WO2019123632A1

WO2019123632A1 - Video processing device, video display device, and video processing method

Info

Publication number: WO2019123632A1
Application number: PCT/JP2017/046136
Authority: WO
Inventors: 孝平賀
Original assignee: Ｎｅｃディスプレイソリューションズ株式会社
Priority date: 2017-12-22
Filing date: 2017-12-22
Publication date: 2019-06-27

Abstract

The present invention improves the ease of discrimination of grayscale values in both a dark region and a bright region while maintaining the ease of discrimination of grayscale values in an intermediate region. The video processing device (10) has: a first correction unit (11) for outputting a first video signal (S2) to which first correction has been applied so that a dark side of an image exhibits a larger degree of grayscale variation than the grayscale variation of an input video signal (S1) and a bright side of the image exhibits a smaller degree of grayscale variation than the grayscale variation of the input video signal (S1); a second correction unit (12) for outputting a second video signal (S3) to which second correction has been applied so that the dark side of the image exhibits a smaller degree of grayscale variation than the grayscale variation of the input video signal (S1) and the bright side of the image exhibits a larger degree of grayscale variation than the grayscale variation of the input video signal (S1); a signal switching unit (13) for selectively outputting one of the first and second video signals; and a control unit (14) for causing the image based on the first video signal and the image based on the second video signal to be alternatingly selected, in the signal switching unit, with respect to a prescribed number of pixels.

Description

Video processing apparatus, video display apparatus and video processing method

The present invention relates to a video processing device, a video display device, and a video processing method.

Generally, in an image display device such as a liquid crystal display or a projector, a dynamic range indicating a range in which the brightness can be determined from the darkest portion to the brightest portion is narrower than sensors of human eyes and cameras, etc. . For this reason, when a video signal with a large difference in brightness and darkness is displayed at each part in the display screen, it is difficult to distinguish between the dark part and the bright part, or both of the gradations, and all gradations of the original image are appropriately determined. It is difficult to express.

FIG. 8 shows an example of a display screen in which the gray scale of the bright part and the dark part is crushed. In FIG. 8, the upper part shows the video gradation characteristic, and the lower part shows the gray scale of the display screen according to the video gradation characteristic. In the video tone characteristics, the vertical axis represents the output tone of the display device, and the horizontal axis represents the tone of the original video. In this example, neither gamma correction nor inverse gamma correction is performed, and linear tone characteristics are shown. The gray scale is a change in brightness (brightness) according to the image tone characteristic shown in the upper part, which is expressed in 10 steps of the gray level (1) to (10). The lightness is lower on the gradation (1) side and higher on the gradation (10) side.
As shown in FIG. 8, it is difficult to distinguish between the gradation (1) and the gradation (2) in the dark part (the collapse of the dark part), and the discrimination between the gradation (9) and the gradation (10) in the bright part. Is also difficult (the collapse of the bright part). Gamma correction and inverse gamma correction are performed in order to improve the collapse of such dark and bright areas.

Gamma correction and inverse gamma correction mean adjusting the relative relationship between the change in brightness of the display screen and the change in brightness of the original image. Correcting the gradation of an image according to a curve of appropriate gamma values so as to make the dark part float is called gamma correction. The gradation characteristic used for this gamma correction is given by a curve whose inclination gradually decreases from the dark part to the light part. On the other hand, correcting the gradation of the image according to a curve of appropriate gamma values so as to sink the bright part is called inverse gamma correction. The gradation characteristic used for this inverse gamma correction is given by a curve whose slope gradually increases from the dark part to the light part.

FIG. 9 shows an example of a display screen when gamma correction is performed. Similar to FIG. 8, the upper part shows the video gradation characteristic, and the lower part shows the gray scale of the display screen according to the video gradation characteristic. By performing gamma correction according to the video tone characteristics of the curve (correction 1) and floating the dark portion, the tone characteristic of the dark portion is improved.
However, in the example of FIG. 9, although the brightness of the gradation (1) and the gradation (2) is discriminated, since the gradation of the bright part from the middle part is compressed, whiteout occurs. Therefore, it is difficult to distinguish between the gradation (8) and the gradation (9) and it is difficult to distinguish between the gradation (9) and the gradation (10).

FIG. 10 shows an example of a display screen when inverse gamma correction is performed. Similar to FIG. 8, the upper part shows the video gradation characteristic, and the lower part shows the gray scale of the display screen according to the video gradation characteristic. Inverse gamma correction is performed according to the image tone characteristics of the curve (correction 2) to sink the light portion, whereby the tone characteristic of the light portion is improved.
However, in the example of FIG. 10, although the brightness of the gradation (9) and the gradation (10) is discriminated, since the gradation of the dark part is compressed from the middle part, the darkening occurs. Therefore, it is difficult to distinguish between the gradation (3) and the gradation (2) and not distinguish between the gradation (2) and the gradation (1). In addition, the brightness of the bright part is reduced, such as gradation (10).

FIG. 11 shows an example of a display screen when gamma correction and inverse gamma correction are performed. Similar to FIG. 8, the upper part shows the video gradation characteristic, and the lower part shows the gray scale of the display screen. An image gradation characteristic of a curve (correction 3) in which the dark part is floated and the light part is sunk is obtained. By making the dark part float by gamma correction and sinking the bright part by inverse gamma correction, the tonality of the dark part and the bright part is improved.
However, in the example of FIG. 11, although the gray level (1) and the gray level (2) in the dark area, the gray level (9) and the gray level (10) in the bright area can be discriminated, Because the tonality is compressed, it is difficult to distinguish between the gradation (3) and the gradation (4), the gradation (7) and the gradation (8), and the brightness of each. I can't tell until (7). In addition, the brightness of the bright part is reduced, such as gradation (10).

In order to solve the problems described above with reference to FIGS. 8 to 11, it is necessary to increase the number of bits of the signal to be processed by the video signal processing circuit and to increase the gradation resolution. It is necessary to improve the performance, to decrease the brightness of black and to increase the brightness of white.

As a related art of gamma correction and inverse gamma correction, Patent Document 1 describes a method of changing a gamma correction characteristic to be applied to a pixel of interest based on the average luminance level of the pixel of interest and peripheral pixels. In this method, a correction characteristic is used in which the gamma value is increased as the average luminance level is higher. This lowers the positive gamma correction level.
Patent Document 2 describes a method of sequentially changing a gamma correction characteristic, continuously recording a plurality of still images, and combining an optimum background and a main subject among a plurality of images recorded.

In Patent Document 3, the average luminance level of the video signal is detected, the detected average luminance level is corrected so that the switching of the gamma correction characteristic is stabilized, and the gamma correction characteristic is switched according to the corrected average luminance level. A gamma correction circuit is described which corrects the video signal. For example, when the average luminance level is low, the gamma correction characteristic in which the dark part is floated is used, and when the average luminance level is high, the gamma correction characteristic in which the light part is floating is used.
Patent Document 4 describes a video display processing method of detecting a histogram of video signal levels and converting an input / output characteristic (gamma correction characteristic) based on an average value or variance of the histogram.

Japanese Patent Application Laid-Open No. 2010-119035 Japanese Patent Application Laid-Open No. 5-30456 Japanese Patent Application Laid-Open No. 7-38779 Japanese Patent Application Laid-Open No. 7-281633

In order to solve the problems described with reference to FIGS. 8 to 11, there are methods of increasing the number of bits of the signal processed by the video signal processing circuit and improving the optical performance of the display screen. In this case, the cost and size of the image display apparatus increase.

In the method described in Patent Document 1, when the average luminance level is high, the effect of the gradation expansion of the bright part is low only by reducing the positive gamma correction level. In addition, when correction (inverse gamma correction) using a correction characteristic with a small gamma value is performed, the brightness of the bright portion is reduced.
In the method described in Patent Document 2, in the correction to the bright part, the effect of the tone expansion of the bright part is low and the brightness of the bright part is also reduced by only reducing the positive gamma correction level.

In the gamma correction circuit described in Patent Document 3, when the average luminance level is high, the effect of the tone expansion of the bright part is low and the brightness of the bright part is also reduced only by lowering the positive gamma correction level. In addition, when light and dark areas exist on the screen, it is not possible to simultaneously increase the gradation of both the light and dark areas.
According to the method described in Patent Document 4, when the distribution of the bright part is large in the histogram of the video signal level, the effect of the gradation expansion of the bright part is low and the brightness of the bright part is low only by decreasing the positive gamma correction level. descend. When light and dark areas exist on the screen, it is not possible to simultaneously increase the gradation of both the light and dark areas.

An object of the present invention is to provide a video processing device, a video display device, and a video processing method that can solve the above problems.

In order to achieve the above object, according to the video processing device of the present invention, the amount of change in gradation of the first range on the side where the luminance of the gradation characteristic indicating the gradation of the image is lower than the input video signal is The amount of change in gradation of the second range, which is larger than the amount of change in gradation of the first range of the input video signal and on which the luminance of the gradation characteristic is high, corresponds to that of the input video signal. A first correction unit for outputting a first video signal subjected to the first correction so as to be smaller than a gradation change amount of the second range; The amount of change in gradation in the range of 1 is smaller than the amount of change in gradation in the first range of the input video signal, and the change amount of gradation in the second range is the input video signal Outputting the second video signal subjected to the second correction so as to be larger than the change amount of the gradation in the second range of A correction unit, a signal switching unit that receives the first and second video signals and selectively outputs one of the inputs, and a control unit that controls an input selection operation of the signal switching unit. And. The control unit causes the signal switching unit to alternately select an image based on the first video signal and an image based on the second video signal for each predetermined number of pixels.

Further, a video display device according to the present invention includes the video processing device, and a display unit for displaying an image based on an output video signal of the video processing device.

Further, according to the video processing method of the present invention, the amount of change in gradation of the first range on the side where the luminance of the gradation characteristic indicating the gradation of the image is lower than that of the input video signal is The change amount of the second range of gradations which is larger than the change amount of the first range of gradations and on which the luminance of the gradation characteristic is high is the second range of the input video signal. The first video signal subjected to the first correction is generated so as to be smaller than the gray level change amount, and the gray level change amount of the first range with respect to the input video signal is The change amount of the gradation of the second range which is smaller than the change amount of the gradation of the first range of the input video signal is the change of the gradation of the second range of the input video signal Generating a second video signal subjected to the second correction so as to be larger than the amount, and generating an image based on the first video signal And outputting alternately the image based on the second video signal every predetermined number of pixels.

FIG. 1 is a block diagram showing the configuration of a video processing apparatus according to a first embodiment of the present invention. It is a block diagram which shows the structure of the video processing apparatus of the 2nd Embodiment of this invention. It is a schematic diagram for demonstrating the video processing performed with the video processing apparatus shown in FIG. It is a figure for demonstrating the gradation characteristic of the video processing performed with the video processing apparatus shown in FIG. It is a schematic diagram for demonstrating the video processing performed with the video processing apparatus of the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the video display apparatus which is the 4th Embodiment of this invention. FIG. 6 is a characteristic diagram showing an example of an image gradation characteristic used in gamma correction and inverse gamma correction that can be applied to the image processing apparatus of the present invention. It is a figure for demonstrating the gradation characteristic of the display screen of a video processing apparatus. It is a figure for demonstrating the gradation characteristic at the time of performing a gamma correction. It is a figure for demonstrating the gradation characteristic at the time of performing a reverse gamma correction. It is a figure for demonstrating the gradation characteristic at the time of performing both gamma correction and reverse gamma correction.

Next, embodiments of the present invention will be described with reference to the drawings.
First Embodiment
FIG. 1 is a block diagram showing the configuration of a video processing apparatus according to the first embodiment of the present invention.
Referring to FIG. 1, the video processing apparatus 10 includes a first correction unit 11, a second correction unit 12, a signal switching unit 13, and a control unit 14.

In the first correction unit 11, the amount of change in gradation of the first range on the side where the luminance of the gradation characteristic indicating the gradation of the image is low (the side on which the image is dark) is The amount of change in gradation in the second range, which is larger than the amount of change in gradation in the first range of the input video signal S1 and on which the luminance of the gradation characteristics is high (the side on which the image is bright), is input. The first video signal S2 subjected to the first correction is output so as to be smaller than the change amount of the gradation of the second range of the video signal S1.
The first range is, for example, a range from 0% to 10% when the maximum value (brightest value) of the gray level of the image corresponding to the input video signal S1 is 100%. Also, the first range may be, for example, in the range of 0% to 20%. The second range is, for example, a range from 90% to 100% of gradation. The second range may be, for example, 80% to 100%.
The first correction is, for example, gamma correction. In gamma correction, the gradation of an image is corrected according to a curve of appropriate gamma values so as to float the dark part. In this case, for example, the gradation characteristic used for the gamma correction may be given by a curve whose inclination gradually decreases from the dark portion to the light portion.
The second correction unit 12 makes the amount of change in gradation of the first range smaller than the amount of change of gradation of the first range of the input video signal S1 with respect to the input video signal S1, and The second video signal S3 subjected to the second correction is output such that the amount of change in gradation in the range 2 is larger than the amount of change in gradation in the second range of the input video signal S1.
The second correction is, for example, inverse gamma correction. In inverse gamma correction, the gradation of the image is corrected according to a curve of appropriate gamma values so as to sink the bright part. In this case, for example, the gradation characteristic used for the inverse gamma correction may be given by a curve whose inclination gradually increases from the dark portion to the light portion.

The signal switching unit 13 receives the first video signal S2 and the second video signal S3 as inputs, and selectively outputs one of these inputs.
The control unit 14 outputs the image based on the first video signal S2 and the image based on the second video signal S3 alternately from the signal switching unit 13 every predetermined number of pictures (for example, every one pixel). Then, the correction operation of the first correction unit 11 and the second correction unit 12 and the input selection operation of the signal switching unit 13 are controlled. Here, the image based on the first video signal S2 and the image based on the second video signal S3 are images obtained from the same frame image (or the same field image) of the input video signal S1.

According to the image processing apparatus 10 of the present embodiment, an image in which the dark part is floated by the first correction (gamma correction) and an image in which the bright part is sunk by the second correction (inverse gamma correction) are displayed on the display screen. And can be alternately arranged and displayed for every predetermined number of strokes (for example, every one pixel). When the video pixel of the original image indicated by the input video signal S1 is the video signal level of the dark part, the first correction (gamma correction) is used to increase the brightness of the black level to improve the gradation discrimination. Can. When the video pixel is at the video signal level of the bright part, the second discrimination (reverse gamma correction) can be used to lower the brightness of white to improve the tone discrimination. In addition, the brightness of the image after gamma correction and the image after inverse gamma correction on the display screen due to the characteristics of the human eye (temporal or spatial resolution and afterimage phenomena related to space, time and brightness etc.) Is integrated, and an image obtained by combining both images is perceived. As a result, it is possible to improve the tone discrimination between the dark part and the light part while maintaining the tone discrimination of the middle part.

Further, according to the video processing apparatus 10 of the present embodiment, since it is not necessary to increase the number of bits of the video signal or to improve the optical performance of the display screen, neither cost increase nor size increase is caused.
In the video processing apparatus 10 according to the present embodiment, if the predetermined number of pixels can improve the tone discrimination between the dark part and the bright part while maintaining the tone discrimination of the middle part, Any value may be used.

Further, on the display screen for displaying an image based on the output video signal S4 of the signal switching unit 13, the control unit 14 displays an image based on the first video signal S2 and an image based on the second video signal S3 for each pixel. The input selection operation of the signal switching unit 13 may be controlled so as to be alternately displayed.
Furthermore, the control unit 14 sets a combination pixel formed by a plurality of pixels on the display screen as a display pixel unit, associates each combination pixel with each pixel of the original image indicated by the input video signal S1, and combines the combination pixels The input selection operation of the signal switching unit 13 may be controlled so that pixels based on the first video signal S2 and pixels based on the second video signal S3 are alternately displayed.
Furthermore, the control unit 14 associates each pixel of the display screen with each pixel of the original image indicated by the input video signal on a one-to-one basis, and the pixel based on the first video signal S2 and the second video signal S3. The input selection operation of the signal switching unit 13 may be controlled such that the pixels based on the are alternately arranged and displayed.

Second Embodiment
FIG. 2 is a block diagram showing the configuration of a video processing apparatus according to the second embodiment of the present invention. In FIG. 2, unidirectional arrows indicate the flow of a certain signal, and do not exclude bidirectionality.

Referring to FIG. 2, the video processing device 20 includes a gamma correction unit 1, a gamma look-up table (LTU) 2, an inverse gamma correction unit 3, an inverse gamma LTU 4, a signal switching unit 5, and a control unit 6. The portions of the gamma correction unit 1 and the LTU 2 can be called a first correction unit. The portions of the gamma correction unit 3 and the LTU 4 can be called a second correction unit.

The gamma correction unit 1 outputs a first video signal S2 obtained by performing gamma correction on the input video signal S1. Specifically, the gamma correction unit 1 reads data representing a video tone characteristic (input / output characteristic) for gamma correction from the LTU 2 and performs gamma correction on the input video signal S1 based on the characteristic data. The image gradation characteristic for gamma correction is a curve whose inclination gradually decreases from the dark part to the light part.
The inverse gamma correction unit 3 outputs a second video signal S3 obtained by performing inverse gamma correction on the input video signal S1. Specifically, the inverse gamma correction unit 3 reads out data indicating an image gradation characteristic (input / output characteristic) for inverse gamma correction from the LTU 4 and performs inverse gamma correction on the input image signal S1 based on the characteristic data. Apply. The image gradation characteristic for inverse gamma correction is a curve whose slope gradually increases from the dark portion to the light portion.

The signal switching unit 5 receives the first video signal S2 and the second video signal S3 as inputs, and selectively outputs one of these inputs.
The control unit 6 controls the gamma correction unit 1 and the inverse gamma so that the image based on the first video signal S2 and the image based on the second video signal S3 are alternately output from the signal switching unit 5 for each pixel. The correction operation of the correction unit 3 and the input selection operation of the signal switching unit 5 are controlled.

Next, the operation of the video processing device 20 of the present embodiment will be specifically described.
In the video processing apparatus 20 according to the present embodiment, the control unit 6 displays an image of the first video signal S2 and an image of the second video signal S3 on the display screen on which the output video signal S4 of the signal switching unit 5 is displayed. The operations of the gamma correction unit 1, the inverse gamma correction unit 3 and the signal switching unit 5 are controlled so that they are displayed side by side alternately for each pixel.

Specifically, the control unit 6 sets a combination pixel formed by a plurality of pixels on the display screen as a display pixel unit, and associates each combination pixel with each pixel of the original image indicated by the input video signal S1. Perform image correction processing. In this video correction process, the control unit 6 controls the signal switching unit 5 so that pixels based on the first video signal S2 and pixels based on the second video signal S3 are alternately displayed in combination pixels. Control the input selection operation of

FIG. 3 schematically shows the relationship between the display pixel, the video pixel, and the type of correction when the video correction process is performed. Part (a) of FIG. 3 is a schematic view of a display screen 30 on which the output video signal S4 of the signal switching unit 5 is displayed. Portion (b) of FIG. 3 is an enlarged view of the upper left portion of the display screen 30 of portion (a), and schematically shows the correspondence between display pixels, video pixels, and types of correction for each pixel. It is done.

In the portion (b) of FIG. 3, “correction 1” indicates gamma correction and “correction 2” indicates inverse gamma correction.
In the display screen shown in FIG. 3B (b), the top left pixel is referred to as “display pixel 1-1”. Here, “1” on the left side of the code “1-1” indicates the position (row number) of pixels in the row direction (horizontal direction), and “1” on the right side indicates the position of pixels in the column direction (vertical direction) Column number). In the row direction, the value of the row number increases one by one from left to right. For example, the code of the pixel to the right of the display pixel 1-1 is "1-2". On the other hand, in the column direction, the values of the column numbers increase one by one from top to bottom. For example, the code of the pixel immediately below the display pixel 1-1 is "2-1".

A combined pixel formed by four pixels adjacent to upper, lower, left, and right on the display screen 30 is used as a display pixel unit for displaying each pixel of the original image. For example, the upper left combination pixel 31 of the display screen 30 is composed of four display pixels 1-1, 1-2, 2-1, 2-2 adjacent vertically and horizontally.
The uppermost left pixel of the original image indicated by the input video signal S1 is referred to as “video pixel 1-1”. Here, “1” on the left side of the code “1-1” indicates the position (row number) of pixels in the row direction (horizontal direction) of the original image, and “1” on the right side indicates the column direction of the original image Indicates the position (column number) of the pixel in the vertical direction). In the row direction, the value of the row number increases one by one from left to right. For example, on the original image, the code of the pixel to the right of the video pixel 1-1 is "1-2". On the other hand, in the column direction, the values of the column numbers increase one by one from top to bottom. For example, on the original image, the code of the pixel immediately below the video pixel 1-1 is "2-1".

A combined pixel 31 composed of four display pixels 1-1, 1-2, 2-1, 2-2 corresponds to the video pixel 1-1. In the combination pixel 31, correction 1 is performed on the display pixels 1-1 and 2-2, and correction 2 is performed on the display pixels 1-2 and 2-1.
A combined pixel 31 composed of four display pixels 1-3, 1-4, 2-3 and 2-4 corresponds to the video pixel 1-2. In the combination pixel 31, correction 1 is performed on the display pixels 1-3 and 2-4, and correction 2 is performed on the display pixels 1-4 and 2-3.
The other combination pixels 31 are also displayed so that the image of correction 1 and the image of correction 2 are alternately arranged between adjacent display pixels, as described above.

According to the above video correction process, for example, in the case of the video pixel level of the dark portion in the combination pixel 31 including the four display pixels 1-1, 1-2, 2-1, 2-2, the video signal level of the dark portion It is possible to improve the tone discrimination by raising the brightness of the level that represents black by the display pixels 1-1 and 2-2. Further, when the video pixel 1-1 is at the video signal level of the bright part, it is possible to lower the brightness of the level which represents white by the display pixels 1-2 and 2-1 and to improve the tone discrimination.

In addition, by alternately displaying the image of correction 1 (gamma correction) and the image of correction 2 (inverse gamma correction) on display pixels adjacent vertically and horizontally, inverse gamma correction to the image of gamma correction on the display screen 30 The brightness with the image of is integrated, and a composite image of both images is perceived. As a result, it is possible to improve the tone discrimination between the dark part and the light part while maintaining the tone discrimination of the middle part.

FIG. 4 shows an example of a display screen when the above-mentioned image correction processing is performed. In FIG. 4, the upper part shows the video gradation characteristic, and the lower part shows the gray scale of the display screen according to the video gradation characteristic.
In the video tone characteristics in the upper part of FIG. 4, the vertical axis represents the output tone of the display device, and the horizontal axis represents the tone of the original video (original image). The curve of correction 1 shows tone characteristics used for gamma correction, and the curve of correction 2 shows tone characteristics used for inverse gamma correction. The curve of correction 4 is a combination of the gradation characteristic of gamma correction and the gradation characteristic of inverse gamma correction. Gradation characteristics of correction 1 and gradation characteristics of correction 2 are stored in the gamma LUT 2 and the inverse gamma LUT 4 shown in FIG.

The gray scale in the lower part of FIG. 4 represents the change of the brightness (brightness) according to the composite gradation characteristic of the correction 4 shown in the upper part in ten stages of gradations (1) to (10). The lightness is lower on the gradation (1) side and higher on the gradation (10) side.
Since the brightness of the gamma correction image and the inverse gamma correction image on the display screen 30 is integrated, the gradation characteristic of the correction 4 shown in FIG. 4 is obtained. According to the gradation characteristic of the correction 4, gradation discrimination can be maintained from the dark part to the bright part, as shown by the gray scale in the lower part of FIG.

Third Embodiment
The video processing apparatus according to the third embodiment of the present invention has the same configuration as that shown in FIG. 2, but the video correction process is different from that of the second embodiment.

The control unit 6 associates each pixel of the display screen with each pixel of the original image indicated by the input video signal S1 on a one-to-one basis, and based on the pixel based on the first video signal S2 and the second video signal S3. The input selection operation of the signal switching unit 5 is controlled so that the pixels and the pixels are alternately displayed.
FIG. 5 schematically shows the relationship between the display pixel, the video pixel, and the type of correction when the video correction process is performed. FIG. 5A is a schematic view of a display screen on which the output video signal S4 of the signal switching unit 5 is displayed. Portion (b) of FIG. 5 is an enlarged view of the upper left portion of the display screen of portion (a), and the correspondence between display pixels, video pixels, and types of correction is schematically shown for each pixel. ing. Note that the sign of the display pixel, the sign of the video pixel, the correction 1 and the correction 2 are as described in FIG. 3B (b).

In the example shown in FIG. 5, the display pixel 1-1 corresponds to the video pixel 1-1, and the correction 1 is performed. The display pixel 1-2 adjacent to the right of the display pixel 1-1 corresponds to the video pixel 1-2, and correction 2 is performed. The display pixel 1-3 adjacent to the right of the display pixel 1-2 corresponds to the video pixel 1-3, and correction 1 is performed. The display pixel 1-4 adjacent to the right of the display pixel 1-3 corresponds to the video pixel 1-4, and correction 2 is performed. As described above, in the row direction, video pixels are sequentially switched for each display pixel, and correction 1 and correction 2 are alternately performed.

In addition, the display pixel 2-1 immediately below the display pixel 1-1 corresponds to the video pixel 2-1, and the correction 2 is performed. The display pixel 3-1 immediately below the display pixel 2-1 corresponds to the video pixel 3-1, and correction 1 is performed. The display pixel 4-1 immediately below the display pixel 3-1 corresponds to the video pixel 4-1, and the correction 2 is performed. As described above, in the column direction, video pixels are sequentially switched for each display pixel, and correction 1 and correction 2 are alternately performed.

According to the video processing apparatus of the present embodiment, the display pixels of the display screen 40 correspond to the pixels of the original image indicated by the input video signal on a one-to-one basis. On the display screen 40, an image in which a dark part is floated by gamma correction and an image in which a bright part is sunk by inverse gamma correction are alternately arranged and displayed for each pixel. Also in this case, although the tone discrimination can be improved as in the second embodiment, its effect is smaller than that of the second embodiment. On the other hand, since combinational pixels are not used, the display resolution of the display screen is improved as compared with the second embodiment.

Fourth Embodiment
FIG. 6 is a block diagram showing the configuration of a video display apparatus according to a fourth embodiment of the present invention.

The video display device shown in FIG. 6 has a video processing device 50 and a display unit 51. The video processing device 50 is configured by any of the video processing devices of the first to third embodiments described above.
The display unit 51 displays an image based on the output video signal S4 of the video processing device 50. The display unit 51 may have a light source and a display element that modulates light from the light source based on the video signal S4. The display element is a liquid crystal display or the like. In addition, the display unit 51 may include a light source, an image forming element that modulates light from the light source based on the video signal S4, and a projection lens that projects an image formed by the image forming element. The image forming element is, for example, a liquid crystal display or a DMD (digital micro mirror device).

Each embodiment described above is an example of the present invention, and to the configuration, changes that can be understood by those skilled in the art can be applied without departing from the scope of the invention.

For example, in the first to third embodiments, gamma correction and inverse gamma correction may be performed using image gradation characteristics as shown in FIG.
In FIG. 7, the vertical axis represents the output tone of the display device, and the horizontal axis represents the tone of the original image (original image). The curve of correction 1 shows tone characteristics used for gamma correction, and the curve of correction 2 shows tone characteristics used for inverse gamma correction. The curve of correction 1 of FIG. 7 substantially matches the curve of correction 1 of FIG. On the other hand, the curve of correction 2 in FIG. 7 is a darkened portion with the light portion sunk in comparison with the curve of correction 2 in FIG. By performing the inverse gamma correction using the curve of correction 2 in FIG. 7, the gradation discrimination of the bright portion is further improved.

10 image processing device 11 first correction unit 12 second correction unit 13 signal switching unit 14 control unit

Claims

The change amount of the gradation of the first range on the side where the luminance of the gradation characteristic indicating the gradation of the image is lower than the input video signal is the change of the gradation of the first range of the input video signal The amount of change in gradation in the second range, which is larger than the amount and on the side where the luminance of the gradation characteristic is high, is smaller than the amount of change in gradation in the second range of the input video signal. A first correction unit that outputs a first video signal subjected to the first correction;
The amount of change in gradation of the first range with respect to the input video signal is smaller than the amount of change in gradation of the first range of the input video signal, and the floor of the second range A second correction unit for outputting a second video signal subjected to the second correction such that the amount of change in key tone is larger than the amount of change in gradation of the second range of the input video signal; ,
A signal switching unit which receives the first and second video signals and selectively outputs one of the inputs;
A control unit that controls an input selection operation of the signal switching unit;
The video processing device, wherein the control unit causes the signal switching unit to alternately select an image based on the first video signal and an image based on the second video signal every predetermined number of fields.
The video processing apparatus according to claim 1, wherein the first correction is gamma correction, and the second correction is inverse gamma correction.
The gradation characteristic used for the gamma correction shows a curve whose inclination gradually decreases from the dark part to the light part,
The image processing apparatus according to claim 2, wherein the gradation characteristic used for the inverse gamma correction shows a curve whose inclination gradually increases from the dark part to the light part.
The control unit is configured to alternately display an image based on the first video signal and an image based on the second video signal on a display screen on which an image based on the output video signal of the signal switching unit is displayed. The video processing apparatus according to any one of claims 1 to 3, wherein the input selection operation of the signal switching unit is controlled to be displayed side by side.
The control unit sets a combination pixel formed by a plurality of pixels on a display screen for displaying an image based on an output video signal of the signal switching unit as a display pixel unit, and an original image indicated by each combination pixel and the input video signal Input of the signal switching unit such that pixels based on the first video signal and pixels based on the second video signal are alternately arranged and displayed in association with the respective pixels The video processing apparatus according to any one of claims 1 to 3, which controls a selection operation.
The control unit associates each pixel of the display screen for displaying an image based on the output video signal of the signal switching unit with each pixel of the original image represented by the input video signal on a one-to-one basis, and the first video The input selection operation of the signal switching unit is controlled so that a pixel based on a signal and a pixel based on the second video signal are alternately displayed. Video processing device.
A video processing apparatus according to any one of claims 1 to 6.
A display unit configured to display an image based on an output video signal of the video processing apparatus.
The change amount of the gradation of the first range on the side where the luminance of the gradation characteristic indicating the gradation of the image is lower than the input video signal is the change of the gradation of the first range of the input video signal The amount of change in gradation in the second range, which is larger than the amount and on the side where the luminance of the gradation characteristic is high, is smaller than the amount of change in gradation in the second range of the input video signal. To generate the first video signal subjected to the first correction,
The amount of change in gradation of the first range with respect to the input video signal is smaller than the amount of change in gradation of the first range of the input video signal, and the floor of the second range Generating a second video signal subjected to the second correction such that the amount of change in key tone is larger than the amount of change in gradation of the second range of the input video signal;
A video processing method for alternately outputting an image based on the first video signal and an image based on the second video signal for each predetermined number of strokes.