JP6137645B2 - Image quality improving apparatus, image display apparatus, and image quality improving method - Google Patents

Description

  The present invention relates to an image quality improvement device, an image display device, and an image quality improvement method, for example, an image quality improvement device, an image display device, and an image quality improvement that improve the image quality of multi-image display in which a plurality of images are displayed side by side in one display image. Regarding the method.

  In an image display device such as a projector, it is known that image quality deteriorates due to the occurrence of flare. Flare is a phenomenon in which light in a bright part in a display image leaks to a dark part due to, for example, reflection or scattering of light on the projection optical system or the projection surface. When flare occurs, an edge portion (for example, a boundary portion between a white region and a black region) having a large luminance difference in the display image is blurred, and the luminance difference between the edge portions is reduced.

  Patent Document 1 describes an image quality improvement device that can suppress a decrease in image quality caused by flare.

  For example, the image quality improvement apparatus described in Patent Document 1 corrects a video signal so that a luminance difference at a boundary portion between a white area and a black area in the video signal is increased (hereinafter referred to as “reduction in image quality due to flare”). Also referred to as “image quality correction for suppression”). For this reason, in an image corresponding to a video signal that has been subjected to image quality correction to suppress degradation in image quality due to flare, even if the luminance difference due to flare decreases at the boundary between the white area and the black area , Deterioration of image quality due to flare is suppressed.

  FIG. 1 is a diagram showing an image quality improvement apparatus 100 described in Patent Document 1. As shown in FIG.

  In FIG. 1, image quality improvement apparatus 100 includes a two-dimensional LPF (low-pass filter) 1, delay compensation units 2 and 3, subtraction unit 4, amplification unit 5, and addition unit 6.

  In the image quality improvement apparatus 100, the luminance signal a is supplied to the two-dimensional LPF 1 and the delay compensation unit 2, and the color difference signal is supplied to the delay compensation unit 3. Hereinafter, the luminance signal is also referred to as “Y signal”, and the color difference signal is also referred to as “C signal”.

  The two-dimensional LPF 1 removes a high frequency component (edge component) from the Y signal a. For this reason, the output of the two-dimensional LPF 1 is a Y signal b with a rounded edge, that is, a low frequency component of the Y signal a.

  The delay compensator 2 delays the Y signal a by the time required for the filter processing in the two-dimensional LPF 1. The delay compensator 3 delays the C signal by the time required for the signal processing of the Y signal in the image quality improving apparatus 100.

  The subtracting unit 4 subtracts the output of the two-dimensional LPF 1 (Y signal b with a missing edge) from the output of the delay compensating unit 2 (Y signal a). The output of the subtracting unit 4 is an edge component signal c representing the high frequency component of the Y signal a.

  The amplifying unit 5 adjusts the amplitude of the edge component signal c from the subtracting unit 4.

  The adder 6 adds the edge component signal d adjusted by the amplifier 5 to the output (Y signal a) of the delay compensator 2. For this reason, the output of the adding unit 6 is a signal e in which the edge of the Y signal a is emphasized, that is, a Y signal that has been subjected to image quality correction for suppressing deterioration in image quality due to flare.

  In the image quality improvement apparatus 100, the two-dimensional LPF 1 can be configured using a recursive filter (see Patent Document 1).

  FIG. 2 is a diagram showing an example of the recursive filter 10 used in the two-dimensional LPF 1.

  In FIG. 2, the recursive filter 10 includes a horizontal recursive filter 10a and a vertical recursive filter 10b.

  The horizontal recursive filter 10a removes a high frequency component (edge component) in the horizontal direction of an image represented by the video signal from the video signal.

  The vertical recursive filter 10b removes a high frequency component (edge component) in the vertical direction of an image represented by the video signal from the video signal.

  FIG. 3 is a diagram showing the horizontal recursive filter 10a.

  In FIG. 3, the horizontal recursive filter 10a includes an amplifying unit 10a1, an adding unit 10a2, a one-pixel period delay unit 10a3, an amplifying unit 10a4, and a feedback line 10a5.

  The amplifying unit 10a1 adjusts the amplitude of the video signal (for example, luminance signal) S.

  Note that the video signal S represents image data (for example, luminance data) in the line in order for each line constituting the image represented by the video signal S.

  FIG. 4 is a diagram illustrating an example of image data in one line of an image represented by the video signal S.

4, the video signal S represents the n image data _S 1 to S _n corresponding to each of the n pixels corresponding to one line in the order of _S 1 to S _n. Note that the switching timing of image data is defined by a dot clock.

  The output of the amplifier 10a1 is supplied to one input of the adder 10a2 shown in FIG. 3, and the output of the amplifier 10a4 is supplied to the other input of the adder 10a2. The adder 10a2 adds the output of the amplifier 10a4 to the output of the amplifier 10a1.

  The one-pixel period delay unit 10a3 is provided in a feedback line 10a5 that feeds back the output of the adder 10a2 to the other input of the adder 10a2. The one-pixel period delay unit 10a3 delays the output of the adder unit 10a2 by a time corresponding to one pixel (pixel) period (one image data period) of the video signal. One pixel period is an example of a predetermined time.

  The amplifying unit 10a4 is provided in the feedback line 10a5. The amplifying unit 10a4 adjusts the amplitude of the output of the one-pixel period delay unit 10a3 in order to weight the output of the one-pixel period delay unit 10a3.

  The horizontal recursive filter 10a sets the image data represented by the video signal as a weighted addition value of the image data and the image data already input in the horizontal period for each pixel period in the horizontal period. Thus, the high frequency component (edge component) in the horizontal direction of the video represented by the video signal is removed from the video signal.

  FIG. 5 is a diagram showing the vertical recursive filter 10b.

  In FIG. 5, the vertical recursive filter 10b includes an amplifying unit 10b1, an adding unit 10b2, a one horizontal period delay unit 10b3, an amplifying unit 10b4, and a feedback line 10b5.

  The amplification unit 10b1 adjusts the amplitude of the video signal (for example, luminance signal) S.

  The output of the amplifying unit 10b1 is supplied to one input of the adding unit 10b2, and the output of the amplifying unit 10b4 is supplied to the other input of the adding unit 10b2. The adder 10b2 adds the output of the amplifier 10b4 to the output of the amplifier 10b1.

  The one horizontal period delay unit 10b3 is provided in a feedback line 10b5 that feeds back the output of the addition unit 10b2 to the other input of the addition unit 10b2. The one horizontal period delay unit 10b3 delays the output of the addition unit 10b2 by one horizontal period of the video represented by the video signal.

  The amplification unit 10b4 is provided in the feedback line 10b5. The amplifying unit 10b4 adjusts the amplitude of the output of the one horizontal period delay unit 10b3 in order to weight the output of the one horizontal period delay unit 10b3.

  The vertical recursive filter 10b displays image data represented by a video signal for each pixel period in one vertical period, the image data, and a multiple of the horizontal period from the input timing of the image data in the one vertical period. By using a weighted addition value of image data that has already been input just before a certain period, a high frequency component (edge component) in the vertical direction of the video represented by the video signal is removed from the video signal.

  In addition, the image display device such as a projector receives a different video signal from each of two video sources (for example, two PCs) and displays an image represented by each video signal on one screen. (See Patent Document 2).

  An image display device having a multi-image display function, for example, when displaying a multi-display image in which two videos are arranged in the horizontal direction (horizontal direction), multi-image display showing a state in which the two videos are arranged in the horizontal direction A video signal is generated, and an image corresponding to the video signal for multi-image display is displayed.

JP 2008-185606 A JP 2012-163665 A

  In an image display device having a multi-image display function as disclosed in Patent Document 2, a video signal for multi-image display representing a state in which each video is arranged in the horizontal direction (horizontal direction) is obtained from two video signals. Generate and display an image according to the video signal for multi-image display.

  On the other hand, an image quality improvement apparatus (hereinafter referred to as “image quality improvement apparatus of related technology”) that performs image quality correction for suppressing deterioration in image quality caused by flare using a recursive filter is provided for each image represented by a video signal. The data is set as a weighted addition value of the image data already input within the horizontal period to which the image data belongs.

  For this reason, when the related art image quality improvement apparatus executes image quality correction for suppressing a decrease in image quality caused by flare on a video signal for multi-image display, two images belonging to the same horizontal direction are processed. Perform continuous weighted addition. Therefore, in an image in which the order in which the image data is input to the cyclic filter is later in the two images, the entire image is affected by the previous image in the order in which the image data is input to the cyclic filter. As a result, the image quality of the entire image is degraded.

  The same problem occurs when displaying an image corresponding to a video signal for multi-image display representing a state in which the images are arranged in the vertical direction (vertical direction).

  An object of the present invention is to provide an image quality improvement apparatus, an image display apparatus, and an image quality improvement method capable of solving at least one of the above problems.

The image quality improving apparatus of the present invention is
A low pass filter that extracts low frequency components from the input video signal;
A subtracting unit for subtracting a low frequency component extracted by the low pass filter from the input video signal to obtain a high frequency component;
An addition unit that performs image quality correction on the input video signal by adding the high-frequency component obtained by the subtraction unit to the input video signal;
The low-pass filter performs a weighted addition process for weighted addition of the input video signal and a delayed signal obtained by giving a delay of a predetermined time to its output, and uses the result of the weighted addition process as the low frequency component Including a recursive filter to output,
Executing the weighted-addition processing using the recursive filter to the image in which the input video signal represents, when said input video signal represents a plurality of images, the weight adding processing using the recursive filter a look including a control unit for executing for each of the plurality of images,
The input video signal represents a composite image in which the plurality of images are arranged in the horizontal direction of the image, and for each of a plurality of lines constituting the composite image, the image data in the line is sequentially represented,
The predetermined time is one image data period;
The control unit detects, for a horizontal period that is a display period of each of the plurality of lines, a boundary timing representing image data in which the input video signal is a boundary of the plurality of images within the horizontal period, For each of a plurality of divided periods obtained by dividing the horizontal period based on a boundary timing, a low frequency component in the horizontal direction of an image represented by the input video signal by executing the weighted addition process using the cyclic filter Extract
The control unit detects the boundary timing based on the division period and the number of image data received in the horizontal period .
An image quality improving apparatus according to another aspect of the present invention
A low pass filter that extracts low frequency components from the input video signal;
A subtracting unit for subtracting a low frequency component extracted by the low pass filter from the input video signal to obtain a high frequency component;
An addition unit that performs image quality correction on the input video signal by adding the high-frequency component obtained by the subtraction unit to the input video signal;
The low-pass filter performs a weighted addition process that weights and adds the input video signal and a delayed signal obtained by giving a delay of a predetermined time to its own output, and outputs the result of the weighted addition process as the low frequency component Including a recursive filter that
The weighted addition process using the cyclic filter is performed on the image represented by the input video signal, and the weighted addition process using the cyclic filter is performed when the input video signal represents a plurality of images. Including a control unit that executes each of the plurality of images,
The input video signal represents a composite image in which the plurality of images are arranged in the vertical direction of the image, and sequentially represents the image data in the line for each of the plurality of lines constituting the composite image,
The predetermined time is one horizontal period;
The recursive filter is
A feedback line that feeds back the output of the cyclic filter to the cyclic filter;
A delay unit that is provided in the feedback line, generates a delay signal by giving a delay of the predetermined time to the output of the cyclic filter, and outputs the delay signal;
An adder that performs weighted addition of the input video signal and the delayed signal received through the feedback line, and outputs a result of the weighted addition as an output of the cyclic filter;
The control unit detects, for a vertical period that is a display period of the composite image, a boundary timing that represents image data in which the input video signal serves as a boundary between the plurality of images within the vertical period, and at the boundary timing The output of the delay signal from the delay unit is temporarily stopped.

The image quality improvement method of the present invention is
An image quality improvement method performed by an image quality improvement device,
Extract low frequency components from the input video signal,
Subtracting the low frequency component from the input video signal to obtain a high frequency component,
By adding the high frequency component to the input video signal, image quality correction is performed on the input video signal,
The low frequency component is extracted by performing a weighted addition process that weights and adds the input video signal and a delayed signal obtained by delaying the output of the input video signal by a predetermined time. Output as a frequency component,
Performing the weighted addition process on the image represented by the input video signal, and when the input video signal represents a plurality of images, performing the weighted addition process for each of the plurality of images;
The input video signal represents a composite image in which the plurality of images are arranged in a vertical direction of the images,
For each of a plurality of lines constituting the composite image, the image data in the lines are represented in order,
The predetermined time is one horizontal period,
For a vertical period that is a display period of the composite image, a boundary timing in which the input video signal represents image data that is a boundary of the plurality of images within the vertical period is detected, and the delay signal is detected at the boundary timing. Stop output temporarily.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to perform the image quality correction with little influence from an adjacent image with respect to each image in the multi-image showing a several image, and the image quality in the whole image in each image in a multi-image. Can be suppressed.

It is the figure which showed the image quality improvement apparatus of patent document 1. FIG. It is the figure which showed an example of the recursive filter 10 used by 2-dimensional LPF1. It is the figure which showed the horizontal recursive filter 10a. It is the figure which showed an example of the image data in 1 line. It is the figure which showed the vertical recursive filter 10b. It is a figure showing picture quality improvement device 100A of one embodiment of the present invention. It is the figure which showed two-dimensional LPF7. FIG. 6 is a diagram showing a recursive filter 700. It is the figure which showed the horizontal recursive filter 700a. It is a figure for demonstrating operation | movement of the detection part 700a2 contained in the horizontal recursive filter 700a in the recursive filter 71. FIG. 6 is a diagram for explaining an operation of a detection unit 700a2 included in a horizontal recursive filter 700a in the recursive filter 72. FIG. It is a diagram showing a projector 1000 equipped with an image quality improvement apparatus 100A. FIG. 6 is a diagram showing a cyclic filter 701 applied to the cyclic filters 71 and 72. It is the figure which showed the vertical recursive filter 701b. 7 is a diagram for explaining the operation of a detection unit 701b2 included in a vertical cyclic filter 701b in the cyclic filter 71. FIG. 6 is a diagram for explaining the operation of a detection unit 701b2 included in a vertical recursive filter 701b in the recursive filter 72. FIG. FIG. 6 is a diagram showing a recursive filter 702. An example of a video signal representing an image in which a plurality of images are arranged in a horizontal direction (horizontal direction) and a vertical direction (vertical direction) of a multi-image, a reset signal in the horizontal recursive filter 700a, and a reset in the vertical recursive filter 701b It is the figure which showed the example with a signal.

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

(First embodiment)
FIG. 6 is a diagram showing an image quality improvement apparatus 100A according to the first embodiment of the present invention. The image quality improving apparatus 100A is mounted on an image display apparatus such as a projector or a monitor.

  In FIG. 6, the same components as those shown in FIG. The image quality improving apparatus 100A of the present embodiment is different from the image quality improving apparatus 100 shown in FIG. 1 in that it includes a two-dimensional LPF 7 instead of the two-dimensional LPF 1 shown in FIG. Hereinafter, the image quality improvement apparatus 100A of the present embodiment will be described focusing on differences from the image quality improvement apparatus 100 shown in FIG.

  In FIG. 6, the image quality improving apparatus 100 </ b> A includes delay compensation units 2 and 3, a subtracting unit 4, an amplifying unit 5, an adding unit 6, and a two-dimensional LPF 7.

  Hereinafter, a description will be given of a situation where a multi-image video signal representing a plurality of images is input to the image quality improvement apparatus 100A. Specifically, a video signal representing an image in which a plurality of images are arranged in the horizontal direction (lateral direction) of a multi-image is used as a video signal (input video signal) input to the image quality improvement apparatus 100A. The operation when a video signal representing one image is input to the image quality improving apparatus 100A is the same as that of the image quality improving apparatus 100 shown in FIG.

  FIG. 7 is a diagram showing a two-dimensional LPF 7.

  In FIG. 7, the two-dimensional LPF 7 includes recursive filters 71 and 72 and time axis inversion units 73 and 74.

  In the two-dimensional LPF 7, after the recursive filter 71 performs the two-dimensional low-pass filter processing on the input signal (video signal), the time axis inversion unit 73 inverts the input signal that has been subjected to the two-dimensional low-pass filter processing. Then, the recursive filter 72 further performs two-dimensional low-pass filter processing on the time-inverted signal, and then the time-axis reversing unit 74 further reverses the output of the recursive filter 72 with respect to the time axis.

  For this reason, after the time axis inversion by the time axis inversion unit 73, the recursive filter 72 has an order opposite to the order of the video signals (image data) supplied to the recursive filter 71 in both the horizontal and vertical directions. The video signal (image data) is input.

  For example, the recursive filter 71 receives image data one by one from the leftmost image data in the uppermost line of the image to the rightmost image data in the same line, and then the leftmost image in the next lower line. The input of image data one by one from the image data to the rightmost image data of the same line is repeated up to the bottom line of the image.

  On the other hand, the recursive filter 72 receives image data one by one from the right end image data in the bottom line of the image to the left end image data of the same line, and then the right end in the upper line. The input of image data one by one from the image data to the leftmost image data of the same line is repeated up to the top line of the image.

  For this reason, in the recursive filter 71, image quality correction is performed on the image from the left to the right in order to suppress degradation in image quality caused by flare in the horizontal direction, and in the vertical direction from top to bottom. Image quality correction is performed to suppress image quality degradation caused by flare. On the other hand, in the recursive filter 72, image quality correction is performed on the image from the right to the left in order to suppress deterioration in image quality caused by flare in the horizontal direction, and flare in the vertical direction from bottom to top. The image quality correction for suppressing the deterioration of the image quality due to the image quality is performed.

  Note that the time axis inversion processing performed by the time axis inversion units 73 and 74 is a known technique, and thus detailed description thereof is omitted.

  In the present embodiment, the recursive filter 71 and the recursive filter 72 have the same configuration.

  FIG. 8 is a diagram showing a recursive filter 700 applied to the recursive filters 71 and 72. In FIG. 8, the same components as those shown in FIG.

  In FIG. 8, the recursive filter 700 includes a horizontal recursive filter 700a and a vertical recursive filter 10b. In the example shown in FIG. 8, the output of the horizontal cyclic filter 700a is supplied to the vertical cyclic filter 10b. However, the output of the vertical cyclic filter 10b is supplied to the horizontal cyclic filter 700a. The order may be changed.

  FIG. 9 is a diagram showing a horizontal recursive filter 700a. In FIG. 9, the same components as those shown in FIG.

  Hereinafter, the horizontal recursive filter 700a will be described focusing on differences from the horizontal recursive filter 10a illustrated in FIG.

  In FIG. 9, the horizontal recursive filter 700a includes an amplifying unit 10a1, an adding unit 10a2, an amplifying unit 10a4, a feedback line 10a5, and a one-pixel period delay unit 700a1, and is connected to the detecting unit 700a2. Hereinafter, the detection unit 700a2 is also referred to as a detection unit 700a2 in the horizontal recursive filter 700a.

  The detection unit 700a2 includes a dot counter 700a21 and a comparison unit 700a22.

  The one-pixel period delay unit 700a1 is an example of a delay unit.

  The one-pixel period delay unit 700a1 is provided in a feedback line 10a5 that feeds back the output of the adder 10a2 to the other input of the adder 10a2.

  The one-pixel period delay unit 700a1 generates a delay signal by delaying the output of the addition unit 10a2 by one pixel period (one image data period), and outputs the delay signal.

  The one-pixel period delay unit 700a1 is reset when the output from the comparison unit 700a22 is “H”. Hereinafter, the output of “H” from the comparison unit 700a22 is also referred to as “reset signal R”. During normal operation, the “L” output from the comparison unit 700a22 is input to the one-pixel period delay unit 700a1. That is, the reset signal R is not output during normal operation.

  The horizontal recursive filter 700a is a weighted addition value of the image data represented by the input video signal for each pixel period within one horizontal period and the image data and the image data already input within the horizontal period. By doing so, a filtering process for removing a high frequency component (edge component) in the horizontal direction of the image represented by the video signal from the input video signal is performed.

  Further, while receiving the reset signal R (“H” output from the comparison unit 700a22), the one-pixel period delay unit 700a1 is reset and temporarily stops outputting the delay signal to set the output to “L”. . For this reason, while receiving the reset signal R, the horizontal recursive filter 700a does not function as a recursive filter, and the video signal input before receiving the reset signal R at the output of the horizontal recursive filter 700a thereafter. No effect.

  Thereafter, when the output from the comparison unit 700a22 becomes “L”, the horizontal recursive filter 700a functions as a recursive filter again from that time, and the high frequency component is removed from the video signal.

  Therefore, if the reset signal R is input to the one-pixel period delay unit 700a1 at the timing when the video signal represents the image data serving as the boundary between the plurality of images in the multi-image (hereinafter referred to as “boundary timing”), the multi-image Each image in the image can be subjected to image quality correction for suppressing deterioration in image quality due to flare without being affected by the adjacent image.

  The detection unit 700a2 functions as a control unit, and outputs a reset signal R (output of “H”) at the boundary timing.

  The dot counter 700a21 receives a horizontal data enable signal (hereinafter referred to as “horizontal DE signal”) and a dot clock.

  The horizontal DE signal is a signal representing a video period in the horizontal direction. For example, when the video signal input to the image quality improvement apparatus 100A represents a multi-image projection image in which two images are arranged side by side in the entire horizontal region of the display region, the horizontal DE signal is a horizontal signal in the projection image. The whole video period in the direction, that is, both periods of two images arranged on the left and right are expressed as effective display periods. Further, the horizontal DE signal represents an invalid display period other than the valid display period.

  On the other hand, the dot clock is a clock signal synchronized with each pixel (each image data).

  The dot counter 700a21 counts the number of dot clocks input during a period in which the horizontal DE signal represents the effective display period, and represents the number of pixels since the horizontal DE signal has entered the effective display period. Further, the dot counter 700a21 returns the count value to 0 when the horizontal DE signal enters the invalid display period. The count value of the dot counter 700a21 is output to the comparison unit 700a22.

  The comparison unit 700a22 compares the count value from the dot counter 700a21 with the image horizontal width represented by the image information.

  The image information may represent an image horizontal width and an image vertical width of each image, or may be information representing an image start position and an image end position in the horizontal direction and the vertical direction of each image.

  In the present embodiment, image horizontal width information representing the image horizontal width of each image in the multi-image is used as the image information.

  The image horizontal width information is supplied from, for example, a device (for example, an image processing unit in a projector) that has created a video signal representing a multi-image.

  Here, the horizontal recursive filter 700a in the recursive filter 71 and the horizontal recursive filter 700a in the recursive filter 72 connected via the time axis inversion unit 73 shown in FIG. Since the order of the image data represented by the video signal changes, the required image horizontal width also changes before and after the time axis inversion unit 73.

  In the horizontal recursive filter 700a in the recursive filter 71, the image horizontal width is the horizontal width (number of dots) of the left image among the images displayed side by side.

  On the other hand, in the horizontal recursive filter 700a in the recursive filter 72, the image horizontal width is the horizontal width (number of dots) of the right image among the images displayed side by side.

  That is, the horizontal width of the image used in the recursive filter is the horizontal width (number of dots) of the image input to the recursive filter first.

  The comparison unit 700a22 shown in FIG. 9 compares the count value from the dot counter 700a21 with the image horizontal width, and sets the output to “H” (that is, outputs the reset signal R) only when they match.

  FIG. 10 is a diagram for explaining the operation of the detection unit 700a2 (hereinafter referred to as “detection unit 700a2a”) included in the horizontal recursive filter 700a in the recursive filter 71.

  As shown in FIG. 10, in the detection unit 700a2a, the comparison unit 700a22 outputs the reset signal R when the count value of the dot counter 700a21 becomes a value mL corresponding to the image horizontal width L of the left image. In FIG. 10, the period defined by the image horizontal widths L and R is an example of a divided period obtained by dividing the horizontal period of the input image based on the horizontal period of the right image and the left image.

  FIG. 11 is a diagram for explaining the operation of detection unit 700a2 (hereinafter referred to as “detection unit 700a2b”) included in horizontal recursive filter 700a in recursive filter 72.

  Since the recursive filter 72 is in the subsequent stage of the time axis inversion unit 73, the image represented by the image signal input to the recursive filter 72 is the image represented by the image signal input to the recursive filter 71 in the vertical and horizontal directions. Are input in reverse.

  As shown in FIG. 11, in the detection unit 700a2b, the comparison unit 700a22 outputs a reset signal R when the count value of the dot counter 700a21 becomes a value mR corresponding to the image horizontal width R of the right image.

  For this reason, all the reset signals R from the comparison units 700a22 in the recursive filters 71 and 72 are output at the boundary between the images displayed side by side.

  As described above, by resetting the feedback signal of the horizontal recursive filter every time at the boundary between the images displayed side by side, the left and right images can be flare-free without being affected by adjacent images. Therefore, it is possible to perform image quality correction for suppressing deterioration in image quality due to the image quality, and to improve the image quality.

  In the above embodiment, the number of images in the multi-image is two, but the number of images in the multi-image may be more than two. In this case, resetting is performed at the timing of the boundary between the images.

  According to this embodiment, the two-dimensional LPF 7 extracts a low frequency component from the input video signal. The subtracting unit 4 subtracts the low frequency component extracted by the two-dimensional LPF 7 from the input video signal to obtain the high frequency component. The adding unit 6 performs image quality correction on the input video signal by adding the high frequency component acquired by the subtracting unit 4 to the input video signal. The two-dimensional LPF 7 includes a recursive filter 71.

  The recursive filter 71 performs a weighted addition process that weights and adds the input video signal and a delayed signal obtained by giving a delay of a predetermined time to the output of the cyclic filter 71, and the result of the weighted addition process is used as the input video signal. Output as the low frequency component of the signal.

  Then, when the input video signal is a multi-image video signal representing a plurality of images, the detection unit 700a2 uses the recursive filter 71 to perform a weighted addition process for each image in the multi-image.

  Therefore, when the input video signal is a multi-image video signal representing a plurality of images, the recursive filter 71 performs weighted addition processing for each image in the multi-image.

  For this reason, in a multi-image, filter processing (weighted addition processing) is performed on an image-by-image basis, and the image in the multi-image is affected by other images in the multi-image, and the image quality of the entire image in each image in the multi-image Can be suppressed.

  Further, in the present embodiment, the horizontal recursive filter 700a is configured such that, for a horizontal period of an input video signal representing a multi-image in which a plurality of images are arranged in the horizontal direction, the input video signal is a boundary between the plurality of images within the horizontal period. A weighted addition process is executed for each of a plurality of divided periods obtained by dividing the horizontal period with the boundary timing representing the image data as a base point, thereby extracting a low frequency component in the horizontal direction of the input video signal.

  For this reason, in a multi-image in which a plurality of images are arranged in the horizontal direction, it is possible to suppress a reduction in image quality due to the influence of other images in the multi-image.

  In the present embodiment, the feedback line 10a5 supplies the output of the horizontal recursive filter 700a to the adder 10a2. The 1-pixel delay unit 700a1 is provided in the feedback line 10a5, generates a delayed signal by giving a delay of 1 pixel time (predetermined time) to the output of the horizontal recursive filter 700a, and outputs the delayed signal. The adder 10a2 performs weighted addition of the input video signal and the delayed signal received through the feedback line 10a5, and outputs the result of the weighted addition as the output of the horizontal recursive filter 700a. Then, the 1-pixel delay unit 700a1 temporarily stops outputting the delay signal and sets the output to “L” at the boundary timing.

  For this reason, in the horizontal recursive filter 700a, the signal input to the adder 10a2 from the feedback line 10a5 temporarily stops at the boundary timing, and thereafter, before the boundary timing for the output (result of weighted addition) of the adder 10a2. The effect of the input video signal is eliminated. Therefore, it is possible to prevent the image in the multi-image from being deteriorated due to the influence of other images in the multi-image.

  In the present embodiment, the detection unit 700a2 detects the boundary timing based on the divided period representing each period of the plurality of images in the horizontal period and the number of image data received in the horizontal period. When the detection unit 700a2 detects the boundary timing, the 1-pixel delay unit 700a1 temporarily stops outputting the delay signal and sets the output to “L”.

  For this reason, the boundary timing can be automatically detected based on the divided period representing each period of the plurality of images in the horizontal period and the number of image data received in the horizontal period.

  FIG. 12 is a diagram showing a projector 1000 equipped with the image quality improvement apparatus 100A. In FIG. 12, the same components as those shown in FIG.

  In FIG. 12, the projector 1000 includes an image quality improvement device 100 </ b> A, an image processing unit 8, and a projection unit 9.

  The image processing unit 8 receives independent video signals from PCs (personal computers) 2000 and 3000. Note that the video signal supply source is not limited to the PC and can be changed as appropriate. Further, the number of video signal suppliers is not limited to two. For example, the image processing unit 8 receives one video signal and generates a new video signal (for example, a copy of the received video signal or a video signal obtained by delaying the received video signal) from the received video signal. The received video signal and new video signal may be used in place of the video signals from the PC 2000 and 3000. The image processing unit 8 and the detection unit 700a2 constitute a control unit.

  The image processing unit 8 uses each video signal from the PCs 2000 and 3000 to generate a video signal representing a multi-image in which images represented by the video signals are arranged in the horizontal direction (hereinafter referred to as “multi-image video signal”). .

  For example, the image processing unit 8 generates a multi-image video signal representing a multi-image in which the images represented by the video signals are arranged in the horizontal direction so that the horizontal widths of the images represented by the video signals are equal.

  Note that the horizontal width of each image in the multi-image may be set according to an instruction from the user, for example.

  Further, the image processing unit 8 generates image horizontal width information representing the image horizontal width of each image in the multi-image. The image processing unit 8 outputs the multi-image video signal and each image horizontal width information to the image quality improvement apparatus 100A.

  The image quality improvement apparatus 100A accepts a multi-image video signal as an input video signal, accepts each image horizontal width information, and performs image quality correction on the multi-image video signal to suppress degradation in image quality due to flare. Do. The image quality improving apparatus 100A outputs to the projection unit 9 a multi-image video signal that has been subjected to image quality correction for suppressing deterioration in image quality due to flare.

  The projection unit 9 is an example of a display unit. The projection unit 9 receives a multi-image video signal that has been subjected to image quality correction to suppress a reduction in image quality due to flare, and displays the multi-image represented by the multi-image video signal on a projection surface such as a screen (not shown). Projects and displays a multi-image on the projection surface.

  The projection unit 9, for example, a liquid crystal panel that forms a multi-image represented by a multi-image video signal that has been subjected to image quality correction for suppressing deterioration in image quality due to flare, and illuminates the liquid crystal panel to generate a multi-image. A light source that generates a projection image; and a projection optical system that forms an image of the projection image generated by the light source on a projection surface.

  For this reason, it is possible to suppress the deterioration of the image quality of the multi-image displayed on the projection surface by the projector 1000.

  In place of the liquid crystal panel, a DMD (Digital Micromirror Device) or another display element may be used.

  The image quality improving apparatus 100A may be mounted on a monitor having a display unit. In this case, a display unit (for example, a liquid crystal panel, a plasma panel, or an organic EL (Electro Luminescence) panel) is used instead of the projection unit 9 in FIG.

(Second Embodiment)
In the first embodiment, a video signal representing an image in which a plurality of images are arranged in the horizontal direction (lateral direction) of the multi-image is used as the video signal input to the image quality improvement apparatus.

  On the other hand, in the second embodiment, a video signal representing an image in which a plurality of images are arranged in the vertical direction (vertical direction) of a multi-image is used as a video signal input to the image quality improvement apparatus.

  The difference between the image quality improvement apparatus according to the second embodiment and the image quality improvement apparatus according to the first embodiment is that the image quality improvement apparatus according to the second embodiment uses the cyclic filters 71 and 72 shown in FIG. The type filter is different from the cyclic filter (cyclic filter 700 shown in FIG. 8) used in the first embodiment.

  Hereinafter, the image quality improvement apparatus according to the second embodiment will be described focusing on differences from the image quality improvement apparatus according to the first embodiment.

  FIG. 13 is a diagram showing a cyclic filter 701 applied to the cyclic filters 71 and 72 shown in FIG. In FIG. 13, the same components as those shown in FIG.

  In FIG. 13, a recursive filter 701 includes a horizontal recursive filter 10a and a vertical recursive filter 701b. In the example shown in FIG. 13, the output of the horizontal cyclic filter 10a is supplied to the vertical cyclic filter 701b. However, the output of the vertical cyclic filter 701b is supplied to the horizontal cyclic filter 10a. The order may be changed.

  FIG. 14 is a diagram showing the vertical recursive filter 701b. In FIG. 14, the same components as those shown in FIG.

  Hereinafter, the vertical recursive filter 701b will be described focusing on differences from the vertical recursive filter 10b shown in FIG.

  In FIG. 14, a vertical recursive filter 701b includes an amplifying unit 10b1, an adding unit 10b2, an amplifying unit 10b4, a feedback line 10b5, and a one horizontal period delay unit 701b1, and is connected to the detecting unit 701b2. Hereinafter, the detection unit 701b2 is also referred to as a detection unit 701b2 in the vertical recursive filter 701b.

  The detection unit 701b2 includes a line counter 701b21 and a comparison unit 701b22.

  The one horizontal period delay unit 701b1 is an example of a delay unit.

  The one horizontal period delay unit 701b1 is provided in the feedback line 10b5 that feeds back the output of the adder 10b2 to the other input of the adder 10b2.

  The one horizontal period delay unit 701b1 generates a delay signal by delaying the output of the addition unit 10b2 by one horizontal period, and outputs the delay signal.

  The one horizontal period delay unit 701b1 is reset when the output from the comparison unit 701b22 is “H”. Hereinafter, the output of “H” from the comparison unit 700a22 is also referred to as “reset signal R1”. During normal operation, the “L” output from the comparison unit 701b22 is input to the one horizontal period delay unit 701b1. That is, the reset signal R1 is not output during normal operation.

  The vertical recursive filter 701b displays image data represented by a video signal for each pixel period in one vertical period, the image data, and a multiple of the horizontal period from the input timing of the image data in the one vertical period. Filter processing that removes a high frequency component (edge component) in the vertical direction of the video represented by the video signal from the video signal by using a weighted addition value of the image data that has already been input before a certain period. Do.

  Further, while receiving the reset signal R1 (“H” output from the comparison unit 701b22), the one horizontal period delay unit 701b1 temporarily resets the output of the delay signal and sets the output to “L” while receiving the reset signal R1 (“H” output from the comparison unit 701b22). . For this reason, while receiving the reset signal R1, the vertical recursive filter 701b does not function as a recursive filter, and the video signal input before receiving the reset signal R1 at the output of the subsequent vertical recursive filter 701b. No effect.

  Thereafter, when the output from the comparison unit 701b22 becomes “L”, the vertical recursive filter 701b functions as a recursive filter again from that time, and a high frequency component is removed from the video signal.

  Therefore, if the reset signal R1 is input to the one horizontal period delay unit 701b1 at the timing (boundary timing) when the video signal represents the image data that is the boundary between the plurality of images in the multi-image, each image in the multi-image is displayed. Can be subjected to image quality correction for suppressing deterioration of image quality due to flare without being influenced by adjacent images.

  The detection unit 701b2 functions as a control unit, and outputs a reset signal R1 (output of “H”) at the boundary timing.

  The line counter 701 b 21 receives a vertical data enable signal (hereinafter referred to as “vertical DE signal”) and a horizontal synchronization signal.

  The vertical DE signal is a signal representing a video period in the vertical direction. For example, when the input video signal represents a multi-image projection image in which two images are arranged vertically in the entire vertical region of the display region, the vertical DE signal represents the entire vertical video period in the projection image. That is, both periods of two images arranged vertically are expressed as effective display periods. The vertical DE signal represents an invalid display period other than the valid display period.

  On the other hand, the horizontal synchronization signal is a signal synchronized with each line.

  The line counter 701b21 counts the number of horizontal synchronization signals input during a period in which the vertical DE signal represents the effective display period, and represents the number of lines since the vertical DE signal has entered the effective display period. The line counter 701b21 returns the count value to 0 when the vertical DE signal enters the invalid display period. The count value of the line counter 701b21 is output to the comparison unit 701b22.

  The comparison unit 701b22 compares the count value from the line counter 701b21 with the image vertical width (number of image vertical lines) represented by the image information.

  The image information may represent the image horizontal width and the image vertical width of each image, as described in the first embodiment, and represents the image start position and image end position of each image in the horizontal direction and the vertical direction. It may be information.

  In the present embodiment, image vertical line number information representing the image vertical width of each image in the multi-image is used as the image information.

  The image vertical line number information is supplied from, for example, a device (for example, an image processing unit in a projector) that has created a video signal representing a multi-image.

  Here, the signals are input to the vertical recursive filter 701 b in the recursive filter 71 and the vertical recursive filter 701 b in the recursive filter 72 connected via the time axis inversion unit 73 shown in FIG. Since the order of the image data represented by the video signal changes, the number of required image vertical lines also changes before and after the time axis inversion unit 73.

  In the vertical recursive filter 701b in the recursive filter 71, the number of image vertical lines of the upper image among the images displayed side by side is used as the number of image vertical lines.

  On the other hand, in the vertical recursive filter 701b in the recursive filter 72, the number of image vertical lines of the lower image among the images displayed side by side is used as the number of image vertical lines.

  That is, the number of image vertical lines used in the recursive filter is the vertical width (the number of vertical lines) of the image previously input to the recursive filter.

  The comparison unit 701b22 shown in FIG. 14 compares the count value from the line counter 701b21 with the number of image vertical lines, and sets the output to “H” (that is, outputs the reset signal R1) only when they match. . The width of the reset signal R1 is one line. It should be noted that the width of one line may include a period during which the video signal is valid.

  FIG. 15 is a diagram for explaining the operation of the detection unit 701b2 (hereinafter referred to as “detection unit 701b2a”) included in the vertical cyclic filter 701b in the cyclic filter 71.

  As shown in FIG. 15, in the detection unit 701b2a, the comparison unit 701b22 outputs the reset signal R1 when the count value of the line counter 701b21 becomes a value nU corresponding to the number of image lines (image vertical width) U of the upper image. To do. In FIG. 15, the period defined by the image vertical widths U and D is an example of a divided period obtained by dividing the vertical period of the input image based on the vertical period of each image.

  FIG. 16 is a diagram for explaining the operation of the detection unit 701b2 (hereinafter referred to as “detection unit 701b2b”) included in the vertical cyclic filter 701b in the cyclic filter 72.

  Since the recursive filter 72 is in the subsequent stage of the time axis inversion unit 73, the image represented by the image signal input to the recursive filter 72 is the image represented by the image signal input to the recursive filter 71 in the vertical and horizontal directions. Are input in reverse.

  As shown in FIG. 16, in the detection unit 701b2b, the comparison unit 701b22 outputs the reset signal R1 when the count value of the line counter 701b21 becomes a value nD corresponding to the number of image lines (image vertical width) D of the lower image. Output.

  For this reason, all the reset signals R1 from the comparison units 701b22 in the recursive filters 71 and 72 are output at the boundary between images displayed side by side.

  As described above, the feedback signal of the vertical recursive filter is reset each time at the boundary between the images displayed side by side, so that the flare is not affected by the adjacent images in the upper and lower images. Therefore, it is possible to perform image quality correction for suppressing deterioration in image quality due to the image quality, and to improve the image quality.

  In each of the above embodiments, the two images (input images) corresponding to the input video signal are arranged in contact with each other in the multi-screen. However, the two images may be arranged apart from each other.

  At this time, separated images that clarify the respective regions of the plurality of input images may be displayed on the upper side, the lower side, the right side, the left side, or between the images. The separated image is displayed as an image indicating the boundary between the images, for example, black or blue. The separated image may be an illustration or a natural image.

  In this case, the reset is performed at a timing according to the start position and end position of the image, which is the timing of each image boundary, or at a timing according to the entire period for displaying the separated image.

  When the separated image is displayed in black, the reset may be performed only at the timing corresponding to the start position that is the timing of the boundary between images scanned next to the separated image. This is because resetting at this position eliminates the influence of the separation image on the input image, while the separation image is not affected by the input image because the video level of the separation image is the black level. In other words, since the separated image is black, there is no video signal level below black even if image quality correction is applied to suppress the degradation in image quality caused by flare, so the black video signal is not actually corrected. Because. Further, the image arranged in the multi-image is not limited to the input image, and may be an image (generated image) generated inside the apparatus.

(Third embodiment)
In the third embodiment, a video signal representing an image in which a plurality of images are arranged in the horizontal direction (horizontal direction) and the vertical direction (vertical direction) of a multi-image is used as a video signal input to the image quality improvement apparatus.

  The difference between the image quality improvement apparatus of the third embodiment and the image quality improvement apparatuses of the first and second embodiments is that the image quality improvement apparatus of the third embodiment is applied to the cyclic filters 71 and 72 shown in FIG. The cyclic filter used is different from the cyclic filters used in the first and second embodiments (the cyclic filter 700 shown in FIG. 8 and the cyclic filter 701 shown in FIG. 13).

  Hereinafter, the image quality improvement apparatus according to the third embodiment will be described focusing on differences from the image quality improvement apparatuses according to the first and second embodiments.

  FIG. 17 is a diagram showing a cyclic filter 702 applied to the cyclic filters 71 and 72 shown in FIG. In FIG. 17, the same components as those shown in FIGS. 8, 9, 13, and 14 are denoted by the same reference numerals.

  In FIG. 17, a recursive filter 702 includes a horizontal recursive filter 700a used in the first embodiment and a vertical recursive filter 701b used in the second embodiment. In the example shown in FIG. 17, the output of the horizontal cyclic filter 700a is supplied to the vertical cyclic filter 701b, but the output of the vertical cyclic filter 701b is supplied to the horizontal cyclic filter 700a. The order may be changed.

  FIG. 18 shows an example of a video signal representing an image in which a plurality of images are arranged in the horizontal direction (horizontal direction) and the vertical direction (vertical direction) of a multi-image, and a reset signal (“H” of the horizontal recursive filter 700a). FIG. 6 is a diagram illustrating an example of a signal) and a reset signal (“H” signal) in the vertical recursive filter 701b.

  In the present embodiment, the period of the image including the images I1, I2, and I3 is represented as an effective display period. The horizontal and vertical start and end positions of the images I1, I2, and I3 are image information (boundary position information) from an image composition unit and an image processing unit that synthesize images including the images I1, I2, and I3. Is entered as Note that the image composition unit and the image processing unit are devices in front of the image quality improvement apparatus.

  In the present embodiment, one of three types of reset signals is output according to the image information.

  The resets RH11, RH21, and RV1 are applied when the area between the images is black, and are “H” signals. When the area between the images is black, the image quality correction to suppress the deterioration of image quality caused by flare is to correct the black level to a value lower than the black level, but a value lower than the black level. Because there is no, it is clipped to the black level.

  The resets RH12, RH22, and RV2 are “H” signals, and are reset in accordance with the boundary position between the start position and the end position of the image.

  The resets RH13, RH23, and RV3 are “H” signals, and are reset in accordance with the width of the area between the images.

  In the present embodiment, the image vertical line number information and the image horizontal width information that determine the reset timing are changed according to the input image data (the order of the image data in the video signal).

  For example, when the reset RH12 for the image I1 is output, in a situation immediately before the leftmost image data of the image I1 is input, the comparison unit 700a22 indicates “m1” indicating the start position of the image I1 as the image horizontal width information. Is input, and “m2” representing the end position of the image I1 is input as the image horizontal width information to the comparison unit 700a22.

  In the present embodiment, the method of performing the image quality correction for reversing the time axis and suppressing the deterioration of the image quality caused by flare is the same as that of the first embodiment in the horizontal direction, and the first method in the vertical direction. This is the same as in the second embodiment.

  In each embodiment described above, the illustrated configuration is merely an example, and the present invention is not limited to the configuration.

100A Image quality improvement device
2, 3 Delay compensator
4 Subtraction part
5 Amplification part
6 Adder
7 2D LPF
71, 72, 700 Recursive filter
73, 74 Time axis reversal part
700a Horizontal recursive filter
700a1 1 pixel delay unit
700a2 detector
700a21 dot counter
700a22 comparison part
701 Recursive filter
701b Vertical cyclic filter
701b1 1 horizontal period delay unit
701b2 detector
701b21 line counter
701b22 comparison unit
702 Recursive filter
8 Image processing unit
9 Projection unit 10a1, 10a4 Amplification unit 10a2 Addition unit 10a5 Feedback line 10b Vertical cyclic filter 1000 Projector 2000, 3000 PC

Claims (6)

A low pass filter that extracts low frequency components from the input video signal;
A subtracting unit for subtracting a low frequency component extracted by the low pass filter from the input video signal to obtain a high frequency component;
An addition unit that performs image quality correction on the input video signal by adding the high-frequency component obtained by the subtraction unit to the input video signal;
The low-pass filter performs a weighted addition process for weighted addition of the input video signal and a delayed signal obtained by giving a delay of a predetermined time to its output, and uses the result of the weighted addition process as the low frequency component Including a recursive filter to output,
The weighted addition process using the cyclic filter is performed on the image represented by the input video signal, and the weighted addition process using the cyclic filter is performed when the input video signal represents a plurality of images. Including a control unit that executes each of the plurality of images,
The input video signal represents a composite image in which the plurality of images are arranged in the horizontal direction of the image, and for each of a plurality of lines constituting the composite image, the image data in the line is sequentially represented,
The predetermined time is one image data period;
The control unit detects, for a horizontal period that is a display period of each of the plurality of lines, a boundary timing representing image data in which the input video signal is a boundary of the plurality of images within the horizontal period, For each of a plurality of divided periods obtained by dividing the horizontal period based on a boundary timing, a low frequency component in the horizontal direction of an image represented by the input video signal by executing the weighted addition process using the cyclic filter Extract
The image quality improvement apparatus, wherein the control unit detects the boundary timing based on the division period and the number of image data received in the horizontal period. The image quality improving apparatus according to claim 1,
The recursive filter is
A feedback line that feeds back the output of the cyclic filter to the cyclic filter;
A delay unit that is provided in the feedback line, generates a delay signal by giving a delay of the predetermined time to the output of the cyclic filter, and outputs the delay signal;
An adder that performs weighted addition of the input video signal and the delayed signal received through the feedback line, and outputs a result of the weighted addition as an output of the cyclic filter;
The image quality improvement apparatus, wherein the control unit temporarily stops outputting a delay signal from the delay unit at the boundary timing. A low pass filter that extracts low frequency components from the input video signal;
A subtracting unit for subtracting a low frequency component extracted by the low pass filter from the input video signal to obtain a high frequency component;
An addition unit that performs image quality correction on the input video signal by adding the high-frequency component obtained by the subtraction unit to the input video signal;
The low-pass filter performs a weighted addition process that weights and adds the input video signal and a delayed signal obtained by giving a delay of a predetermined time to its own output, and outputs the result of the weighted addition process as the low frequency component Including a recursive filter that
The weighted addition process using the cyclic filter is performed on the image represented by the input video signal, and the weighted addition process using the cyclic filter is performed when the input video signal represents a plurality of images. Including a control unit that executes each of the plurality of images,
The input video signal represents a composite image in which the plurality of images are arranged in the vertical direction of the image, and sequentially represents the image data in the line for each of the plurality of lines constituting the composite image,
The predetermined time is one horizontal period;
The recursive filter is
A feedback line that feeds back the output of the cyclic filter to the cyclic filter;
A delay unit that is provided in the feedback line, generates a delay signal by giving a delay of the predetermined time to the output of the cyclic filter, and outputs the delay signal;
An adder that performs weighted addition of the input video signal and the delayed signal received through the feedback line, and outputs a result of the weighted addition as an output of the cyclic filter;
The control unit detects, for a vertical period that is a display period of the composite image, a boundary timing that represents image data in which the input video signal serves as a boundary between the plurality of images within the vertical period, and at the boundary timing An image quality improving apparatus for temporarily stopping output of a delay signal from the delay unit. An image quality improving apparatus according to any one of claims 1 to 3,
An image display device including a display unit for displaying an image in accordance with an input video signal in which the image quality correction has been performed by the image quality improving apparatus. An image quality improvement method performed by an image quality improvement device,
Extract low frequency components from the input video signal,
Subtracting the low frequency component from the input video signal to obtain a high frequency component,
By adding the high frequency component to the input video signal, image quality correction is performed on the input video signal,
The low frequency component is extracted by performing a weighted addition process that weights and adds the input video signal and a delayed signal obtained by delaying the output of the input video signal by a predetermined time. Output as a frequency component,
When the input video signal represents a plurality of images, the weighted addition process is executed for each of the plurality of images. When the input video signal represents a plurality of images, the weighted addition process is performed. Run for each image,
The input video signal represents a composite image in which the plurality of images are arranged in a horizontal direction of the images,
For each of a plurality of lines constituting the composite image, the image data in the lines are represented in order,
The predetermined time is one image data period;
With respect to a horizontal period that is a display period of each of the plurality of lines, the input video signal detects a boundary timing representing image data that is a boundary of the plurality of images within the horizontal period, and the boundary timing is used as a base point. For each of a plurality of divided periods obtained by dividing the horizontal period, the weighted addition process is performed to extract a low frequency component in the horizontal direction of the image represented by the input video signal,
An image quality improvement method for detecting the boundary timing based on the divided period and the number of image data received in the horizontal period. An image quality improvement method performed by an image quality improvement device,
Extract low frequency components from the input video signal,
Subtracting the low frequency component from the input video signal to obtain a high frequency component,
By adding the high frequency component to the input video signal, image quality correction is performed on the input video signal,
The low frequency component is extracted by performing a weighted addition process that weights and adds the input video signal and a delayed signal obtained by delaying the output of the input video signal by a predetermined time. Output as a frequency component,
Performing the weighted addition process on the image represented by the input video signal, and when the input video signal represents a plurality of images, performing the weighted addition process for each of the plurality of images;
The input video signal represents a composite image in which the plurality of images are arranged in a vertical direction of the images,
For each of a plurality of lines constituting the composite image, the image data in the lines are represented in order,
The predetermined time is one horizontal period,
For a vertical period that is a display period of the composite image, a boundary timing in which the input video signal represents image data that is a boundary of the plurality of images within the vertical period is detected, and the delay signal is detected at the boundary timing. An image quality improvement method that temporarily stops output.

Images