclosed in Patent Literature 1 includes an APL detection unit 101 that detects APL (Average Picture Level: average value data of luminance levels) of an image signal, and detection from the APL detection unit 101. A luminance control unit 102 that controls (corrects) luminance according to a signal and a plasma display panel 103 that displays an image using an image signal from the luminance control unit 102, and the luminance control unit 102 has a range of APL values Is configured to perform luminance control when the value continues for a certain time.
JP 2000-305514 A

  However, in the above-described prior art, since the APL is detected and the average luminance of the entire screen is detected, the reduction effect such as screen burn-in is not sufficient. That is, for example, it is impossible to determine whether the screen has a large number of white level pixels or not. For example, most of the pixels on the screen, such as a clock display, have a black level, and only a few white level pixels. When there is no video, it cannot be detected and the brightness cannot be corrected.

  The present invention has been made in order to solve the above-described problems. An image processing apparatus, a display apparatus, an image processing method, and a program that can reduce adverse effects such as image sticking more preferably. The purpose is to provide.

In order to solve the above problems, an image processing apparatus according to the present invention is an image processing apparatus that performs image processing on an image displayed on a display screen . Luminance level distribution detecting means for detecting a statistical distribution of the number of pixels based on the input image signal, and luminance for correcting the luminance level of the input image signal in accordance with the number of pixels for each luminance level detected by the luminance level distribution detecting means Correction means, and the luminance level distribution detection means includes at least a black level composed of a plurality of low gradations including a minimum gradation, a white level composed of a plurality of high gradations including a maximum gradation, and those A statistical distribution of the number of pixels for each of the three luminance levels of the intermediate level consisting of the number of gradations between, and the luminance correction means, the number of pixels for each of the three luminance levels, the three luminance The luminance level of the input image signal is corrected according to the magnitude relationship between the number of pixels of the level and the number of pixels of a specific luminance level among the luminance levels included in the white level, and the specific luminance level is In the statistical distribution of the number of level pixels, the luminance level is such that the number of pixels reaches a peak .

In the image processing apparatus according to the aspect of the invention, the brightness correction unit may include a first condition that the number of pixels of the white level is larger than a first threshold value and smaller than a second threshold value; The second condition that the number of pixels at the intermediate level is smaller than a third threshold value, the third condition that the number of pixels at the black level is larger than the intermediate level, and the black level than the white level. The fourth condition that the number of level pixels is large is satisfied when the condition D is satisfied, the fifth condition that the number of black level pixels is larger than a fourth threshold value, The sixth condition that the number of pixels of the intermediate level is larger than the fourth threshold value is satisfied, and among the luminance levels included in the white level, the specific luminance level The number of pixels is less than the fifth threshold When the condition E is satisfied when the seventh condition of threshold is satisfied, the third threshold value is larger than the second threshold value and smaller than the fourth threshold value, The fifth threshold value is larger than the second threshold value and smaller than the third threshold value, and when the condition D or the condition E is satisfied, the luminance level of the input image signal It is preferable not to correct the luminance level of the input image signal when neither of the condition D and the condition E is satisfied .

In the image processing apparatus of the present invention, the luminance correction unit may be configured to output the input image signal when the statistical distribution of the luminance level is a distribution that is a correction target of the luminance level for a longer time than a predetermined time. It is preferable to correct the luminance level.
The luminance correction unit, by reducing the luminance of the input image signal, or, it is preferable to perform the correction by lowering the luminance of the pixels of the white level.
Alternatively, the luminance correction means, among luminance levels included in the white level, it is possible to perform the correction by lowering the luminance of the pixels of a particular brightness level.

  According to the present invention, a luminance level distribution detecting unit that detects a statistical distribution for each luminance level of pixels included in an image based on an input image signal, and the input according to the statistical distribution detected by the luminance level distribution detecting unit. And a luminance correction unit that corrects the luminance level of the image signal. Therefore, it is possible to suppress the occurrence of adverse effects such as image burn-in more suitably than before, and to improve the image quality.

  Specifically, for example, the white level ratio can be detected by the brightness level distribution detecting means, and the brightness can be corrected by the brightness correcting means when the white level ratio is large.

  In addition, for example, when displaying an image in which almost all pixels on the screen are at a black level and there are only a few pixels at a white level, such as a clock display, this can be detected and the luminance can be corrected.

  According to the present invention, the luminance level distribution detecting step for detecting the statistical distribution for each luminance level of the pixels included in the image based on the input image signal, and the statistical distribution detected by the luminance level distribution detecting step And a luminance correction step for correcting the luminance level of the input image signal. Similarly, it is possible to suppress the occurrence of adverse effects such as screen burn-in more suitably than before, and to improve the image quality. it can.

  Further, according to the present invention, the image dividing means for dividing the image to be displayed by the input image signal into a plurality of parts, the image combining means for combining the images after the division by the image dividing means, and the image dividing means Non-linear processing means for performing non-linear processing on at least one of the images after the division and before the synthesis by the image synthesizing means, and a first operation mode for correcting the luminance level by the luminance correction means And a second operation mode for performing image processing by the image dividing unit, the image synthesizing unit, and the nonlinear processing unit, and an operation mode selecting unit for selecting one of the operation modes. If, for example, a part of an image to be displayed by one input image signal is an image that tends to cause screen burn-in, a part of the image is displayed. On the other hand, by applying a nonlinear process that reduces the difference between light and dark in the image, the image burn-in can be reduced. On the other parts of the image, a nonlinear process that provides normal brightness is performed. It can be displayed so as to have normal brightness by applying or not performing non-linear processing. In addition, when displaying an image for which white is to be emphasized on a part of the display screen and displaying a dark image on the other part, non-linear processing is applied to the dark image so as to increase the number of gradations. The dark image can be clearly seen.

  Embodiments according to the present invention will be described below with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram illustrating a configuration of a display device 100 according to the first embodiment.

  As shown in FIG. 1, the display device 100 according to the present embodiment performs a brightness correction process on an input image signal (hereinafter referred to as an input image signal) to reduce burn-in on the display screen. (Image processing apparatus) 10 and a display unit that receives an image signal that has been corrected or not corrected by luminance correction unit 2 (described later) of burn-in reduction unit 10 and displays an image based on the input image signal 20.

  Among these, the burn-in reduction unit 10 includes a histogram detection unit (luminance level distribution detection unit) 1 that detects a statistical distribution for each luminance level of pixels included in an image based on an input image signal, and the histogram detection. An image signal is input via the unit 1, a luminance correction unit 2 that corrects the luminance level of the image signal as necessary, and a microcomputer 4 (hereinafter referred to as data relating to the statistical distribution detected by the histogram detection unit 1). , And abbreviated as microcomputer 4).

  The microcomputer 4 and the luminance correction unit 2 constitute luminance correction means.

  The microcomputer 4 includes a CPU and a memory, and a CPU control program is stored in the memory. The CPU and the microcomputer 4 operate according to this program.

  In the present embodiment, the display device 100 is a plasma display device including a plasma display panel as the display unit 20, for example.

  In the case of this embodiment, the histogram detection unit 1, for example, for an image displayed on the entire display screen (one display screen) of the display unit 20, a statistical distribution for each luminance level of the pixels included in the image (hereinafter, (Luminance level distribution) is detected.

  More specifically, the histogram detection unit 1 is configured to count the number of pixels for each luminance level, obtain a statistical distribution of the counted number of pixels, and form a histogram.

  More specifically, the histogram detection unit 1 is configured to detect a statistical distribution of the number of pixels for each of three luminance levels, for example, a black level, a white level, and an intermediate level thereof, and form a histogram.

  That is, for example, as shown in FIGS. 3 to 9, the histogram detection unit 1 displays the histogram as (1) black level area (black level), (2) intermediate level area (intermediate level), and (3) white level area. The area is divided into three (white level) luminance levels, the total number of pixels in each area is counted, and a histogram is formed.

  Here, the line graphs shown in FIG. 3 to FIG. 9 are the number of pixels for each luminance level, and the sum of the number of pixels of the luminance level included in each of the areas (1) to (3) above. Are represented as histograms in each figure.

  In FIG. 2B and FIGS. 3 to 9, the area on the right side has a higher luminance and the area on the left side has a lower luminance.

  For example, as shown in FIGS. 3 to 9, when the number of gradations of the luminance level is 256 from 0 to 255, 86 gradations of luminance levels 0 to 85 are included in (1) the black level area, and the luminance level 85 gradations of 86 to 170 may be included in (2) the intermediate level area, and 85 gradations of luminance levels 171 to 255 may be included in (3) the white level area.

  Further, for example, as shown in FIG. 2B, the histogram detection unit 1 further subdivides the luminance levels included in the areas (1) to (3), and the number of pixels for each subdivided luminance level. It is also possible to detect the distribution of and to form a histogram.

  Here, (1) black level, (2) intermediate level, and (3) white level are the total number of pixels obtained by dividing 0 to 1024 (in the case of a digital 10-bit signal) within the luminance level range of the image signal into three. The following relational expression holds for the total number of pixels at each level.

(1) Total number of pixels included in the black level + (2) Total number of pixels included in the intermediate level + (3) Total number of pixels included in the white level = Total number of pixels included in one display screen (resolution) (for example, (In the case of VGA: 640 × 480 = 307200)
The histogram detection unit 1 transmits the brightness level distribution data detected as described above (hereinafter, brightness level distribution data) to the microcomputer 4.

  Further, the microcomputer 4 determines whether or not there is a possibility that image sticking will occur on the display screen of the display unit 20 according to the luminance level distribution data from the histogram detection unit 1, and determines that there is a possibility that image sticking will occur. In this case, control data is transmitted to the luminance correction unit 2 in order to perform a luminance level correction operation.

  Here, (1) the total number of pixels included in the black level, (2) the total number of pixels included in the intermediate level, and (3) the total number of pixels included in the white level are simply (1) and (2 ) And (3), the determination as to whether or not the luminance level is to be corrected is performed using a condition of any one or a combination of the following A, B, and C as a determination criterion.

  A... Performed according to the values of (1), (2) and (3) (according to the number of pixels for each of the three luminance levels of the black level, the white level and their intermediate levels, the input image signal Correct the brightness level).

  B... (1), (2), and (3) are performed according to the magnitude relationship (in accordance with the magnitude relationship between the number of pixels of the three luminance levels of the black level, the white level, and the intermediate level thereof) The luminance level of the input image signal is corrected).

  C: Performed according to the value of the number of pixels of a specific luminance level (gradation) in the white level (hereinafter simply referred to as (4)).

  In the case of this embodiment, more specifically, for example, the following conditions D and E are used as a criterion for determining whether or not to correct the luminance level.

<Condition D>
As shown in FIG. 5, the condition D includes a first condition “first threshold value a <(3) <second threshold value b” and “(2) <third threshold value”. This is satisfied when the second condition “c”, the third condition “(1) >> (2)”, and the fourth condition “(1) >> (3)” are all satisfied.

  Here, for example, the second threshold value b <the third threshold value c is established.

  Further, (1) >> (2) specifically means, for example, the case where (1) is twice or more or three times or more of (2).

  Further, (1) >> (3) specifically means, for example, a case where (1) is twice or more or three times or more of (3).

<Condition E>
As shown in FIG. 4, the condition E includes a fifth condition “(1)> fourth threshold value d” and a sixth condition “(2)> fourth threshold value d”. Is satisfied when one of the above is satisfied and the seventh condition of “(4)> fifth threshold value e” is satisfied.

  Here, for example, the third threshold value c <the fourth threshold value d is satisfied.

  Further, for example, the second threshold value b <the fifth threshold value e <the third threshold value c is satisfied.

  The microcomputer 4 may cause screen burn-in when the state determined to apply to the condition D or E continues for a predetermined time α (for example, 30 seconds or 1 minute) in total. It is determined that there is, and control data is transmitted to the luminance correction unit 2 in order to perform the luminance level correction operation.

  On the other hand, in the case of FIGS. 3, 6, 7, 8, and 9 that do not apply to either the condition D or the condition E, and the condition D or the condition E, the state continues for less than the predetermined time α. If not, it is determined that there is no possibility of image sticking and the brightness level is not corrected.

  When the luminance level distribution shown in FIG. 4 that satisfies the condition E is subdivided, a luminance level distribution similar to that shown in FIG. 2B is obtained. The brightness level distribution shown in FIG. 2B is, for example, a screen display in which almost the entire screen is dim as shown in FIG. 2A and a white clock display with high brightness is made in the upper right corner. Obtained in the case of. If the screen display state as shown in FIG. 2A continues, there is a possibility that the screen will be burned. In this case, in the luminance level distribution detected by the histogram detector 1, as shown in FIG. 2B, while (1) is relatively large, a prominent peak is seen in (4).

  Further, the luminance level distribution shown in FIG. 5 that applies to the condition D is obtained in the case of a screen display in which there are many (1) and (3) to some extent, although there is no peak that was in the case of (4). In such a case as well, as in FIG. 4, there is a possibility that screen burn-in may occur, so the luminance level is corrected.

  As shown in FIG. 3, when (2) is large and (1) and (3) are both small, as shown in FIG. 6, (3) is large but (1) is small, as shown in FIG. When (1) to (3) are about the same, as shown in FIG. 8, (1) and (3) are slightly more than (2), but (1) and (3) are about the same As shown in FIG. 9, when (3) is small and there is no peak of (4), it is determined that there is no possibility of image sticking because there is not much possibility of image sticking. However, the brightness level is not corrected.

  As described above, the microcomputer 4 transmits control data to the luminance correction unit 2 for correcting the luminance level when the number of pixels of the white level is a certain value or more.

  In addition, when the control data is transmitted from the microcomputer 4 for correcting the brightness level, the brightness correction unit 2 corrects the brightness level of the input image signal input via the histogram detection unit 1.

  Here, the correction by the luminance correction unit 2 is performed, for example, by reducing the luminance level of white level pixels to be corrected (for example, all the pixels in (3) uniformly) by a predetermined ratio. .

  Specifically, this correction may be performed by, for example, reducing the luminance of a white level pixel to 70% or less (specifically, for example, 70%) (that is, reducing it by 30%). Alternatively, the correction may be performed by reducing the luminance of the white level pixel to 50% or less (specifically, for example, 50%) (that is, reducing the luminance by 50%).

  Alternatively, it is also preferable to reduce the luminance of a specific pixel among the pixels of the white level, that is, the pixel at the luminance level near the white peak in (4). Specifically, this correction is also performed by, for example, reducing the luminance of the pixel at the luminance level near the white peak in (4) to 70% or less (specifically, for example, 70%) or 50%. Performing by lowering to the following (specifically, for example, 50%) can be mentioned.

  Alternatively, it is also preferable to reduce the luminance of only the pixels having the luminance level of the white peak (4). This correction is also specifically performed by, for example, reducing the luminance of the corresponding pixel to 70% or less (specifically, for example, 70%) or 50% or less (specifically, for example, 50%).

  Here, the correction by the luminance correction unit 2 is performed by gradually changing the maintenance frequency of the display unit 20 so as not to make a person watching the display screen of the display unit 20 feel that the luminance correction is being performed.

  Further, the luminance correction unit 2 is an input image signal that has been corrected as necessary in this manner (the input image signal that has been corrected when it is determined that screen burn-in may occur, If it is determined that there is no possibility of screen burn-in, the input image signal is not corrected) and is transmitted to the display unit 20.

  The display unit 20 performs image display based on the input image signal from the luminance correction unit 2 on the display screen (not shown).

  Next, the operation of the microcomputer 4 will be described with reference to the flowchart of FIG.

  Note that the process shown in FIG. 10 is a process repeatedly performed by the microcomputer 4 at predetermined intervals.

  First, in step S1, it is determined whether or not the first condition “first threshold value a <(3) number of white level pixels <second threshold value b” is satisfied.

  If it is determined that the first condition is satisfied (YES in step S1), the process proceeds to step 2, and is the second condition “(2) number of intermediate level pixels <third threshold value c” satisfied? Determine whether or not.

  When it is determined that the second condition is satisfied (YES in step S2), the process proceeds to step S3, and the third condition “(1) number of black level pixels >> (2) number of intermediate level pixels” is satisfied. It is determined whether or not.

  If it is determined that the third condition is satisfied (YES in step S3), the process proceeds to step S4, and the fourth condition “(1) number of black level pixels >> (3) number of white level pixels” is satisfied. It is determined whether or not.

  When it is determined that the fourth condition is satisfied (YES in step S4), that is, when it is determined that all the first to fourth conditions are satisfied, the process proceeds to step S5.

  In addition, said step S1-S4 is the process of determining whether said condition D is applied.

  In step S5, the timer count value is incremented by "1".

  In a succeeding step S6, it is determined whether or not the count value of the timer is larger than a value corresponding to a predetermined time α (for example, 30 seconds or 1 minute).

  If it is determined that the count value of the timer is greater than the value corresponding to the predetermined time α (YES in step S6), the process proceeds to step S7, where it is determined that there is a possibility of screen burn-in and brightness correction is performed. In order to achieve this, the control data is transmitted to the luminance correction unit 2, and the processes after step S1 are repeated again.

  On the other hand, if it is determined in step S6 that the count value of the timer is not greater than the value corresponding to the predetermined time α (NO in step S6), there is a possibility that the process proceeds to step S12 to cause screen burn-in. It is determined that there is no brightness control, and the process after step S1 is repeated again without performing brightness control (without transmitting control data to the brightness correction unit 2).

  Further, when it is determined that any one of the first to fourth conditions is not satisfied (NO in any of steps S1 to S4), that is, when the above condition D is not satisfied. The process proceeds to step S8.

  In step S8, it is determined whether or not the fifth condition “(1) number of pixels of black level> fourth threshold value d” is satisfied.

  When it is determined that the fifth condition is satisfied (YES in step S8), the process proceeds to step S9, and a seventh "(4) number of pixels at a specific level among white levels> fifth threshold value e" is set. It is determined whether the condition is satisfied.

  When it is determined that the seventh condition is satisfied (YES in step S9), that is, when it is determined that both the fifth condition and the seventh condition are satisfied, the process proceeds to step S5. The processing after step S5 is the same as described above.

  On the other hand, if it is determined in step S9 that the seventh condition is not satisfied (NO in step S9), the process proceeds to step S11, the timer count value is reset (set to "0"), and the step The process proceeds to S12, where it is determined that there is no possibility of image burn-in, and the processing after step S1 is repeated again without performing luminance control.

  If it is determined in step S8 that the fifth condition is not satisfied (NO in step S8), the process proceeds to step S10, and “(2) number of intermediate level pixels> fourth threshold value d”. Whether the sixth condition is satisfied is determined.

  When it is determined that the sixth condition is satisfied (YES in step S10), the process proceeds to step S9, and the seventh condition “(4) Number of pixels at a specific level among white levels> fifth threshold value e” is set. It is determined whether the condition is satisfied.

  When it is determined that the seventh condition is satisfied (YES in step S9), that is, when it is determined that both the sixth condition and the seventh condition are satisfied, the process proceeds to step S5. The processing after step S5 is the same as described above.

  If it is determined in step S10 that the sixth condition is not satisfied (NO in step S10), the process proceeds to step S11, and the processing after step S11 is performed in the same manner as described above.

  The steps S8 to S10 are processes for determining whether or not the above condition E is satisfied.

  As described above, according to the first embodiment, the histogram detection unit 1 that detects the statistical distribution for each luminance level of the pixels included in the image based on the input image signal, and the statistical distribution detected by the histogram detection unit 1 Since the microcomputer 4 and the luminance correction unit 2 as luminance correction means for correcting the luminance level of the input image signal according to the above are provided, it is possible to reduce burn-in more suitably than before and improve the image quality. Can do.

  Specifically, for example, the histogram detection unit 1 can detect the ratios of the luminance levels (1) to (3). For example, when the ratio of the white level of (3) is large, the luminance can be reduced. It can be corrected. In addition, for example, when displaying an image in which almost all pixels on the screen are at a black level and there are only a few pixels at a white level, such as a clock display, this can be detected and the luminance can be corrected.

  In particular, since the luminance level distribution can be expressed as a histogram by the histogram detection unit 1, the luminance can be corrected appropriately.

  In addition, by performing luminance correction in this way, a secondary effect that power consumption can be suppressed can be obtained.

<Modification>
FIG. 11 is a block diagram illustrating a configuration of a display device 150 according to a modification of the first embodiment.

  The display device 150 shown in FIG. 11 differs from the display device 100 according to the first embodiment only in that it further includes a timer 5, and is otherwise configured in the same manner as the display device 100. In 150, the same code | symbol is attached | subjected to the component similar to the display apparatus 100, and the description is abbreviate | omitted.

  In the first embodiment, the example in which the predetermined time α is counted by adding the count value in the microcomputer 4 has been shown. However, for example, a timing operation is performed as in the display device 150 shown in FIG. Further, a timer 5 (timer IC) for giving the time measurement data to the microcomputer 4 may be further provided, and the microcomputer 4 may monitor the progress of the predetermined time α based on the time measurement data from the timer 5. In this case, the microcomputer 4, the timer 5, and the brightness correction unit 2 constitute a brightness correction unit.

[Second Embodiment]
In the first embodiment, the example in which the brightness level distribution is detected for the entire display screen and the brightness level is corrected has been described. However, in the second embodiment, a part of the display area of the display screen is displayed. An example in which the luminance level distribution is detected and the luminance level in the display area is corrected will be described.

  12 and 13 are diagrams for explaining the operation in the case of the second embodiment. FIG. 12A shows an example of an image displayed on the screen, and FIG. 12B shows an image. FIG. 12A shows a luminance level distribution in the form of a histogram when FIG. FIG. 13A shows another example of an image displayed on the screen, and FIG. 13B shows a histogram-like luminance level distribution when the image is FIG. 13A.

  In the second embodiment, the configuration of the display device 100 is the same as that of the first embodiment.

  For example, clock display and channel display are often performed at the corner of the screen (for example, the upper right corner).

  Therefore, in the present embodiment, as shown in FIGS. 12 and 13, the histogram detection unit 1 detects the luminance level distribution only for the display region R of a part of the display image (for example, the upper right corner).

  In the case of the present embodiment, the microcomputer 4 satisfies, for example, the condition F that “only the number of pixels at a specific luminance level among the luminance levels included in the white level is equal to or greater than the fifth threshold value e”. If it is determined that it is satisfied, the luminance level is corrected. This makes it easier to detect clock display, channel display, and the like at the corners of the screen, and the brightness level can be corrected to prevent burn-in in such a case.

  As illustrated in FIG. 12A, since time is displayed at a white level in the upper right corner of the screen, it is considered that there is a high possibility that the screen will be burned. In such a case, as shown in FIG. 12B, the luminance level is corrected to satisfy the condition F.

  On the other hand, as illustrated in FIG. 13A, in the case of an image display in which the left side of the screen is missing from the right side and the screen gradually changes from a dark screen to a bright screen, the possibility of screen burn-in is low. it is conceivable that. In such a case, as shown in FIG. 13 (b), not only the number of pixels at a specific luminance level among the luminance levels included in the white level, but also the number of pixels at other luminance levels included in the white level. Since the threshold value e is 5 or more, the condition F is not satisfied, and the luminance level is not corrected.

  As described above, according to the second embodiment, a part of the display area R of one display screen is specified, the luminance level distribution is detected for the display area R, and the luminance level in the display area R is corrected. Therefore, for example, image sticking due to a clock display or channel display can be suitably reduced.

  In the second embodiment described above, correction is performed when only the number of pixels of a specific luminance level among the luminance levels included in the white level is equal to or greater than the fifth threshold value e, as shown in FIG. As described above, an example in which correction is not performed when not only the number of pixels at a specific luminance level but also the number of pixels at other luminance levels included in the white level is equal to or greater than the fifth threshold value e has been described. In any case, correction is simply performed when “the number of pixels of a specific luminance level among the luminance levels included in the white level is equal to or greater than the fifth threshold value e”, as shown in FIG. The correction may be performed not only in such a case but also in the case shown in FIG.

[Third Embodiment]
FIG. 14 is a block diagram illustrating a configuration of a display device 300 according to the third embodiment.

  In each of the above embodiments, an example in which only one histogram detection unit 1 is provided has been described. In the third embodiment, an example in which a plurality of histogram detection units 1 and 1A are provided as illustrated in FIG. 14 will be described. .

  The display device 300 according to the third embodiment is different from the display device 100 according to the first embodiment only in the points described below, and the display device 100 according to the first embodiment is otherwise different. Therefore, in the display device 300 according to the third embodiment, the same components as those of the display device 100 are denoted by the same reference numerals, and the description thereof is omitted.

  That is, in the case of the present embodiment, for example, as shown in FIG. 14, the front-stage histogram detection unit (first brightness level distribution detection unit) 1 detects the brightness level distribution for the entire display screen, and The histogram detector 1A (second luminance level distribution detecting means) detects the luminance level distribution for a part of the display area R (see FIG. 12) of one display screen.

  In addition, the microcomputer 4 determines whether the luminance correction unit is a luminance correction unit when the luminance level distribution detected by any one of the histogram detection units 1 and 1A satisfies any one of the above conditions (for example, the conditions D, E, and F). The control data is transmitted to 2, and the brightness level is corrected.

  As described above, according to the third embodiment, by using two ICs (histogram detectors 1 and 1A) capable of detecting a histogram, histogram detection using a part of the display image and histogram detection using the entire display image can be performed simultaneously. By doing so, it is also possible to grasp the position information of each luminance level of the display image.

  In the third embodiment, the example in which the two histogram detection units 1 and 1A are provided has been described. However, the present invention is not limited thereto, and three or more histogram detection units are provided, which are different from each other. The luminance level distribution may be detected for a plurality of display areas (however, overlapping portions may exist). In addition, luminance level distribution detection for a plurality of display areas that are different from each other as described above may be performed by one histogram detection unit.

[Fourth Embodiment]
FIG. 15 is a block diagram illustrating a configuration of a display device 400 according to the fourth embodiment.

  In each of the above embodiments, the example in which the histogram detection unit 1 detects the luminance level distribution only for one predetermined display area has been described. However, in the fourth embodiment, the display area that is a detection target of the statistical distribution. An example of sequentially changing will be described.

  The display device 400 according to the fourth embodiment is different from the display device 150 (FIG. 11) according to the modified example of the first embodiment only in the points described below, and the display device 150 in other points. Therefore, in the display device 400 according to the fourth embodiment, the same components as those of the display device 150 are denoted by the same reference numerals, and the description thereof is omitted.

  That is, in the case of the present embodiment, for example, as shown in FIG. 15, the display device 400 includes a storage unit 6 that stores display area designating data that designates a display area in which luminance level distribution should be detected in an image, and includes histogram detection. The unit 1 reads the display area designation data from the storage unit 6 and detects the luminance level distribution for the display area designated by the display area designation data. In addition, the microcomputer 4 sequentially changes the display area to be detected by the histogram detection unit 1 for the luminance level distribution by sequentially rewriting the display area designation data in the storage unit 6.

  In the case of the present embodiment, the microcomputer 4 and the storage unit 6 constitute detection area changing means, among which the microcomputer 4 constitutes designated data rewriting means, and the storage part 6 constitutes storage means.

  Next, the operation in the present embodiment will be described with reference to the flowchart of FIG.

  First, the microcomputer 4 designates, for example, the entire display screen as a display area that is a detection target of the luminance level distribution (step S11). That is, the display area designating data in the storage unit 6 is used to designate the entire display screen.

  Then, the histogram detection unit 1 reads the display area designation data from the storage unit 6, detects the luminance level distribution for the display area designated by the read display area designation data, that is, the entire display screen, and the detection result Is transmitted to the microcomputer 4.

  Then, the microcomputer 4 satisfies the condition G that the luminance level distribution detected by the histogram detection unit 1 satisfies the above condition (for example, the conditions D, E, and F) for at least the predetermined time α. It is determined whether or not it is satisfied (step S12).

  If the microcomputer 4 determines that the condition G is satisfied (YES in step S12), the microcomputer 4 transmits control data to the luminance correction unit 2 to correct the luminance level (step S13).

  If it is determined in step S12 that the condition G is not satisfied (NO in step S12), or after correction of the luminance level (step S13), the microcomputer 4 displays the display area that is the detection target of the luminance level distribution. Is changed to display areas obtained by dividing the entire screen into two, the display area designation data in the storage unit 6 is rewritten (step S14).

  Then, the histogram detection unit 1 detects the luminance level distribution for the display area designated by the display area designation data, that is, each display area obtained by dividing the entire screen into two, and transmits the detection result to the microcomputer 4.

  Then, the microcomputer 4 determines whether or not the condition G is satisfied in any of the display areas divided into two (step S15).

  If the microcomputer 4 determines that the condition G is satisfied (YES in step S15), the microcomputer 4 transmits control data to the luminance correction unit 2, and the luminance level in the display area that satisfies the condition G in the two divided display areas. Is corrected (step S16).

  If it is determined in step S15 that the condition G is not satisfied in any of the display areas divided into two (NO in step S15), or after correcting the luminance level (step S16), the microcomputer 4 Then, the display area designation data in the storage unit 6 is rewritten so that the display area that is the detection target of the luminance level distribution is each display area obtained by dividing the entire screen into four (step S17).

  Then, the histogram detection unit 1 detects the luminance level distribution for each display area obtained by dividing the entire screen into four parts, and transmits the detection result to the microcomputer 4.

  Then, the microcomputer 4 determines whether or not the condition G is satisfied in any of the display areas divided into four (step S18), and if satisfied (YES in step S18), transmits the control data to the luminance correction unit 2. The luminance level in the display area that satisfies the conditions is corrected (step S19).

  In step S18, if the condition G is not satisfied in any of the four divided display areas (NO in step S18), or after correcting the luminance level (step S19), the microcomputer 4 again Then, the display area that is the detection target of the luminance level distribution is returned to the entire screen (repetition from step S11).

  Thereafter, in the same manner as described above, the display area to be detected for the luminance level distribution is set as follows: the entire screen → each display area obtained by dividing the entire screen into two → each display area obtained by dividing the entire screen into four → the entire screen. Repeat in order.

  As described above, according to the fourth embodiment, the display area that is the detection target of the luminance level distribution by the histogram detection unit 1 is sequentially changed. Even if it is displayed in the display area, it is possible to detect this and correct the luminance.

  In the fourth embodiment, as the process of detecting the luminance level distribution, the process of detecting the entire screen, the process of detecting each display area obtained by dividing the entire screen, and the entire screen are divided into four. Although the example which performs the process of detecting about each display area was demonstrated, furthermore, the process of detecting about each display area which divided the whole screen into 8, the process of detecting about each display area which divided the whole screen into 16 ... -May be sequentially performed.

  In the fourth embodiment, the example in which the luminance level distribution detection is performed in parallel for each of the plurality of display areas (two divisions, four divisions) has been described. The luminance level distribution detection for each display area may be performed sequentially. That is, for example, when the display areas of the first and second display areas divided into two are targeted for detection, first, the luminance level distribution of the first display area is detected, and then the second luminance level is detected. It is possible to detect the distribution.

  Also, in each of the above embodiments, the example in which the luminance level distribution is detected by making it into a histogram has been described, but the point is that it is only necessary to recognize the statistical distribution of the luminance level, and other statistical graphs may be detected. good.

[Fifth Embodiment]
FIGS. 17 and 18 are diagrams for explaining the correction by the luminance correction unit 2 in the case of the fifth embodiment. FIG. 17A shows a display area R2 around the white level display area R1. FIG. 17B is a diagram showing a screen display in the case of all black (the luminance level of all the pixels in the display region R2 is 0 gradation). FIG. 17B shows the display region R2 around the white level display region R1 being all white. FIG. 18 is a diagram showing screen display when the luminance level of all the pixels in the display region R2 is 255 gradations. FIG. 18 is an example of a correction curve (curve) used for luminance level correction in the fifth embodiment. It is a figure which shows L2).

  In each of the above embodiments, as correction by the luminance correction unit 2 when it is determined that correction is necessary by the microcomputer 4, for example, the luminance level of a specific pixel among white level pixels or white level pixels is An example has been described in which, regardless of the manner of luminance level distribution of surrounding pixels, it is reduced by a certain ratio (for example, 70% or 50% (reduced by 30% or 50%)).

  However, in general, in the display of the pixels of the white level, the luminance level distribution of the surrounding pixels is closer to all black (the average video level; APL is smaller), while the luminance is higher, while it is closer to all white ( The control is performed such that the luminance is lower as the APL is larger. This is because if the brightness correction is not performed in this way, the contrast ratio decreases and the display image quality deteriorates on a dark screen where the APL of the video signal is small. This is because the difference in power consumption between when the voltage is large and when the voltage is small is large, which causes a problem that the burden on the power supply increases.

  In order to solve such a problem, for example, as shown in FIG. 17A, when the display area around the white level display area R1 is all black, as shown in FIG. In the case where the display area R2 around the white level display area R1 is all white, control is usually performed to display the former with higher brightness even when the white level display is the same level.

  That is, normally, the luminance level of the white level pixel is controlled according to, for example, the curve L1 shown in FIG.

  However, when such control is performed, there is a problem in that, for example, in the state of the luminance level distribution as shown in FIG.

  Therefore, in the fifth embodiment, as the correction by the luminance correction unit 2 when the microcomputer 4 determines that correction is necessary, the luminance level of the white level pixel is set, and the luminance level distribution of the surrounding pixels is low. The correction is made so that the level distribution is decreased at a higher rate as the level distribution is obtained.

  That is, the brightness correction unit 2 specifically performs correction under the control of the microcomputer 4 so as to control the brightness level of the white level pixels according to the curve L2 shown in FIG.

  Accordingly, for example, as shown in FIG. 17A, the luminance level distribution state in which the display region R2 around the white level display region R1 is all black, or a luminance level distribution state close to this. In addition, it is possible to make it difficult for image sticking to occur.

  According to the fifth embodiment as described above, the luminance correction unit 2 reduces the luminance level of the pixel to be corrected at a higher rate as the luminance level of the surrounding pixels is lower. Since the correction is performed, the image sticking can be reduced more suitably than the above-described embodiments.

[Sixth Embodiment]
FIG. 19 is a block diagram showing a configuration of a display device 600 according to the sixth embodiment.

  The display device 600 shown in FIG. 19 is different from the display device 100 according to the first embodiment only in the points described below, and is configured in the same manner as the display device 100 in other points. In the figure, the same components as those of the display device 100 are denoted by the same reference numerals, and the description thereof is omitted.

  In each of the above embodiments, an example of correcting the luminance level for the image signal has been described. However, the display device 600 according to the sixth embodiment corrects the luminance level for the image signal, performs nonlinear processing on the image signal, One of these is performed alternatively.

  In order to realize such an operation, the burn-in reduction unit 10 of the display device 600 includes, in addition to the components of the burn-in reduction unit 10 in the display device 100 according to the first embodiment, as shown in FIG. An image dividing unit (image dividing unit) 30 that divides the image into a plurality of parts, and a gamma processing unit (nonlinear processing unit) that individually performs gamma processing as an example of nonlinear processing on each of the divided images. 40, an image synthesis unit (image synthesis unit) 50 that synthesizes the image after gamma processing, a two-dimensional low-pass filter (border part image processing unit) 60 for smoothing the boundary between the images to be synthesized, A first operation mode for outputting an image signal whose luminance level has been corrected by the luminance correction unit 2 for display, an image dividing unit 30, a gamma processing unit 40, a two-dimensional low-pass filter 60, and an image; And a second operation mode to output for display a video signal on which the image processing has been performed by the generating unit 50, a switching unit 7 for switching the is further equipped with configure.

  Among these, the switching unit 7 switches to one of the first operation mode and the second operation mode, for example, under the control of the microcomputer 4. For example, the microcomputer 4 outputs a control signal to the switching unit 7 in response to a user operation on an operation unit (not shown), and switches the switching unit 7 to the first operation mode or the second operation mode. Make it. That is, the microcomputer 4 and the switching unit 7 constitute an operation mode selection unit.

  An input image signal to the burn-in reduction unit 10 is input to the switching unit 7. The switching unit 7 outputs the input image signal to the histogram detection unit 1 when the operation mode is switched to the first operation mode, while the input image signal when the operation mode is switched to the second operation mode. Is output to the image dividing unit 30.

  In the case of the present embodiment, the microcomputer 4 operates in the same manner as in the case of the first embodiment in the case of the first operation mode.

  On the other hand, in the second operation mode, the microcomputer 4 controls the operation of the gamma processing unit 40, the image synthesis unit 50, and the two-dimensional low-pass filter 60 based on the data related to the statistical distribution detected by the histogram detection unit 1. I do.

  Hereinafter, each component that functions in the second operation mode will be described in detail.

  The image dividing unit 30 divides an image to be displayed into a plurality of parts based on one image signal input via the selection unit 7.

  In the case of the present embodiment, specifically, the image dividing unit 30 divides the image into two parts, for example, a first divided image G1 and a second divided image G2.

  In the case of the present embodiment, for example, the mutual boundary line K between the first and second divided images G1 and G2 is set in advance, and the image dividing unit 30 originally uses the preset boundary line K as a boundary. One image is configured to be divided into first and second divided images. For example, the boundary line K is rectangular as shown in FIG.

  Here, for example, clock display in a television image is often performed at substantially the same position (display area) regardless of the selected channel.

  Therefore, in the case of the present embodiment, specifically, the image dividing unit 30 is, for example, an image of a display region (for example, the upper right portion of the screen) that is likely to be displayed on the display screen 21 of the display unit 20. Assume that the image is divided into (first divided image G1) and an image of the other display area (second divided image G2).

  Then, the image dividing unit 30 outputs an image signal corresponding to one of the divided images (first divided image G1) to the first gamma processing unit 41 (described later) and the histogram detecting unit 1 respectively.

  Further, the image dividing unit 30 outputs an image signal corresponding to the other divided image (second divided image G2) to a second gamma processing unit 42 (described later).

  In addition, the image dividing unit 30 outputs to the two-dimensional low-pass filter 60 an image signal corresponding to an image at the boundary between the two divided images (boundary image G3).

  Here, the boundary portion image G3 is an image having a predetermined area including the boundary line K between the first divided image G1 and the second divided image G2. For example, as shown by hatching in FIG. It is an image of a region sandwiched between two rectangles having the same center.

  The gamma processing unit 40 includes a first gamma processing unit 41 that performs gamma processing on an image signal corresponding to the first divided image G1, and a second gamma processing that performs image processing corresponding to the second divided image G2. A gamma processing unit 42.

  The first gamma processing unit 41 and the second gamma processing unit 42 individually select a gamma curve under the control of the microcomputer 4 and perform gamma processing on the image signal.

  That is, for example, as will be described later, if it is determined that there is a possibility that screen burn-in may occur in the display area of the first divided image G1 based on the detection result by the histogram detection unit 1, the microcomputer 4 A control signal is output to the first gamma processing unit 41 and the second gamma processing unit 42 to select a gamma curve that hardly causes screen burn-in.

  The first gamma processing unit 41 and the second gamma processing unit 42 select one optimal gamma curve from among a plurality of types of gamma curves set in advance as selection candidates, Apply gamma processing.

  The first and second gamma processing units 41 and 42 output image signals subjected to gamma processing to the image synthesis unit 50, respectively.

  In addition, the two-dimensional low-pass filter 60 applies to the image of the display area (range) designated by the microcomputer 4 in the boundary image between the first divided image G1 and the second divided image G2, that is, the boundary image G3. Then, a process for smoothing the image (smoothing process) is performed so that the image is blurred to make it less noticeable.

  That is, the two-dimensional low-pass filter 60 changes the display position from the portion close to the first divided image G1 to the second divided image G2 in each pixel included in the image of the display area specified by the microcomputer 4 in the boundary image G3. The display color and the display brightness are gradually changed over the close portion, and the image is dulled.

  More specifically, for example, when the display in the first divided image G1 is whitish and high brightness (due to a clock display or the like) and the display in the second divided image G2 is dark and low brightness, the second divided image The two-dimensional low-pass filter 60 performs filter processing so that the image is gradually changed to a brighter and brighter image as it approaches the first divided image G1 side from the G2 side.

  The two-dimensional low-pass filter 60 outputs the image signal after such smoothing processing to the image synthesis unit 50.

  The image combining unit 50 combines the image signals output from the first gamma processing unit 41, the second gamma processing unit 42, and the two-dimensional low-pass filter 60 into one image signal.

  Here, the first divided image G1 includes a portion that overlaps the boundary image G3 (a portion that overlaps the entire boundary image G3). Similarly, the second divided image G2 also includes a portion that overlaps each other. (This also overlaps the entire boundary image G3).

  Therefore, the image synthesizing unit 50 outputs the image signals output from the first and second gamma processing units 41 and 42 based on the image signal (boundary image G3) output from the two-dimensional low-pass filter 60 for these overlapping portions. (First divided image G1 and second divided image G2) are overwritten. That is, each overlapping portion in the first divided image G1 and the second divided image G2 is replaced with the boundary image G3.

  Here, the microcomputer 4 determines whether or not the smoothing processing result by the two-dimensional low-pass filter 60 is reflected on the image according to the detection result by the histogram detection unit 1 and reflects the smoothing processing result on the image. A command signal as to whether or not to perform the operation is output to the image composition unit 50.

  That is, for example, if the microcomputer 4 determines that there is no possibility of image burn-in based on the detection result by the histogram detection unit 1, the microcomputer 4 does not reflect the smoothing processing result by the two-dimensional low-pass filter 60 on the image. The command signal is output to the image composition unit 50. In this case, the image synthesizing unit 50 does not synthesize the image signal output from the two-dimensional low-pass filter 60 (the boundary image G3), and does not synthesize the image signal output from the first and second gamma processing units 41 and 42 (first Only the one divided image G1 and the second divided image G2) are synthesized.

  On the other hand, if it is determined that there is a possibility that screen burn-in may occur based on the detection result by the histogram detection unit 1, the microcomputer 4 instructs the image to reflect the smoothing processing result by the two-dimensional low-pass filter 60. The signal is output to the image composition unit 50. In this case, the image synthesis unit 50 synthesizes the three image signals output from the first gamma processing unit 41, the second gamma processing unit 42, and the two-dimensional low-pass filter 60 into one image signal.

  Next, in the second operation mode in the case of the present embodiment, for example, the histogram detection unit 1 has, for example, a statistical distribution for each luminance level of pixels included in the first divided image G1 (hereinafter, luminance level). Distribution).

  The detection operation by the histogram detection unit 1 is the same as that in each of the above embodiments.

  The histogram detection unit 1 outputs the luminance level distribution data (luminance level distribution data) thus detected to the microcomputer 4.

  The microcomputer 4 determines whether or not there is a possibility of screen burn-in in the display area of the first divided image G1 according to the luminance level distribution data from the histogram detection unit 1.

  In this embodiment, the determination operation by the microcomputer 4 is the same as the determination operation by the microcomputer 4 in each of the above embodiments.

  Further, in the second operation mode in the case of the present embodiment, when the microcomputer 4 determines that there is a possibility of screen burn-in by such a determination operation, the microcomputer 4 reduces the occurrence of burn-in. Control data is output to the 1 gamma processing unit 41, the second gamma processing unit 42, the two-dimensional low-pass filter 60, and the image synthesis unit 50, respectively.

  That is, when the microcomputer 4 determines that there is a possibility that the image burn-in occurs, the first gamma processing unit generates a gamma curve that reduces the difference in brightness of each pixel in the image so as to reduce the occurrence of image burn-in. 41 is selected. That is, the gamma curve used for the gamma processing is changed from the previously selected gamma curve (for example, a standard gamma curve) to another gamma curve.

  Note that, for example, a standard gamma curve may be selected for the second gamma processing unit 42, or the brightness of the second divided image G2 is set to the brightness of the first divided image G1. You may make it select the gamma curve which approaches. That is, the difference in luminance level distribution between the second divided image G2 and the first divided image G1 may be reduced.

  Further, the microcomputer 4 outputs to the two-dimensional low-pass filter 60 a signal that designates a range to be subjected to the smoothing process in the boundary image G3. Here, for example, when it is determined that the first divided image G1 is extremely bright based on the detection result by the histogram detection unit 1, the range to be subjected to the smoothing process in the boundary image G3 is expanded. In the case where it is determined that the first divided image G1 is relatively dark, while the signal for instructing the output is output but the screen burn-in is highly likely to occur, the boundary image G3 is smoothed. A signal for instructing to reduce the range to be processed is output.

  Further, the microcomputer 4 instructs the image composition unit 50 to reflect the smoothing processing result by the two-dimensional low-pass filter 60 on the image.

  Therefore, when there is a possibility that the image burns in, the image burn-in in the display area of the first divided image G1 is reduced, and the boundary portion (boundary between the first divided image G1 and the second divided image G2) An image obtained by smoothing the partial image G3) is displayed on the display screen 21.

  On the other hand, if it is determined by the above determination that there is no possibility of image burn-in, the microcomputer 4 uses the standard gamma curve for both the first and second gamma processing units 41 and 42. In addition to processing, a command signal is output to the image synthesis unit 50 so that the result of smoothing processing by the two-dimensional low-pass filter 60 is not reflected in the image.

  Therefore, when there is no possibility of image sticking, both the first and second divided images G1 and G2 are displayed after being subjected to gamma processing using a standard gamma curve and smoothed by the two-dimensional low-pass filter 60. Only the first and second divided images G1 and G2 are combined and displayed without combining the boundary image G3.

  According to the sixth embodiment as described above, the burn-in reduction unit 10 is input in the case of the switching unit 7 that switches between the first operation mode and the second operation mode and the second operation mode. An image dividing unit 30 that divides an image to be displayed by one image signal into two, and in the second operation mode, image synthesis that combines the two images divided by the image dividing unit 30 into one And the gamma processing unit 40 that individually performs gamma processing on each of the two images after being divided by the image dividing unit 30 and before being combined by the image combining unit 50 in the case of the second operation mode. Therefore, in the second operation mode, a part of the image (first divided image G1) to be displayed by the one input image signal is an image in which the screen is likely to be burned. If there is, While performs gamma processing so as to reduce the difference in brightness in the image, gamma processing such that normal brightness in the other portion (second image G2) of the images may be subjected. Therefore, for example, the occurrence of burn-in on the display screen can be suitably reduced.

  Note that, in the first operation mode, the same function as the first embodiment is achieved, so that the same effect as the first embodiment is obtained.

  Here, although high-brightness image display involves high power consumption, if the image is likely to cause screen burn-in as described above, gamma processing is performed to reduce the difference in brightness in the image. As a result, the luminance of the display image can be reduced and the power consumption can be reduced.

  In addition, the histogram detection unit 1 of the burn-in reduction unit 10 performs, for one image (first divided image G1) among the images divided by the image dividing unit 30, statistics for each luminance level of pixels included in the image. The distribution is detected, and the gamma processing unit 40 performs gamma processing on the image according to the statistical distribution detected by the histogram detection unit 1, so that the optimum gamma processing is performed on each of the divided images. Can be done automatically.

  More specifically, the histogram detection unit 1 detects a statistical distribution of the number of pixels for each luminance level, and the microcomputer 4 determines whether or not there is a possibility of image burn-in based on the detected statistical distribution, Since the gamma processing unit 40 performs gamma processing on the image according to the determination result, it is possible to automatically perform optimal gamma processing on each of the divided images.

  Further, the burn-in reduction unit 10 includes a two-dimensional low-pass filter 60 that performs a process of smoothing a boundary image (boundary image G3) between a plurality of images divided by the image dividing unit. The image G3 can be smoothed. Therefore, since the boundary image G3 can be prevented from becoming obvious and the first divided image G1 and the second divided image G2 can be smoothly connected, the screen burn-in in the display area of the boundary image G3 can be prevented. Generation | occurrence | production can be reduced suitably.

  Further, by enlarging or reducing the range of the image subjected to the smoothing process in the boundary image G3, the smoothing process can be performed on an image in an appropriate range. For example, the smoothing process However, it is possible to prevent the image quality from being deteriorated because the range is too wide, and the boundary line of the image from remaining apparent because the range of the smoothing process is too narrow.

  Further, since it is possible to control whether or not the result of the smoothing process is reflected on the display image, the result of the smoothing process can be reflected on the display image only when the smoothing process is necessary. .

  In the sixth embodiment, the example in which the structure of the first embodiment is partially changed has been described. However, the same change is applied to any of the second to fifth embodiments. However, the same applies.

  In the sixth embodiment, the example in which the gamma processing unit 40 individually performs optimum gamma processing on each of the images divided by the image dividing unit 30 has been described. The gamma processing unit 40 may perform optimal gamma processing on at least one of the images divided by the above. That is, for example, in the case where standard gamma processing has already been performed on the original image signal input to the burn-in reduction unit 10, the gamma processing unit 40, for example, Individual gamma processing may be performed only on the divided image G1 to reduce screen burn-in.

  In the sixth embodiment, the example in which the first divided image G1 is set in the upper right area of the display screen 21 has been described. However, the setting of the area of the first divided image G1 can be arbitrarily changed according to the purpose. You may do it. That is, in the case of the first embodiment, the first divided image G1 is set in the upper right area of the display screen 21 in order to detect the presence or absence of clock display or channel display. When detecting the presence or absence of the image, the first divided image G1 may be set in the lower area of the display screen 21. Moreover, although the example which set the boundary line K1 to the rectangular shape was demonstrated, you may change arbitrarily the shape of this boundary line K1 according to the objective.

  Furthermore, in the above sixth embodiment, when it is determined that image sticking occurs, when the image composition unit 50 configures each image, the first divided image G1 and the second divided image G2 are respectively converted into the third divided image. Although an example of overwriting with G3 has been described, for the overlapping portion of the first divided image G1 and the third divided image G3, an image obtained by averaging both the images G1, G3 is displayed, and similarly, the second divided image G2 is displayed. For the overlapping portion between the first divided image G3 and the third divided image G3, an image obtained by averaging both the images G2 and G3 may be displayed.

  Alternatively, in the sixth embodiment, the example in which the first divided image G1 and the second divided image G2 each have a portion that overlaps the boundary image G3 has been described, but the overlapping portion does not exist. It is also preferable to divide the first divided image G1, the second divided image G2, and the boundary portion image G3. That is, for example, as shown in FIG. 20, among the two rectangular boundary lines K1 and K2 that are similar to each other and have the same center, the first divided image G1 and the boundary image G3 are separated by the inner boundary line K1. On the other hand, the second divided image G2 and the boundary image G3 may be divided by the outer boundary line K2, and the image of the region sandwiched by these boundary lines K1 and K2 may be used as the boundary image G3.

  In the sixth embodiment, the example in which the range to be smoothed in the boundary image G3 is enlarged or reduced according to the detection result by the histogram detection unit 1 has been described. The range to be subjected to the conversion process may be constant (for example, the entire boundary image G3 is always).

  In the sixth embodiment, the image synthesis unit 50 is instructed to reflect the result of the smoothing process by the two-dimensional low-pass filter 60 on the image, so that the image of the smoothing process result is displayed. In the above example, the presence / absence of the reflection is controlled. However, instead of the instruction to the image composition unit 50, the instruction to the two-dimensional low-pass filter 60 is given to control whether the smoothing processing result is reflected on the image. Anyway. That is, when the detection result by the histogram detection unit 1 is a detection result that may cause screen burn-in in the display area of the first divided image G1, the microcomputer 4 applies the two-dimensional low-pass filter 60 to the two-dimensional low-pass filter 60. If the detection result is such that there is no possibility of image sticking in the display area of the first divided image G1 while the control signal is output and the boundary image G3 is smoothed. The control signal may be output from the microcomputer 4 to the two-dimensional low-pass filter 60 so that the process of smoothing the boundary image G3 is not performed.

[Seventh Embodiment]
FIG. 21 is a block diagram illustrating a configuration of a display device 700 according to the seventh embodiment.

  In the sixth embodiment, the example in which the histogram detection unit 1 detects the statistical distribution for each luminance level of the pixels included in the image only for the first divided image G1 in the second operation mode has been described. However, in the seventh embodiment, an example will be described in which the histogram detection unit 70 individually detects the luminance level distribution for each of the first and second divided images G1 and G2 in the second operation mode.

  The display device 700 according to the seventh embodiment is different from the display device 600 according to the sixth embodiment only in the points described below, and the display device 600 according to the sixth embodiment is otherwise different. Therefore, in the display device 700 according to the seventh embodiment, the same components as those of the display device 600 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 21, in the present embodiment, a histogram detection unit 70 is provided instead of the histogram detection unit 1. The histogram detection unit 70 includes a first histogram detection unit 71 and a second histogram detection unit 72.

  Among these, the 1st histogram detection part 71 functions similarly to the histogram detection part 1 in the case of said each embodiment in the 1st operation mode.

  In the present embodiment, the switching unit 7 outputs the input image signal to the first histogram detection unit 71 when the operation mode is switched to the first operation mode, while the operation mode is set to the second operation mode. When switching to the operation mode, the input image signal is output to the image dividing unit 30.

  In the second operation mode in the present embodiment, the image dividing unit 30 outputs an image signal corresponding to the first divided image G1 to the first histogram detecting unit 71, while the second dividing mode. An image signal corresponding to the image G2 is output to the second histogram detector 72.

  The first histogram detector 71 detects the luminance level distribution for the first divided image G1, while the second histogram detector 72 detects the luminance level distribution for the second divided image G2.

  In the second operation mode in the present embodiment, the microcomputer 4 performs, for example, the control described below.

  First, for the first and second divided images G1 and G2, the microcomputer 4 determines, for example, whether there is a possibility of image burn-in and whether the image is not too dark.

  That is, based on the detection data from the first histogram detection unit 72, the microcomputer 4 determines whether there is a possibility of screen burn-in in the first divided image G1 as described in the sixth embodiment. In addition to the determination, whether or not the first divided image G1 is too dark is determined based on the detection data.

  Similarly, the microcomputer 4 determines whether or not there is a possibility of image burn-in in the second divided image G2 based on the detection data from the second histogram detection unit 72, and the second divided image G2 is dark. Judge whether it is too much.

  Furthermore, the microcomputer 4 determines whether or not the difference in brightness between the first divided image G1 and the second divided image G2 is too large.

  If the microcomputer 4 determines that there is a possibility of screen burn-in in the first divided image G1, the microcomputer 4 outputs control data to the first gamma processing unit 41, and the brightness of each pixel in the first divided image G1. By selecting a gamma curve that reduces the difference between the two, the occurrence of burn-in is reduced.

  Similarly, when it is determined that there is a possibility of screen burn-in in the second divided image G2, the microcomputer 4 outputs control data to the second gamma processing unit 42, and each pixel in the second divided image G2 is output. By selecting a gamma curve that reduces the difference between light and dark, the occurrence of burn-in is reduced.

  If it is determined that the first divided image G1 is too dark, the microcomputer 4 outputs control data to the first gamma processing unit 41, and increases the number of gradations in the first divided image G1. To improve the image quality of the first divided image G1.

  Similarly, when it is determined that the second divided image G2 is too dark, the microcomputer 4 outputs control data to the second gamma processing unit 42, and increases the number of gradations in the second divided image G2. The curve is selected to improve the image quality of the second divided image G2.

  If it is determined that the difference in brightness between the first divided image G1 and the second divided image G2 is too large, the microcomputer 4 reduces the difference in brightness between the two images G1 and G2. Control data is output to the second gamma processing units 41 and 42, respectively, and gamma curves that reduce the difference in brightness between the first divided image G1 and the second divided image G2 are selected, and the display screen 21 is selected. Improve the overall image quality.

  If the microcomputer 4 determines that there is a possibility of screen burn-in in any one of the first and second divided images G1 and G2, any of the first and second divided images G1 and G2 will be described. When it is determined that one of them is too dark, or when it is determined that the difference in brightness between the first and second divided images G1 and G2 is too large, the result of smoothing processing by the two-dimensional low-pass filter 60 is reflected in the image. The image composition unit 50 is instructed to do so.

  Here, for example, when the microcomputer 4 determines that the difference in brightness between the first divided image G1 and the second divided image is large based on the detection result by the histogram detection unit 70, the microcomputer 4 includes the boundary image G3. A signal for instructing to enlarge the range to be smoothed is output to the two-dimensional low-pass filter 60. On the other hand, there is a possibility of screen burn-in in either one of the first and second divided images G1 and G2, or either one of the first and second divided images G1 and G2 is too dark. Even in this case, if it is determined that the difference in brightness between the first divided image G1 and the second divided image is small, a command is given to reduce the range to be smoothed in the boundary image G3. Is output to the two-dimensional low-pass filter 60.

  According to the seventh embodiment as described above, the following effects are obtained in addition to the same effects as in the case of the sixth embodiment.

  In the second operation mode, the first divided image G1 and the second divided image G2 are individually determined (for example, whether there is a possibility of image burn-in, whether the image is not too dark, the image Since the gamma processing is separately performed on the first divided image G1 and the second divided image G2 according to the determination result, the sixth view is performed. The gamma processing can be performed on each of the images G1 and G2 more preferably than in the embodiment.

  That is, for example, with respect to the display areas of the first and second divided images G1 and G2, the occurrence of image burn-in is individually reduced, the image quality of dark images is individually improved, or the first and second divided images are divided. It is possible to improve the image quality of the entire display screen 21 by reducing the difference in image quality between the display areas of the images G1 and G2 (determined based on the difference in luminance level distribution).

  In the seventh embodiment, the example in which the image dividing unit 30 divides the image into two parts has been described. However, the image may be divided into three or more parts. In this case, assuming that the number of image divisions is n (= 3 or more), the gamma processing unit 40 includes, for example, at least (n−1) or n gamma processing units, and the histogram detection unit 70 also includes: At least (n-1) or n histogram detection units are provided, and at least (n-1) or n images out of n divided images are individually provided. It is preferable to detect the luminance level distribution and individually perform gamma processing according to the detected luminance level distribution.

[Eighth Embodiment]
FIG. 22 is a block diagram showing a configuration of a display device 800 according to the eighth embodiment.

  In the sixth and seventh embodiments, the example in which the image dividing boundary by the image dividing unit 30 is set in advance has been described. However, in the eighth embodiment, the luminance level distribution detected by the histogram detecting unit 1 is described. An example of determining an image division boundary based on the above will be described.

  The display device 800 according to the eighth embodiment is different from the display device 600 according to the sixth embodiment only in the points described below, and the display device 600 according to the sixth embodiment is otherwise different. Therefore, in the display device 800 according to the eighth embodiment, the same components as those of the display device 600 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 22, in the present embodiment, the histogram detection unit 1 is provided, for example, before the image dividing unit 30 and the switching unit 7.

  In the second operation mode, an image signal is input to the image dividing unit 30 via the histogram detection unit 1 and the switching unit 7.

  On the other hand, in the first operation mode, an image signal is input to the luminance correction unit 2 via the histogram detection unit 1 and the switching unit 7.

  The gamma processing unit 40 includes, for example, first to fourth gamma processing units 41, 42, 43, and 44.

  In the second operation mode in the present embodiment, the histogram detection unit 1 is configured to be able to perform the following two types of detection operations, for example.

  (1-1) An operation of detecting a luminance level distribution for each of the images (first and second divided images G11 and G12 in FIG. 23A) displayed in each display area obtained by dividing the display screen 21 into two.

  (1-2) An operation of detecting the luminance level distribution for each of the images (first to fourth divided images G11 to G14 in FIG. 23B) displayed in each display area obtained by dividing the display screen 21 into four.

  The microcomputer 4 performs the following determination operation, and controls the gamma control unit 40, the two-dimensional low-pass filter 60, and the image composition unit 50 according to the determination result.

  (2-1) Based on the result of the detection operation (1-1) by the histogram detection unit 1, only one of the first divided image G11 and the second divided image G12 in FIG. When it is determined that there is a problem that the screen is too dark or there is a possibility of image burn-in, or when it is determined that there is a problem that the contrast between the images G11 and G12 is too large, these first and second divided images It is determined that G11 and G12 should be divided. That is, in this case, it is determined that the image on the display screen 21 should be divided into two in the form shown in FIG.

  Further, in this case, the image dividing unit 30 divides the image on the display screen 21 into the first divided image G11 and the second divided image G12 in FIG. 23A, and images corresponding to the divided images. A command to output a signal to the first and second gamma processing units 41 and 42 and a boundary image between the first and second divided images G11 and G12 (for example, in FIG. And a command to output to the two-dimensional low-pass filter 60 an image in the vicinity of a straight boundary line as shown in FIG.

  The two-dimensional low-pass filter 60 is instructed to enlarge or reduce the smoothing processing range according to the type and degree of problem in the images G11 and G12.

  The image composition unit 50 is instructed to synthesize the images G11 and G12 and their boundary images.

  (2-2) When it is determined that the first and second divided images G11 and G12 should not be divided based on the result of the detection operation (1-1) by the histogram detection unit 1, the histogram detection unit 1 Based on the result of the detection operation of (1-2) above, it is determined that only one of the first to fourth divided images G11 to G14 is too dark or there is a possibility of screen burn-in. If it is determined that there is a problem that only one of the images has a too large difference in contrast with the other images, the one image (FIG. 23 (b) )), It is determined that only one of the first to fourth divided images G11 to G14) should be divided. That is, in this case, it is determined that the image on the display screen 21 should be divided into two in the manner shown in FIG.

  In this case, the image dividing unit 30 has any one of the problematic images (any one of the first to fourth divided images G11 to G14) out of the entire display screen 21. Only split. That is, in this case, an image signal corresponding to one problematic image (for example, the first divided image G11) among the first to fourth divided images G11 to G14 is output to the first gamma processing unit 41. On the other hand, an instruction to output image signals corresponding to the remaining three images (for example, the second to fourth divided images G12 to G14) to the second gamma processing unit 42, and the problem 1 A command to output the boundary image between one image and the other three images to the two-dimensional low-pass filter 60 is issued to the image dividing unit 30.

  The two-dimensional low-pass filter 60 is instructed to expand or reduce the smoothing processing range in accordance with the type and degree of problem in the problematic image.

  For the image composition unit 50, the one problematic image, the other three images, and their boundary image (for example, an L-shaped boundary line as shown in FIG. 23C) And an image in the vicinity of).

  (2-3) When it is determined that the first and second divided images G11 and G12 should not be divided based on the result of the detection operation (1-1) by the histogram detection unit 1, the histogram detection unit 1 Based on the result of the detection operation of (1-2) above, any one of the first to fourth divided images G11 to G14 that is not adjacent to each other (a combination of the image G11 and the image G14, or When it is determined that the combination of the image G11 and the image G14) has at least one of the following three problems: too dark, possible screen burn-in, and too large contrast between adjacent images Determines that the first to fourth divided images G11 to G14 should be divided from each other. That is, in this case, it is determined that the image on the display screen 21 should be divided into four in the manner shown in FIG.

  In this case, the image dividing unit 30 divides the image on the display screen 21 into first to fourth divided images G11 to G14 shown in FIG. 23B, and image signals corresponding to the divided images. Is output to the first to fourth gamma processing units 41 to 44 and the boundary image between the first to fourth divided images G11 to G14 (for example, as shown in FIG. 23B). And an instruction to output to the two-dimensional low-pass filter 60.

  The two-dimensional low-pass filter 60 is instructed to enlarge or reduce the smoothing processing range according to the type and degree of the problem in the two problematic images.

  Here, the boundary portion image includes a portion that is a boundary portion between the first divided image G11 and the second divided image G12, a portion that is a boundary portion between the first divided image G11 and the third divided image G13, and a first portion. There are four parts: a part that is a boundary part between the two-divided image G12 and the fourth divided image G14, and a part that is a boundary part between the third divided image G13 and the fourth divided image G14. Therefore, for the two-dimensional low-pass filter 60, the range of the smoothing process may be individually commanded for each of these four portions.

  The image synthesis unit 50 is instructed to synthesize the first divided image G11, the second divided image G12, the third divided image G13, the fourth divided image G14, and their boundary image. .

  (2-4) When the histogram detection unit 1 determines that the first and second divided images G11 and G12 should not be divided based on the detection operation result of (1-1) above, the histogram detection unit 1 Based on the detection result of (1-2) above, only two images (for example, the first and third divided images G11 and G13) adjacent to each other among the first to fourth divided images G11 to G14 are included. There is at least one of the three problems: too dark, possible screen burn-in, too large contrast between adjacent images, and two adjacent images (e.g., When it is determined that the types of problems in the first and third divided images G11 and G13) are different from each other (for example, one is too dark and the other may be burned), the image of the entire display screen 21 is displayed. Only two adjacent images (for example, the first and third divided images G11 and G13) are divided independently of each other, while the remaining two images (for example, the second and fourth divided images G12) are divided. , G14) determine that it should be left undivided. That is, in this case, it is determined that the image on the display screen 21 should be divided into three in the manner shown in FIG.

  Further, in this case, only two images (for example, the first and third divided images G11 and G13) that are problematic and adjacent to each other are selected from the images of the entire display screen 21 with respect to the image dividing unit 30. Each of the images is divided independently, and the remaining two images are left in a grouped state. That is, in this case, an image signal corresponding to one of the two images that are problematic and adjacent to each other (for example, the first divided image G1) is output to the first gamma processing unit 41, and the other (for example, the first image) The image signals corresponding to the three divided images G13) are output to the second gamma processing unit 42, and the image signals corresponding to the remaining two (for example, the second and fourth divided images G12 and G14) are collectively third. A boundary image between the instruction to output to the gamma processing unit 43, the two problematic images, and the remaining two images (for example, as shown in FIG. 23D) The image dividing unit 30 is instructed to output the image in the vicinity of the T-shaped boundary line) to the two-dimensional low-pass filter 60.

  The two-dimensional low-pass filter 60 is instructed to enlarge or reduce the smoothing processing range according to the type and degree of the problem in the two problematic images.

  Here, the boundary image includes a portion that is a boundary between the first divided image G11 and the second divided image G12, and, for example, in the case of the example of FIG. It is a boundary part between the third divided image G13, a part that is a boundary part between the first divided image G11 and the second divided image G12, and a boundary part between the third divided image G13 and the fourth divided image G14. There are three parts. Therefore, for the two-dimensional low-pass filter 60, the range of the smoothing process may be individually commanded for each of these three portions.

  For the image composition unit 50, each divided image, that is, for example, an image composed of the first divided image G11, the third divided image G13, the second and fourth divided images G12, G14, and their images. A command is made to synthesize the boundary image.

  (2-5) If the determination does not correspond to any of the above (2-1) to (2-4), it is determined that the first to fourth divided images G11 to G14 should not be divided.

  In this case, the image dividing unit 30 is instructed to output only the image signal corresponding to the entire image, for example, only to the first gamma processing unit 41 without dividing the image on the display screen 21.

  In addition, the image dividing unit 30 divides the image displayed on the display screen 21 in, for example, the following four types in accordance with a command from the microcomputer 4.

  (3-1) When the determination of (2-1) is made by the microcomputer 4, the image on the display screen 21 is divided into the first divided image G11 and the second divided image G12 in FIG. The image signal corresponding to one of the divided images is output to the first gamma processing unit 41, and the image signal corresponding to the other is output to the second gamma processing unit 42, and the boundary image between the images is displayed. The corresponding image signal is output to the two-dimensional low-pass filter 60.

  (3-2) If the determination of (2-2) is made by the microcomputer 4, any one of the problematic images (the first one in FIG. 23B) is selected from the images on the entire display screen 21. (Any one of the fourth divided images G11 to G14) is divided, and the image signal corresponding to the divided one image corresponds to the remaining three images in the first gamma processing unit 41. The image signal is output to the second gamma processing unit 42, and a boundary image between one problematic image and the other three images is output to the two-dimensional low-pass filter 60.

  (3-3) When the determination of (2-3) is made by the microcomputer 4, the image on the display screen 21 is divided into four first to fourth divided images G11 to G14 in FIG. Of the divided images, the image signal corresponding to the first divided image G11 corresponds to the first gamma processing unit 41, the image signal corresponding to the second divided image G12 corresponds to the second gamma processing unit 42, and the third divided image G13. The image signal to be output is output to the third gamma processing unit 43 and the image signal corresponding to the fourth divided image G14 is output to the fourth gamma processing unit 44, respectively, and between the first to fourth divided images G11 to G14. The boundary image is output to the two-dimensional low-pass filter 60.

  (3-4) When the determination of (2-4) is made by the microcomputer 4, only the two images that are problematic and adjacent to each other are divided independently from each other on the entire display screen 21. The remaining two images are left in a grouped state. That is, an image signal corresponding to one of the two images that are problematic and adjacent to each other (for example, the first divided image G1 in FIG. 23D) is output to the first gamma processing unit 41, and the other An image signal corresponding to (for example, the third divided image G13 in FIG. 23D) is output to the second gamma processing unit 42, and the remaining two (for example, the second and fourth divisions in FIG. 23D). Image signals corresponding to the images G12 and G14) are collectively output to the third gamma processing unit 43, and a boundary image between the two problematic images and the remaining two images. Is output to the two-dimensional low-pass filter 60.

  (3-5) When the determination of (2-5) is made by the microcomputer 4, an image signal corresponding to the image of the entire display screen 21 is output only for gamma processing.

  Each of the gamma processing units 41 to 44 performs gamma processing on the image signal input from the image dividing unit 30 using a gamma curve selected in accordance with a command from the microcomputer 4, and the processed image signal Is output to the image composition unit 50.

  When the image is not divided, no image signal is input to the second to fourth gamma processing units 42 to 44, and these second to fourth gamma processing units 42 to 44 do not perform gamma processing and the image. No image signal is output to the combining unit 50.

  When the image is divided into two, no image signal is input to the third and fourth gamma processing units 43 and 44, and the third and fourth gamma processing units 43 and 44 do not perform gamma processing. At the same time, no image signal is output to the image composition unit 50.

  Further, when the image is divided into three, no image signal is input to the fourth gamma processing unit 44, and the fourth gamma processing unit 44 does not perform gamma processing and outputs an image signal to the image composition unit 50. Is not output.

  The two-dimensional low-pass filter 60 performs a smoothing process on the boundary image (for example, the image at the boundary of the image in any one of FIGS. 23A to 23D) input from the image dividing unit 30. Output to the image composition unit 50.

  When the image is not divided, the image signal is not input to the two-dimensional low-pass filter 60, and the two-dimensional low-pass filter 60 does not perform the smoothing process and does not output the image signal to the image synthesis unit 50.

  In addition, when the image is divided into two, the image synthesis unit 50 synthesizes each image signal input from the first gamma processing unit 41, the second gamma processing unit 42, and the two-dimensional low-pass filter 60, and displays the display unit. 20, and when the image is divided into three, each image signal input from the first gamma processing unit 41, the second gamma processing unit 42, the third gamma processing unit 43, and the two-dimensional low-pass filter 60. Are combined and output to the display unit 20, and when the image is divided into four, the first gamma processing unit 41, the second gamma processing unit 42, the third gamma processing unit 43, and the fourth gamma processing unit 44 are combined. The image signals input from the two-dimensional low-pass filter 60 are combined and output to the display unit 20. When the image is not divided, the image composition unit 50 outputs the image signal of the entire display screen 21 input from the first gamma processing unit 41 to the display unit 20 as it is, for example.

  Next, the operation in the second operation mode in this embodiment will be described.

  First, the microcomputer 4 outputs a command to the histogram detection unit 1 to detect the luminance level distribution for each of the first divided image G11 and the second divided image G12 in FIG.

  Then, the histogram detection unit 1 detects the luminance level distribution for each of the first divided image G11 and the second divided image G12 in FIG. 23A, and outputs data of the detection result to the microcomputer 4.

  The microcomputer 4 determines whether or not the image on the display screen 21 should be divided into the first divided image G11 and the second divided image G12 in FIG. 23A based on the data of these two luminance level distributions. .

  Here, for example, when only one of the first divided image G11 and the second divided image G12 in FIG. 23A is too dark, the microcomputer 4 may cause screen burn-in to only one of them. If there is a difference, or if the difference in brightness between the images G11 and G12 is too large, it is determined that the first and second divided images G11 and G12 should be divided.

  When the microcomputer 4 determines that the first and second divided images G11 and G12 in FIG. 23A should be divided, the microcomputer 4 instructs the image dividing unit 30 to do so.

  The image dividing unit 30 divides the image into the first and second divided images G11 and G12 in FIG. 23A according to this instruction, and the image signal corresponding to the first divided image G11 is the first gamma processing unit 41. The image signal corresponding to the second divided image G12 is sent to the second gamma processing unit 42, and the image signal corresponding to the boundary image between the first and second divided images G11 and G12 is sent to the two-dimensional low-pass filter 60. , Respectively.

  In addition, the microcomputer 4 instructs the first and second gamma processing units 41 and 42 in the same manner as described in the second embodiment, respectively, to select the optimum gamma curve, respectively, and burn-in. Reduce occurrence or improve image quality.

  Further, the microcomputer 4 gives the same command as described in the second embodiment to the two-dimensional low-pass filter 60 to enlarge or reduce the range to be subjected to the smoothing process.

  In addition, the microcomputer 4 instructs the image composition unit 50 to reflect the smoothing processing result by the two-dimensional low-pass filter 60 on the image.

  On the other hand, if it is determined that the first and second divided images G11 and G12 in FIG. 23A should not be divided, the microcomputer 4 outputs a command to the histogram detection unit 1, and FIG. The luminance level distribution is detected for each of the first divided image G11, the second divided image G12, the third divided image G13, and the fourth divided image G14.

  Then, the histogram detection unit 1 detects the luminance level distribution for each of the first to fourth divided images G11 to G14 in FIG. 23B, and outputs the detection result data to the microcomputer 4.

  The microcomputer 4 determines whether or not the image on the display screen 21 should be divided into any of the first to fourth divided images G11 to G14 in FIG. 23B based on the data of these four luminance level distributions. I do.

  Here, the microcomputer 4 is, for example, when any of the first to fourth divided images G11 to G14 in FIG. 23B is too dark, or when there is a possibility that any of the images is burned on the screen, When the difference in brightness between any adjacent images is too large, it is determined that the image should be divided.

  That is, for example, only one of the first to fourth divided images G11 to G14 (for example, the first divided image G11) is too dark, and there is a possibility of screen burn-in, with other images. When there is a problem that the difference between light and dark is too large, it is determined that only one image (for example, the first divided image G11) should be divided from the entire image of the display screen 21 ((2 -2).

  Alternatively, for example, when only two of the first to fourth divided images G11 to G14 that are not adjacent to each other (for example, the first and fourth divided images G11 and G14) are too dark, If there is a possibility that only one image is burned in the screen, or if the difference in brightness between each of the two images is too large, the first to fourth divided images G11 to G14 are mutually connected. Is determined to be divided (determination (2-3) above).

  Or, for example, two adjacent images (for example, the first and third divided images G11 and G13) among the first to fourth divided images G11 to G14 are too dark, or the screen can be burned. Or when the contrast between the adjacent images is too large and the image quality of the two adjacent images (for example, the first and third divided images G11 and G13) are different from each other ( For example, in the case where one is too dark and the other is likely to be burned in), two adjacent images (for example, the first and third divided images G11, G13) is determined to be divided (determination (2-4) above).

  If the microcomputer 4 determines that the first to fourth divided images G11 to G14 in FIG. 23B should be divided, the microcomputer 4 gives an instruction on how to divide the image to the image dividing unit 30. The above is performed as described above.

  The image dividing unit 30 appropriately divides the image in accordance with this command, for example, as shown in FIG. 23B, FIG. 23C, or FIG. 23D, and corresponds to the first image among them. The image signal corresponding to the first gamma processing unit 41, the image signal corresponding to the second image to the second gamma processing unit 42, the image signal corresponding to the third image to the third gamma processing unit 43, 4 The image signal corresponding to the first image is output to the fourth gamma processing unit 44, and the image signal corresponding to the boundary image between the divided images is output to the two-dimensional low-pass filter 60. Note that the third and fourth images do not exist in the case of division in the manner as shown in FIG. 23C, and the fourth image in the case of division in the manner as shown in FIG. There is no image.

  The microcomputer 4 is described in the seventh embodiment with respect to any two to four processing units 41 to 44 to which an image signal is input from among the first to fourth gamma processing units 41 to 44. The same command as described above is performed to select the optimum gamma curve for each, thereby reducing the occurrence of burn-in and improving the image quality.

  Further, the microcomputer 4 gives the same command as described in the seventh embodiment to the two-dimensional low-pass filter 60 to enlarge or reduce the range to be subjected to the smoothing process.

  In addition, the microcomputer 4 instructs the image composition unit 50 to reflect the smoothing processing result by the two-dimensional low-pass filter 60 on the image.

  On the other hand, when it is determined that any of the first to fourth divided images G11 to G14 in FIG. 23B should not be divided (determination (2-5) above), the microcomputer 4 divides the image. The image dividing unit 30 is instructed not to perform the process. In this case, the image dividing unit 30 outputs an image signal corresponding to the image of the entire display screen 21 only to the first gamma processing unit 41, for example, and the first gamma processing unit 41 outputs the image signal to this image signal. A standard gamma process is applied uniformly and output to the image composition unit 50. Further, the image composition unit 50 outputs the image signal from the first gamma processing unit 41 to the display unit 20 as it is.

  Thereafter, similarly, the determination based on the luminance level distribution for the first and second divided images G11 and G12 in FIG. 23A and the first to fourth divided images G11 to G14 in FIG. The determination based on the luminance level distribution is repeatedly performed, and the image is divided and gamma processing is performed individually according to the determination result, or uniform gamma processing is performed without dividing the image.

  According to the eighth embodiment as described above, in addition to the effects obtained by the seventh embodiment, the following effects are obtained.

  That is, according to the eighth embodiment, the image division boundary is determined based on the luminance level distribution detected by the histogram detection unit 1 in the second operation mode. , And gamma processing can be applied to each of the divided images.

  In the eighth embodiment, an example in which an image can be divided up to four divisions has been described. However, the image may be divided into five or more.

  Specifically, for example, the number of image divisions and the boundary of the image are subdivided while sequentially subdividing the area of the image as the detection target of the luminance level distribution, such as 2 division → 4 division → 8 division →. It is also preferable to determine.

  In the above eighth embodiment, for example, when any one of the two divided images is too dark or there is a possibility of image burn-in, the number of divisions and the division boundary are immediately determined. However, if one of the two divided images is too dark or there is a possibility of screen burn-in on one of the images, the one image is further subdivided. Thus, it is also preferable to determine the optimum division boundary of the image. That is, for example, when one of the first and second divided images G11 and G12 in FIG. 23 (a) is too dark or there is a possibility of image burn-in, the one image (for example, the first image) The one-divided image G11) is divided into the first divided image 11 and the third divided image 13 in FIG. 23B, the luminance level distribution of each of the divided is determined, and only one of them is determined (for example, the first divided image G11) When the three-divided image G13) is dark, or when there is a possibility of image burn-in on only one of the images (for example, the third divided image G13), only the image (for example, the third divided image G13) is replaced with another portion. On the other hand, if the luminance level distribution of both images is not so different in the determination, the first and third divided images 11 and 13 in FIG. 23B are not divided, and FIG. First in Beauty second image G11, may be divided into G12.

<Modification>
FIG. 24 is a block diagram illustrating a configuration of a display device 850 according to a modification of the eighth embodiment.

  In the eighth embodiment, the example in which the histogram detection unit 1 is provided in the preceding stage of the image dividing unit 30 as illustrated in FIG. 22 has been described. However, for example, as illustrated in FIG. Through the image segmentation unit 30 (in the second operation mode) or the histogram detection unit 1 (in the first operation mode), alternatively, the image signal (the image corresponding to the entire display screen 21). Signal) may be input. In this case, the same effect as described above can be obtained.

[Ninth Embodiment]
In the sixth to eighth embodiments, the image dividing boundary by the image dividing unit 30 is set in advance, or based on the luminance level distribution detected by the histogram detecting unit (histogram detecting unit 1 or 70). In the ninth embodiment, an example in which an image division boundary is set by a user operation will be described.

  Further, in the sixth to eighth embodiments, the example in which the range for performing the smoothing process is automatically determined by the two-dimensional low-pass filter 60 has been described, but in the ninth embodiment, the smoothing process is performed. An example in which the range is also set by a user operation will be described.

  Furthermore, in the sixth to eighth embodiments, the example in which it is automatically determined whether or not the result of the smoothing process by the two-dimensional low-pass filter 60 is reflected has been described. In the ninth embodiment, however. An example in which whether or not to reflect the result of the smoothing process by the two-dimensional low-pass filter 60 is also set by a user operation will be described.

  FIG. 25 is a block diagram illustrating a configuration of a display device 900 according to the ninth embodiment.

  The display device 900 according to the ninth embodiment is different from the display device 700 according to the seventh embodiment only in the points described below, and the display device 700 according to the seventh embodiment is otherwise different. Therefore, in the display device 900 according to the ninth embodiment, the same components as those of the display device 700 are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 25, in the case of the present embodiment, the display device 900 includes an operation unit 90 operated by a user. The operation unit 90 includes, for example, a GUI (Graphical User Interface) such as a mouse and operation keys (operation buttons).

  When the operation unit 90 detects an operation by the user, the operation unit 90 outputs a detection signal corresponding to the type of operation to the microcomputer 4. The microcomputer 4 outputs a command signal to the image dividing unit 30, the two-dimensional low-pass filter, and the image synthesizing unit 50 in accordance with the type of detection signal input from the operation unit 90.

  In the case of the present embodiment, the image dividing unit 30 is configured to divide an image only in accordance with a command from the microcomputer 4, for example, and does not divide the image when there is no command from the microcomputer 4. In addition, an image signal corresponding to the entire image on the display screen 21 is output only to the first gamma processing unit 41.

  Therefore, when there is no instruction from the microcomputer 4 to the image dividing unit 30, only the first gamma processing unit 41 performs gamma processing and outputs an image signal to the image synthesis unit 50, and the second gamma processing unit 42 Gamma processing is not performed and the image signal is not output to the image composition unit 50.

  When there is no command from the microcomputer 4 to the image dividing unit 30, the histogram detecting unit 70 does not detect the luminance level distribution, the two-dimensional low-pass filter 60 does not perform the smoothing process, and the image synthesizing unit 50 The image signal input from the first gamma processing unit 41 is output to the display unit 20 without being synthesized.

  Next, the operation in this embodiment will be described.

  First, the user determines whether or not to divide the image in accordance with the image displayed on the display screen 21. In the case of dividing, the user operates the operation unit 80 to divide the image into two at a desired boundary line. To do.

  Here, the image is divided, for example, when clock display, channel display, movie subtitle display is performed, or when it is recognized that a signal of two screens exists in one screen (news etc., two relay locations, For example, one is a relay destination for reporting, and the other is when a studio or the like is projected together), or when an image with a large difference in contrast between a dark part and a bright part is displayed.

  When dividing an image, the operation unit 90 is operated to start dividing the image. Then, for example, a pointer P (see FIG. 25) or an indicator is displayed on the display screen 21.

  Then, for example, the user moves the pointer P to specify the range of the image to be divided. That is, for example, a rectangular frame W is displayed in the display screen 21 in accordance with the movement trajectory of the pointer P. When a drag operation or the like is performed so that the frame W has a desired position, size, and shape, Perform the image range determination operation.

  Here, the display of the pointer P and the frame W is performed, for example, by fitting and synthesizing by the image synthesis unit 50 under the control of the microcomputer 4 using the pattern data stored in the storage unit (not shown).

  Note that the frame W is not limited to a rectangular shape, and for example, an area closed by an arbitrary movement locus of the pointer P may be used as the frame W.

  Thus, when an operation for determining the image range using the operation unit 80 is performed, the microcomputer 4 outputs a command signal to the image dividing unit 30 so as to divide the image into two with the frame W as a boundary line.

  Upon receiving a command signal from the microcomputer 4, the image dividing unit 30 divides the image into two using the frame W as a boundary line, and outputs an image signal corresponding to one of the images (for example, the first divided image G1) to the first gamma. The image signal corresponding to the other image signal (for example, the second divided image G2) is output to the processing unit 41 to the second gamma processing unit 42, and the boundary between the first divided image G1 and the second divided image G2 is output. Part image (boundary part image G 3: not shown in FIG. 25) is output to the two-dimensional low-pass filter 60.

  Furthermore, the image dividing unit 30 outputs the divided images, that is, image signals corresponding to the first divided image G1 and the second divided image G2, to the first histogram detecting unit 71 and the second histogram detecting unit 72, respectively. To do.

  As described in the seventh embodiment, the microcomputer 4 performs the determination operation and controls the first gamma processing unit 41 and the second gamma processing unit 42 based on the determination result.

  Each of the first gamma processing unit 41 and the second gamma processing unit 42 selects a gamma curve according to a command from the microcomputer 4, performs gamma processing on the image signal using the selected gamma curve, and Output.

  On the other hand, the two-dimensional low-pass filter 60 performs a smoothing process on the image in the range determined by the previous setting operation by the user in the boundary image G3, and outputs it to the image composition unit 50.

  The image synthesis unit 50 synthesizes the first divided image G1 from the first gamma processing unit 41, the second divided image G2 from the second gamma processing unit 42, and the boundary image G3 from the two-dimensional low-pass filter 60. Then, the combined image signal is output to the display unit 20.

  The display unit 20 displays an image based on the image signal from the image composition unit 50.

  Next, the user confirms this image display, determines the range of the image to be subjected to the smoothing process on the boundary portion between the first divided image G1 and the second divided image G2, and the necessity of the smoothing process. Determine the presence or absence.

  That is, for example, when the user feels that the image is deteriorated because the range of the smoothing process is too wide, for example, the user reduces the range of the image to be smoothed with respect to the operation unit 90. Perform the operation.

  Then, the microcomputer 4 outputs a control command for reducing the range of the image to be smoothed to the two-dimensional low-pass filter 60, and the two-dimensional low-pass filter 60 receives the control command and performs the smoothing processing. Reduce the range of the power image.

  On the other hand, if the range of the smoothing process is too narrow and the user feels that the boundary line of the image has become apparent, the user enlarges the range of the image to be subjected to the smoothing process on the operation unit 90. Perform the operation.

  Then, the microcomputer 4 outputs to the two-dimensional low-pass filter 60 a control command for expanding the range of the image to be smoothed, and the two-dimensional low-pass filter 60 performs the smoothing process in response to this control command. Enlarge the range of power images.

  When the user feels that the smoothing process itself for the boundary image G3 is not necessary, the user performs an operation on the operation unit 90 so that the result of the smoothing process is not reflected. Then, the microcomputer 4 outputs a control command for preventing the result of the smoothing process from being reflected to the image synthesizing unit 50. Upon receiving this control command, the image synthesizing unit 50 does not reflect the result of the smoothing process. Like that.

  According to the ninth embodiment as described above, in addition to the same effects as those of the seventh embodiment, the following effects can be obtained.

  That is, according to the ninth embodiment, by operating the operation unit 90, an image dividing boundary by the image dividing unit 30, an image range on which smoothing processing is performed by the two-dimensional low-pass filter 60, or a two-dimensional low-pass filter The user can arbitrarily set whether the smoothing process 60 is valid / invalid (whether the result is reflected).

  In the ninth embodiment, the image dividing boundary by the image dividing unit 30, the image range subjected to the smoothing process by the two-dimensional low-pass filter 60, and the validity / invalidity of the smoothing process by the two-dimensional low-pass filter 60 are used. In addition to the above, examples in which the user can arbitrarily select and operate have been described, but in addition to these selecting operations, the gamma processing mode in the gamma processing unit 40 can be arbitrarily selected and operated by the user You may do it. That is, for example, when the user operates the operation unit 90, the number of gradations of a dark image can be increased, or the difference between light and dark in an image that is likely to be burned can be reduced. good. If the user can arbitrarily select and operate the gamma processing mode in the gamma processing unit 40, the histogram detection unit 70 may be omitted.

  In the ninth embodiment, the example has been described in which the user can arbitrarily set the position, size, and shape of the frame W serving as the image division boundary. For example, options for the image division boundary are determined in advance. It is also possible to determine the division boundary of the image by performing a selection operation of a desired division boundary from the predetermined options. That is, for example, as shown in FIG. 23 (b), the user selects any one of four divided images (any image within the range of 1 to 3) by operating the operation unit 90, and the selection is performed. The image dividing unit 30 may divide the obtained image.

[Tenth embodiment]
FIG. 26 shows a configuration of a display device 750 according to the tenth embodiment.

  In each of the above sixth to ninth embodiments, the switching unit 7 has been described as being provided upstream of the image dividing unit 30 and the histogram detection unit (histogram detection units 1 and 70). In the embodiment, an example in which the switching unit 7 is arranged at the subsequent stage of the image synthesis unit 50 and the luminance correction unit 2 will be described.

  The display device 750 according to the tenth embodiment is different from the display device 600 according to the sixth embodiment only in the points described below, and otherwise the display device 600 according to the sixth embodiment. In the display device 750 according to the tenth embodiment, the same components as those of the display device 600 are denoted by the same reference numerals, and the description thereof is omitted.

  In the present embodiment, the input image signal branches before the image dividing unit 30 and the histogram detecting unit 1 and is input to the image dividing unit 30 and the histogram detecting unit 1, respectively.

  Then, the gamma processing by the image dividing unit 30, the histogram detecting unit 1, the gamma processing unit 40, the two-dimensional low-pass filter 60, the image synthesizing unit 50 and the microcomputer 4, and the luminance correction by the histogram detecting unit 1, the luminance correcting unit 2 and the microcomputer 4 are performed. Processing is performed in parallel, and image signals as respective processing results are input from the image synthesis unit 50 and the luminance correction unit 2 to the switching unit 7, respectively.

  However, the switching unit 7 selectively transmits only the image signal input from the luminance correction unit 2 to the display unit 20 in the first operation mode according to the control signal from the microcomputer 4. In the second operation mode, only the image signal input from the image composition unit 50 is selectively transmitted to the display unit 20.

  As a result, in the display unit 20, in the first operation mode, the image display is performed based on the image signal subjected to the luminance correction processing by the histogram detection unit 1, the luminance correction unit 2, and the microcomputer 4. In the operation mode, image display is performed based on an image signal that has been subjected to gamma processing by the image dividing unit 30, the histogram detection unit 1, the gamma processing unit 40, the two-dimensional low-pass filter 60, the image synthesis unit 50, and the microcomputer 4.

  According to the tenth embodiment as described above, the same effect as in the sixth embodiment can be obtained.

  In the tenth embodiment, an example in which a part of the display device 600 according to the sixth embodiment is changed has been described. However, as in the present embodiment, the switching unit 7 is replaced with the image synthesis unit 50 and the luminance correction unit 2. The change placed in the subsequent stage can be similarly applied to the seventh to ninth embodiments.

  In the sixth to tenth embodiments, the example including the switching unit 7 has been described. However, the present invention is not limited to this example, and the switching unit 7 may be omitted. Specifically, for example, gamma processing by the image dividing unit 30, the histogram detection unit 1 (70), the gamma processing unit 40, the two-dimensional low-pass filter 60, the image synthesis unit 50, and the microcomputer 4, and the histogram detection unit 1 (70). In addition, the luminance correction processing by the luminance correction unit 2 and the microcomputer 4 is performed in parallel, and the display unit 20 is alternatively selected from the image synthesis unit 50 or the luminance correction unit 2 in accordance with a control signal from the microcomputer 4. Therefore, the switching unit 7 can be omitted.

  In the sixth to tenth embodiments, the function units (image dividing unit 30, histogram detection unit 1 (70), gamma processing unit 40, two-dimensional low-pass filter 60, image synthesis unit 50, and the like that perform gamma processing are used. Although the microcomputer 4) and the functional units (histogram detection unit 1 (70), luminance correction unit 2 and microcomputer 4) for performing the luminance correction processing have been described as sharing the microcomputer 4 and the histogram detection unit 1 (70), A functional unit that performs gamma processing and a functional unit that performs luminance correction processing may be provided separately with either one or both of the microcomputer 4 and the histogram detection unit 1 (70).

  In the sixth to ninth embodiments, examples of performing gamma processing as nonlinear processing have been described, but other examples of nonlinear processing include, for example, contrast adjustment processing, sharpness adjustment processing, noise reduction, and the like. Processing and color correction processing.

  Further, as the nonlinear processing, any one of gamma processing, contrast adjustment processing, sharpness adjustment processing, noise reduction processing, and color correction processing is performed, and at least any of the divided portions obtained by dividing the image into a plurality of portions. It may be performed on one image (preferably, individually on each divided image), or two or more processes may be performed.

  In the sixth to ninth embodiments, the example in which the luminance level distribution is detected in the form of a histogram has been described. In short, it is only necessary that the statistical distribution of the luminance level can be recognized. It is good also as making a statistical graph and detecting.

  Furthermore, as described in the sixth to tenth embodiments, by using the image dividing unit 30 and the image synthesizing unit 50, after the division by the image dividing unit 30 and before the composition by the image synthesizing unit 50, The configuration for performing image processing on an image signal is not limited to performing nonlinear processing (such as gamma processing), but can be similarly applied to performing luminance correction processing. That is, for example, as described in the second to fourth embodiments, when the luminance level distribution is detected for a part of the display area of one display screen and the luminance level in the display area is corrected, for example, The image dividing unit 30 may be disposed before the histogram detecting unit 1 and the image combining unit 50 may be disposed after the luminance correcting unit 2. Further, in that case, if necessary, the histogram detection unit 1 and the luminance correction unit 2 may be separately provided in each transmission path of the image signal after the image division unit 30. Further, when performing the luminance correction processing as in the second to fourth embodiments, when the image dividing unit 30 and the image synthesizing unit 50 are provided, as described in the sixth to tenth embodiments. It is also preferable to provide a two-dimensional low-pass filter (boundary image processing means) 60. In this case, the boundary between the images to be synthesized can be smoothed.

[Eleventh embodiment]
FIG. 27 is a block diagram showing the configuration of the display device 1100 according to the eleventh embodiment, and FIGS. 28 to 30 are diagrams for explaining the operation of the display device 1100.

  For example, in a display device including a display unit such as a plasma display panel, the temperature of the display panel becomes very high when high-luminance image display is continuously performed. That is, as the time for displaying an image with a large APL becomes longer, the temperature of the display panel increases. When the temperature of the display panel reaches a certain level or more, there is a possibility that an adverse effect such as a destruction phenomenon such as cracking of the display panel or a change in electrical characteristic value due to a temperature rise may occur.

  Therefore, in the eleventh embodiment, as shown in FIG. 28, the display position of the white level image G1102 is detected from the entire display screen G1101 of the display unit 20, and the display of the white level image G1102 is further detected. Whether or not the mode is a display mode that satisfies a predetermined condition is determined based on the detection result by the histogram detection unit 1, and when the display in the display mode that satisfies the predetermined condition continues for a predetermined time β or more, display It is determined that the panel is adversely affected, and the luminance correction unit 2 performs the luminance level correction operation.

  In order to realize such an operation, the display device 1100 according to the eleventh embodiment includes, in addition to the components of the display device 100 (FIG. 1) according to the first embodiment, as shown in FIG. The image position detection unit 1101, the timer 1103, and the screen size information output unit 1102 are configured.

  In the display device 1100 according to the present embodiment, the image signal branches, for example, before the histogram detection unit 1 and the image position detection unit 1101, and is input to the histogram detection unit 1 and the image position detection unit 1101, respectively. .

  As in the first embodiment, the histogram detection unit 1 detects the luminance level distribution for the entire display screen G1101 (FIG. 28) and sends the detection result (detection data) as shown in FIG. Output to.

  In the case of the present embodiment, for example, as shown in FIG. 30, it is only necessary to count the number of white level pixels and the number of black level pixels, and it is not necessary to count the intermediate level pixels.

  The image position detection unit 1101 detects the display position of the white level image G1102 from the entire display screen G1101 of the display unit 20, and outputs the detection result (detection data) to the microcomputer 4.

  Specifically, the detection operation by the image position detection unit 1101 is performed as described below, for example.

  That is, the image position detection unit 1101 is, for example, the pixel at the upper left position P3 in the display screen G1101 shown in FIG. 28 → the pixel located one lower level → the pixel located one lower level → The operation for determining the brightness level is repeated until a pixel whose brightness level is determined to be the white level is detected in order. Further, even if the determination operation is performed up to the bottom pixel, if there is no white level pixel, the same determination operation is performed in order from the uppermost pixel for the pixel column on the right side by one column.

  In order to determine whether a pixel is at the white level, an arbitrary luminance level included in the white level is set as a threshold value in advance. The determination is performed by determining whether the luminance level of the pixel exceeds the threshold value.

  As a result of repeating such a determination operation, for example, it is assumed that a determination result indicating that it is the white level is obtained for the first time by the determination operation for the pixel at the position P1 shown in FIG. Then, the image position detection unit 1101 recognizes the position P1 as the start point position of the white level image G1102, and stores it.

  Subsequently, the image position detection unit 1101 has, for example, the luminance in the order of the pixel at the lower right position P4 on the display screen G1101 → the pixel located one higher level → the pixel located one higher level → The brightness level determination operation is repeated until a pixel whose level is determined to be a white level is detected. Further, even if the determination operation is performed up to the uppermost pixel, if there is no white level pixel, the same determination operation is sequentially performed on the pixel column on the left side by one column in order from the lowermost pixel.

  As a result of repeating such a determination operation, for example, it is assumed that a determination result indicating that it is the white level is obtained for the first time by the determination operation for the pixel at the position P2 shown in FIG.

  Then, the image position detection unit 1101 recognizes this position P2 as the end point position of the white level image G1102, and stores it.

  Subsequently, the image position detection unit 1101 recognizes an image in a rectangular area whose two vertices positioned diagonally are at a position P1 and a position P2 as a white level image G1102.

  For example, the image position detection unit 1101 detects the display position and the number of display areas (the number of pixels included in the display area) of the white-level image G1102 in this way.

  In the microcomputer 4, the detection result by the image position detection unit 1101 and the detection result by the histogram detection unit 1 are compared, and the display mode of the white level image G1102 may have an adverse effect such as a broken display panel. It is determined whether or not the display mode satisfies such a predetermined condition.

  That is, the determination is performed according to the number of white level pixels included in the white level image G1102, the ratio of white level pixels included in the white level image G1102, and the like.

  Then, the microcomputer 4 determines that there is a possibility that an adverse effect such as breakage of the display panel may occur when the state determined to be the display mode satisfying the predetermined condition continues for a predetermined time β or more, and the luminance In order to perform the level correction operation, control data is transmitted to the luminance correction unit 2. Note that the timing operation for the predetermined time β is performed based on the timing information input from the timer 1103 to the microcomputer 4.

  When the control data is transmitted from the microcomputer 4 to correct the brightness level, the brightness correction unit 2 corrects the brightness level of the input image signal input via the histogram detection unit 1.

  Here, not only the detection result by the image position detection unit 1101 but also the detection result by the histogram detection unit 1 is used for determining whether or not there is a possibility of adverse effects on the display panel for the following reason.

  That is, in the detection operation by the image position detection unit 1101, as an extreme example, as shown in FIG. 29, for example, even when all the pixels included in the white level image G1102 are at the white level as shown in FIG. Even when only the positions P1 and P2 detected as the start point and the end point are at the white level, the same detection result can be obtained.

  For example, if the display state continues to have a certain number of white level pixels as shown in FIG. 28, it is necessary to correct the luminance level. However, if there are almost no white level pixels as shown in FIG. There is no need to correct the brightness level.

  Therefore, by using the detection result by the histogram detection unit 1, it is possible to make an appropriate determination by the microcomputer 4, and it is possible to prevent an unnecessary correction operation from being performed.

  By the way, for example, in the case of a display device configured to be able to selectively switch the screen size (the size of the area used for image display in the entire display screen G1101) according to the user's operation, the image as described above. In the determination using only the detection results by the position detection unit 1101 and the histogram detection unit 1, there are cases where an appropriate determination cannot be made.

  That is, for example, when a small screen size is selected, the image actually displayed on the display screen G1101 is compressed smaller than the image size indicated by the image signal. There is no need to do it.

  Therefore, in the case of the present embodiment, for example, screen size information indicating the screen size (the size of the area used for image display in the entire display screen G1101) that is selectively switched according to the user's operation is output. The microcomputer 110 outputs the data to the microcomputer 4. The microcomputer 4 performs correction according to the screen size information and performs the above determination operation.

  As a result, the microcomputer 4 can perform more appropriate determination, and can prevent unnecessary correction operations from being performed.

  According to the eleventh embodiment as described above, the display unit 20 (display panel) can be prevented from becoming high temperature, and the occurrence of adverse effects such as breakage of the display panel can be suppressed.

  In the eleventh embodiment described above, an example has been described in which the occurrence of an adverse effect is suppressed by correcting the luminance level when it is determined that the display panel has a bad influence such as breaking, but this is not the only example. Instead, for example, nonlinear processing (see the sixth embodiment or the like) may be performed.

  In the eleventh embodiment, the example has been described for the purpose of suppressing the occurrence of adverse effects such as breakage of the display panel. However, by appropriately changing the determination condition, the eleventh embodiment can be compared with the eleventh embodiment. The display device 1100 having the same configuration can also prevent screen burn-in as in the first to tenth embodiments described above. Conversely, also in the first to tenth embodiments described above, by appropriately changing the determination conditions, it is possible to suppress the occurrence of adverse effects such as breakage of the display panel.

  In the eleventh embodiment, the histogram detection unit 1 and the image position detection unit 1101 are configured separately, and image signals are input in parallel to the histogram detection unit 1 and the image position detection unit 1101. However, the histogram detection unit 1 and the image position detection unit 1101 may be configured by the same IC, for example. In this case, for example, a histogram detection process and an image position detection process are performed in parallel using one system of image signals input to the ICs constituting the histogram detection unit 1 and the image position detection unit 1101. Or sequentially in any order.

  In addition, when the histogram detection unit 1 and the image position detection unit 1101 are configured separately, one of the histogram detection unit 1 and the image position detection unit 1101 is disposed in the front stage and the other is disposed in the rear stage. Image signals may be sequentially input to the histogram detection unit 1 and the image position detection unit 1101 in any order.

  In the eleventh embodiment, the example in which the display device 1100 includes the screen size information output unit 1102 has been described. However, in the case of a display device having a fixed screen size, the screen size information output unit 1102 needs to be provided. Absent.

  In each of the above embodiments, the plasma display device is exemplified as the display device. However, the present invention is not limited to this example, and can be applied to other display devices.

It is a block diagram which shows the structure of the display apparatus which concerns on 1st Embodiment. It is a figure for demonstrating operation | movement, among these, (a) shows an example of the image displayed on a screen, (b) shows the luminance level distribution made into the histogram in case an image is (a). It is a figure which shows an example of the luminance level distribution made into histogram. It is a figure which shows an example of the luminance level distribution made into histogram. It is a figure which shows an example of the luminance level distribution made into histogram. It is a figure which shows an example of the luminance level distribution made into histogram. It is a figure which shows an example of the luminance level distribution made into histogram. It is a figure which shows an example of the luminance level distribution made into histogram. It is a figure which shows an example of the luminance level distribution made into histogram. It is a flowchart which shows the main control flows which the display apparatus of FIG. 1 performs. It is a block diagram which shows the structure of the display apparatus of the modification of FIG. It is a figure for demonstrating the operation | movement in the case of 2nd Embodiment, (a) shows an example of the image displayed on a screen among these, (b) is histogram-ized when an image is (a) The luminance level distribution is shown. Similarly to FIG. 12, (a) shows another example of an image displayed on the screen, and (b) shows a histogram-like luminance level distribution when the image is (a). It is a block diagram which shows the structure of the display apparatus which concerns on 3rd Embodiment. It is a block diagram which shows the structure of the display apparatus which concerns on 4th Embodiment. It is a flowchart which shows the main control flows which the display apparatus of FIG. 15 performs. It is a figure for demonstrating the brightness | luminance level correction | amendment in the case of 5th Embodiment, (a) is a figure which shows a screen display when the display area R2 around the display area R1 of a white level is all black. (B) is a figure which shows a screen display when the display area R2 around the display area R1 of a white level is all white. It is a figure which shows an example of the correction curve used for the brightness | luminance level correction | amendment in the case of 5th Embodiment. It is a block diagram which shows the structure of the display apparatus which concerns on 6th Embodiment. It is a figure which shows another example of the method of the division | segmentation of the image in the case of 6th Embodiment. It is a block diagram which shows the structure of the display apparatus which concerns on 7th Embodiment. It is a block diagram which shows the structure of the display apparatus which concerns on 8th Embodiment. FIG. 23 is a diagram for explaining the operation of the display device of FIG. 22. It is a block diagram which shows another example of a structure of the display apparatus which concerns on 8th Embodiment. It is a block diagram which shows the structure of the display apparatus which concerns on 9th Embodiment. It is a block diagram which shows the structure of the display apparatus which concerns on 10th Embodiment. It is a block diagram which shows the structure of the display apparatus which concerns on 11th Embodiment. It is a figure for demonstrating operation | movement of the display apparatus which concerns on 11th Embodiment. It is a figure for demonstrating operation | movement of the display apparatus which concerns on 11th Embodiment. It is a figure for demonstrating operation | movement of the display apparatus which concerns on 11th Embodiment. It is a block diagram which shows the structure of the conventional display apparatus.

Explanation of symbols

1 Histogram detection unit (luminance level distribution detection means)
2 Luminance correction unit (luminance correction means)
10 Burning reduction part (image processing device)
20 Display unit 4 Microcomputer (luminance correction means, detection area change means, designated data rewrite means, operation mode selection means)
a first threshold value b second threshold value c third threshold value d fourth threshold value e fifth threshold value 100 display device 5 timer (luminance correction means)
150 Display 1A Histogram detector (luminance level distribution detector)
300 display device 6 storage unit (detection area changing means, storage means)
400 display device 7 switching unit (operation mode selection means)
30 Image segmentation unit (image segmentation means)
40 Gamma processing unit (non-linear processing means)
41 First gamma processing unit 42 Second gamma processing unit 50 Image composition unit (image composition means)
60 Two-dimensional low-pass filter (boundary image processing means)
600 Display device 70 Histogram detection unit (luminance level distribution detection means)
71 First Histogram Detection Unit 72 Second Histogram Detection Unit 700 Display Device 43 Third Gamma Processing Unit 44 Fourth Gamma Processing Unit 800 Display Device 850 Display Device 90 Operation Unit (Boundary Line Designation Operation Means, Smoothing Processing Valid / Invalid Selection Operation means, non-linear processing designation operation means)
900 display device 750 display device 1100 display device 1101 image position detection unit (image position detection means)

Claims (6)

In an image processing apparatus that performs image processing on an image displayed on a display screen,
A luminance level distribution detecting means for detecting a statistical distribution of the number of pixels for each luminance level of pixels included in an image with respect to an entire display screen based on an input image signal;
Brightness correction means for correcting the brightness level of the input image signal in accordance with the number of pixels for each brightness level detected by the brightness level distribution detection means;
Equipped with a,
The luminance level distribution detecting means includes at least a black level composed of a plurality of low gradations including the minimum gradation, a white level composed of a plurality of high gradations including the maximum gradation, and the number of gradations therebetween. The statistical distribution of the number of pixels for each of the three intermediate brightness levels is detected,
The luminance correction means, according to the number of pixels for each of the three luminance levels, the size relationship of the number of pixels of the three luminance levels, and the number of pixels of a specific luminance level among the luminance levels included in the white level, The image processing apparatus according to claim 1, wherein the luminance level of the input image signal is corrected, and the specific luminance level is a luminance level at which the number of pixels peaks in the statistical distribution of the number of pixels of the white level . The brightness correction means includes
A first condition that the number of pixels of the white level is larger than a first threshold and smaller than a second threshold;
A second condition that the number of pixels at the intermediate level is smaller than a third threshold;
A third condition that the number of pixels of the black level is larger than the intermediate level;
A fourth condition that the number of pixels of the black level is larger than the white level;
If the condition D is satisfied ,
Any of a fifth condition that the number of pixels of the black level is larger than a fourth threshold value and a sixth condition that the number of pixels of the intermediate level is larger than the fourth threshold value Satisfy either
and,
When the condition E is satisfied when the seventh condition that the number of pixels of the specific luminance level among the luminance levels included in the white level is larger than a fifth threshold is satisfied,
The third threshold is greater than the second threshold and less than the fourth threshold; the fifth threshold is greater than the second threshold; and Less than the third threshold,
When the condition D or the condition E is satisfied, the luminance level of the input image signal is corrected, and when neither the condition D nor the condition E is satisfied, the luminance level of the input image signal is not corrected. The image processing apparatus according to claim 1 . The luminance correction means corrects the luminance level of the input image signal when a state in which the statistical distribution of the luminance level is a distribution for which the luminance level is to be corrected continues for longer than a predetermined time. The image processing apparatus according to claim 1 or 2 . The luminance correction unit, the image processing apparatus according to any one of claims 1 to 3, characterized in that the correction by lowering the brightness of the input image signal. The luminance correction unit, the image processing apparatus according to any one of claims 1 to 4, characterized in that the correction by lowering the luminance of the pixels of the white level. The luminance correction unit, among the luminance levels included in the white level, in any one of claims 1 to 5, characterized in that the correction by lowering the luminance of the pixels of a specific luminance level The image processing apparatus described.