JP4014976B2 - Display device and gamma correction method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
This invention relates to a display relates to an apparatus and γ correction how relates especially display device and γ correction how to perform the appropriate γ correction on the image signal output from the image generating apparatus connected.
[0002]
[Prior art]
The display device has a gradation response characteristic in which the gradation of an output image changes exponentially without being directly proportional to the input voltage, and this response characteristic is represented by a γ value. In consideration of the response characteristics of the display device, the image signal is subjected to γ correction. When the display device is connected to a personal computer (image signal generation device) that generates an image signal, γ correction in consideration of the γ value of the display device is executed by the personal computer. In a personal computer, generally, assuming that the γ value of the display device is 2.2, for example, the image signal after γ correction is γ-corrected so that the γ value of the image signal is 1/22, Outputting to the display device.
[0003]
However, there is no problem when a predetermined display device and a personal computer are connected, but when the display device is connected with a different personal computer, the γ value of γ correction executed by the personal computer is displayed on the display device. May not correspond to the γ value. In such a case, the γ value of the image finally output from the display device does not become 1. For example, the γ value of γ correction executed by a personal computer is 1 / 2.5, and the γ value of the display device is 2.2.
[0004]
In order to solve this problem, Japanese Patent Laid-Open No. 2001-34245 describes a technique of adding screen adjustment control information including a γ value for γ correction to an image signal output from a personal computer and outputting the image signal to a display device. According to this, if the γ value of the screen adjustment control information added to the image signal is detected on the display device side, it is possible to detect what γ correction has been executed by the personal computer.
[0005]
[Patent Document 1]
JP 2001-34245 A
[0006]
[Problems to be solved by the invention]
However, since the technique described in Japanese Patent Laid-Open No. 2001-34245 needs to provide a special image signal generator for adding screen adjustment control information to an image signal on the personal computer side, it is necessary to modify the personal computer itself. Yes, an existing personal computer cannot be used. For this reason, when the connected personal computer does not output the screen adjustment control information added to the image signal, the γ value of the γ correction executed by the personal computer cannot be detected, and the display device has an appropriate level. The image cannot be displayed in the key.
[0007]
The present invention has been made to solve the above-described problems, and one of the objects of the present invention is to provide an appropriate γ correction regardless of the case where any γ correction is performed in the connected image signal generator. It is providing the display apparatus which can perform.
[0008]
Another object of the present invention is to provide a γ correction capable of performing a γ correction suitable for output by a display device, regardless of what γ correction is performed by an image signal generator connected to the display device. Is to provide a method.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, according to one aspect of the present invention, a display device is a display device that displays an image signal input from the outside , and a storage unit that previously stores a γ value of the display device; Receiving means for receiving an image signal from an image signal generating device connected to the display device, a voltage value for each region of the specific pattern is stored in advance, and the specific pattern received by the receiving means using the voltage value stored in advance Γ value detecting means for detecting the γ value of the image signal, computing means for calculating a correction value from the detected γ value and the γ value of the display device stored in the storage means, and reception according to the calculated correction value Γ correction means for γ correcting the image signal received by the means.
[0011]
According to the present invention, the voltage value for each region of the specific pattern received from the image signal generator connected to the display device is stored in advance , and the γ value of the image signal of the specific pattern is stored using the pre-stored voltage value. Is detected. For this reason, it is possible to detect the γ value of the γ correction performed in the image signal generator only by receiving an image signal of a specific pattern from the connected image signal generator. Then, a correction value is calculated from the detected γ value and the γ value of the display device, and the image signal received from the image signal generator is γ-corrected according to the calculated correction value. As a result, it is possible to provide a display device capable of performing appropriate γ correction even when any γ correction is performed in the connected image signal generation device.
[0012]
According to another aspect of the present invention, a γ correction method is a γ correction method for a display device that displays an image signal input from the outside, and an image of a specific pattern is received from an image signal generator connected to the display device. A step of receiving a signal; a step of storing a voltage value for each region of the specific pattern in advance; and a step of detecting a γ value of the received image signal of the specific pattern using the pre-stored voltage value; A calculation step of calculating a correction value from the value and the γ value of the display device, and a step of γ correcting the image signal received from the image signal generating device according to the calculated correction value.
[0013]
According to the present invention, there is provided a γ correction method capable of performing γ correction suitable for output by a display device, regardless of what γ correction is performed by an image signal generation device connected to the display device. Can be provided.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.
[0017]
FIG. 1 shows the appearance of a display device and an image signal generator connected thereto in an embodiment of the present invention. As will be described below, the image signal generator is configured by a general personal computer.
[0018]
Referring to FIG. 1, display device 200 is connected to personal computer 100 that is an image signal generation device. The display device 200 is a liquid crystal display device, a CRT, a plasma display, an electroluminescence or a field emission display. The personal computer 100 includes a CD-ROM (Compact Disc Read-Only Memory) drive 110, an FD (Flexible Disk) drive 112, a keyboard 106 and a mouse 108. A CD-ROM is mounted on the CD-ROM drive 110. An FD is attached to the FD drive 112.
[0019]
An image signal having a specific pattern, which will be described later, is recorded on the FD or CD-ROM, and is read by the FD drive 112 or the CD-ROM drive 110. Then, the read image signal of the specific pattern is output from the personal computer 100 to the display device 200.
[0020]
The personal computer 100 executes γ correction on the read image signal of the specific pattern. In the personal computer 100, a γ value for γ correction is determined in advance. Here, for the sake of explanation, a description will be given assuming that correction is performed so that the γ value of the image signal after γ correction is 1/2. Note that some personal computers connected to the display device 200 do not execute γ correction. In that case, it may be considered that γ correction with a γ value of 0 is executed.
[0021]
Since the operation of personal computer 100 itself is well known, detailed description thereof will not be repeated here.
[0022]
FIG. 2 is a functional block diagram showing functions of the display device 200 in the present embodiment. In FIG. 2, functions of the personal computer 100 are also illustrated for explanation. Referring to FIG. 2, display device 200 detects reception unit 202 for receiving an image signal from personal computer 100, storage unit 203 for storing monitor γ value 203a, and γ value of the image signal of a specific pattern. A correction value calculation unit 205 that calculates a correction value from the γ value of the image signal of the specific pattern and the monitor γ value, and a correction value calculated from the image signal received from the personal computer 100 The monitor correction unit 207 that performs γ correction according to the above and the display unit 211 that displays the gamma-corrected image signal.
[0023]
The personal computer 100 includes an image signal generation unit 101 and a γ correction unit 102. The image signal generating unit 101 generates an image signal of an image created by application software activated by the personal computer 100. Further, an image signal is generated by reading an image recorded on a recording medium such as an FD or a CD-ROM with the FD drive 112 or the CD-ROM drive 110. Further, the image signal generator 101 can receive an image signal input to the personal computer 100 from another computer connected to the personal computer, a digital camera, a digital video camera, or the like. Such an image signal can be generated if it is a broken image signal. Then, the image signal generation unit 101 outputs the generated image signal to the γ correction unit 102.
[0024]
In particular, the image signal generation unit 101 generates an image signal of a specific pattern by reading the specific pattern 103 from an FD or CD-ROM storing a specific pattern described later.
[0025]
The γ correction unit 102 γ corrects the input image signal. Here, the γ correction is a correction in consideration of the γ value of the display device 200, but this γ value is predetermined in the personal computer 100 and does not necessarily correspond to the γ value of the display device 200. . Here, the γ value of γ correction executed by the γ correction unit 102 is described as 1 / 2.5.
[0026]
FIG. 3 is a diagram illustrating an example of the specific pattern. Referring to FIG. 3, in the specific pattern, each of the three primary colors of red (R), green (G), and blue (B) is represented in a strip shape, and the gradation of each color is higher on the right side in the figure and on the left side. The pattern is low. Actually, the pattern is divided into a plurality of regions, and the gradation changes stepwise. This will be described more specifically.
[0027]
FIG. 4 is a diagram for explaining the divided areas of the specific pattern shown in FIG. Referring to FIG. 4, the specific pattern is divided into 48 regions by dividing into 3 parts in the vertical direction and 16 parts in the horizontal direction. Upper 16 regions R0 to R1 5 red (R), the middle region G0~G15 green (G), the lower region B0~B15 corresponds to blue (B). The gray level is lower in the left area in the figure and higher in the right area. Specifically, the gradations of the regions R0, R1, R3,..., R15 are 0, 16, 32,. The gradation is similarly defined for the regions G0 to G15 and the regions B0 to B15. Thus, the specific pattern defines the gradation for each position in the image. In particular, in the present embodiment, the pattern is such that the gradation increases stepwise from the left to the right in the drawing. Thereby, in the display device 200, when an image signal of a specific pattern is input, an input voltage value can be associated with each region. That is, the input voltages V0, V1, V2,... V15 can be made to correspond to the regions R0, R1, R2,. This input voltage is determined based on the relationship between the gradation and the input voltage when the γ value is 1.
[0028]
Here, the region is divided into 16 equal parts, and each gradation value divided into 16 parts is assigned to each region. However, the number of divisions is not limited to this, and the later-described γ value increases as the number of divisions increases. Detection accuracy can be improved. However, if the number of divisions is increased, the amount of calculation for γ detection increases, and therefore an appropriate number of divisions may be set according to the processing speed of the display device 200, the amount of memory, and the like.
[0029]
FIG. 5 is a diagram illustrating another example of the specific pattern. Another specific pattern is different from the pattern of the three primary colors of RGB described above only in that it is expressed in gray scale instead of the three primary colors. Since other configurations are not different from the above-described three primary color patterns, the description will not be repeated. In the display device 200 according to the present embodiment, the specific patterns shown in FIG. 3 or FIG. 5 are input. For example, which specific pattern is input is determined by, for example, the OSD ( On
Specified by the user using the Screen Display function.
[0030]
Returning to FIG. 2, the receiving unit 202 of the display device 200 receives an image signal output from the personal computer 100. The image signal received by the reception unit 202 is normally output to the monitor correction unit 207, but when the input of a specific pattern is instructed by the OSD function described above and execution of the γ value correction process is instructed. The received image signal of the specific pattern is output to the γ value detection unit 201.
[0031]
When receiving a specific pattern image signal from the personal computer 100, the γ value detection unit 201 detects the γ value of the specific pattern image signal. As described above, the input voltage is defined corresponding to each region of the specific pattern. The γ value detection unit 201 stores in advance a voltage corresponding to each region of the specific pattern. The stored voltage value is a voltage value corresponding to the gradation of each region when an image signal having a specific pattern with a γ value of 1 is received. Then, the γ value of the image signal of the specific pattern is obtained by associating the voltage corresponding to each region of the specific pattern with the gradation of the received image signal.
[0032]
FIG. 6 is a diagram illustrating a γ value of an image signal having a specific pattern output from a personal computer. FIG. 6 shows a graph in which the horizontal axis is the input voltage (V) and the vertical axis is the gradation (L). By plotting the gradation for each area of the specific pattern corresponding to the input voltage defined corresponding to the area, the γ curve in the figure is obtained, and the γ value is obtained. As for the gradation for each region of the specific pattern, noise included in the image signal can be removed by extracting a plurality of sample values from one region of the image signal and using the average value or the intermediate value thereof. Therefore, the detection accuracy of the γ value can be improved. Further, if the number of divisions of the specific pattern in the gradation direction is increased, the number of points to be plotted increases, so that the γ value detection accuracy can be improved. Hereinafter, the γ value detected by the γ value detection unit 201 is referred to as γ1.
[0033]
FIG. 7 is a diagram showing a γ curve of display device 200 in the present embodiment. The γ value (γ2) of the display device 200 was 2.2. For this reason, the gradation changes gently at a portion where the input voltage is low, and the gradation changes abruptly at a portion where the input voltage is high.
[0034]
FIG. 8 is a diagram illustrating a γ curve when an image signal received from a personal computer is output without γ correction. When an image signal that has been subjected to γ correction with a γ value (γ1) of 1 / 2.5 on a personal computer is output from a display device with a γ value of γ2 = 2.2, the total γ value is 2.2 / 2. .5 and not 1. For this reason, the gradation cannot be accurately reproduced on the display device 200. In the present invention, the monitor correction unit 207 corrects the input image signal so that the total γ value becomes 1.
[0035]
Returning to FIG. 2, the correction value calculation unit 205 calculates a correction value from the monitor γ value 203 a stored in the storage unit 203 and γ1 detected by the γ value detection unit 201. This correction value is represented by (1− (γ1 × γ2)), where the monitor γ value 203a is γ2. Since γ2 = 2.2 and γ1 = 1 / 2.5, the correction value is (1−2.2 / 2.5).
[0036]
The correction value calculated by the correction value calculation unit 205 is output to the monitor correction unit 207. The monitor correction unit 207 performs γ correction on the image signal received from the personal computer 100 according to the received correction value. This γ correction is performed by a conventionally known technique such as a method of changing the look-up table 209 provided in the correction value calculation unit 205 according to the correction value, or a method of changing the image signal received from the personal computer 100 according to the correction value. Can be used. Therefore, detailed description thereof will not be repeated.
[0037]
The γ value of the image signal output from the monitor correction unit 207 to the display unit 211 is 1 / 2.2 because the monitor γ value 203a is γ2 = 2.2. As a result, an image signal subjected to appropriate γ correction is input to the display unit 211, so that gradation can be expressed with high accuracy.
[0038]
In addition, the γ value detection unit 201, the correction value calculation unit 205, and the monitor correction unit 207 of the display device 200 may be realized by hardware or may be realized by executing software by a CPU. When the software is realized by executing it by the CPU, the γ correction program is stored in a memory such as a ROM of the display device 200, and the γ correction program is executed by the CPU. Further, the ROM 215 may be detachable from the display device 200, and when the ROM 215 is mounted on the display device 200, the γ correction program stored in the ROM 215 may be read and executed by the CPU of the display device 200. .
[0039]
The recording medium for storing the γ correction program is not limited to the ROM, but a magnetic tape, cassette tape, optical disk (MO (Magnetic Optical Disc) / MD (Mini Disc) / DVD (Digital Versatile Disc)), IC card ( (Including a memory card), an optical card, a mask ROM, an EPROM, an EEPROM, a semiconductor memory such as a flash ROM, or a medium that carries a fixed program.
[0040]
The program here is a concept including not only a program directly executable by the CPU but also a program in a source program format, a compressed program, an encrypted program, and the like.
[0041]
FIG. 9 is a flowchart showing the flow of the γ value adjustment process executed by the display device 200 of the present embodiment. The display device 200 starts the γ value adjustment process by the user selecting a menu instructing execution of the γ value adjustment process from the menus displayed on the display unit 211 by the OSD function included in the display device 200. This is the case. Further, when the gamma value adjustment process is started by the display device 200, the specific pattern is read from the FD or CD-ROM in which the specific pattern 103 is recorded by the personal computer 100, and the image signal of the specific pattern is read from the personal computer 100. Needs to be output to the display device 200.
[0042]
Referring to FIG. 9, display device 200 receives an image signal of a specific pattern from personal computer 100 (step S01). Then, with respect to the received image signal of the specific pattern, the gray level of each area is associated with an input voltage predetermined corresponding to the area, thereby obtaining a γ value (γ1 = 1/2. 5) is detected (step S02).
[0043]
A correction value (1-γ1 × γ2) is calculated from the γ value (γ2 = 2.2) of the display device 200 and the γ value of the detected image signal of the specific pattern (step S03). Based on the calculated correction value, the lookup table 209 used for γ correction is changed (step S04). In step S04, the lookup table 209 is changed. However, the coefficient for correcting the received image signal may be changed according to the correction value. This completes the γ value adjustment process.
[0044]
FIG. 10 is a flowchart showing a flow of processing in which the display device displays an image signal received from a personal computer. Referring to FIG. 10, when receiving an image signal from personal computer 100 (step S11), display device 200 performs γ correction using a look-up table changed according to the correction value (step S12). Then, the γ-corrected image signal is displayed on the display unit 211 (step S13). Thus, since the look-up table 209 is changed after the γ value adjustment processing is performed, the changed look-up table 209 is used for an image signal input from the personal computer 100 thereafter. Γ correction is performed. Therefore, an image can be displayed on the display unit 211 with an appropriate gradation.
[0045]
This γ value adjustment process may be executed once when the display device 200 is connected to the personal computer 100 as an image signal generator. Therefore, it is sufficient to execute the display device 200 once every time the display device 200 is connected to the image signal generator.
[0046]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
[Brief description of the drawings]
FIG. 1 is a diagram showing an external appearance of a display device and an image signal generator connected to the display device in an embodiment of the present invention.
FIG. 2 is a functional block diagram showing functions of a display device 200 in the present embodiment.
FIG. 3 is a diagram illustrating an example of a specific pattern.
FIG. 4 is a diagram for explaining a divided area of a specific pattern;
FIG. 5 is a diagram illustrating another example of the specific pattern.
FIG. 6 is a diagram illustrating a γ value of an image signal of a specific pattern output from a personal computer.
FIG. 7 is a diagram showing a γ curve of the display device in the present embodiment.
FIG. 8 is a diagram illustrating a γ curve when an image signal received from a personal computer is output without γ correction.
FIG. 9 is a flowchart showing a flow of γ value adjustment processing executed by display device 200 of the present embodiment.
FIG. 10 is a flowchart showing a flow of processing for displaying an image signal received by a display device from a personal computer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 Personal computer, 101 Image signal generation part, 102 γ correction part, 103 Specific pattern, 106 Keyboard, 108 Mouse, 110 CD-ROM drive, 112 FD drive, 200 Display device, 201 γ value detection part, 203 Storage part, 203a Monitor γ value, 205 correction value calculation unit, 207 monitor correction unit, 209 lookup table, 211 display unit.

Claims (2)

A display device for displaying an image signal input from the outside,
Storage means for storing in advance the γ value of the display device;
Receiving means for receiving an image signal from an image signal generator connected to the display device;
A voltage value for each region of the specific pattern is stored in advance, and using the voltage value stored in advance, a γ value detecting unit that detects a γ value of the image signal of the specific pattern received by the receiving unit;
Arithmetic means for calculating a correction value from the detected γ value and the γ value of the display device stored in the storage means ;
A display device comprising: γ correction means for γ correcting the image signal received by the receiving means in accordance with the calculated correction value. A gamma correction method for a display device that displays an image signal input from the outside,
Receiving an image signal of a specific pattern from an image signal generator connected to the display device;
Pre-store voltage values for each region of the specific pattern, and using the pre-stored voltage values to detect the γ value of the received image signal of the specific pattern;
A calculation step of calculating a correction value from the detected γ value and the γ value of the display device;
Gamma correcting the image signal received from the image signal generating device according to the calculated correction value .

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