WO2010116432A1

WO2010116432A1 - Image processing apparatus, display apparatus, image processing method, program, and recording medium

Info

Publication number: WO2010116432A1
Application number: PCT/JP2009/006859
Authority: WO
Inventors: 宮田英利; 山根康邦
Original assignee: シャープ株式会社
Priority date: 2009-04-10
Filing date: 2009-12-14
Publication date: 2010-10-14

Abstract

An image processing apparatus wherein the resolution of R, G and B input image data is upscaled to a four-fold high resolution for display on a liquid crystal display panel (2). A pixel (21) before upscaling corresponds to four divided pixels (P1-P4) after upscaling, and each of the divided pixels (P1-P4) consists of a plurality of subpixels (R1, G1, B1; R2, G2, B2; R3, G3, B3; R4, G4, B4) corresponding to R, G and B. In a divided pixel (P1), the gray-scale values of the subpixels (R1, G1, B1) are redistributed among the subpixels (R1, G1, B1) in the divided pixel (P1), while in the pixel (22), for each of R, G and B, the gray-scale values are redistributed among the subpixels (R1-R4, G1-G4, B1-B4) in the pixel (22). In this way, in the image processing apparatus for converting the resolution of input image data to a high resolution, high definition images can be generated without complicating the drive process, while the view angle can be improved.

Description

Image processing apparatus, display apparatus, image processing method, program, and recording medium

The present invention relates to an image processing apparatus and an image processing method for upscaling the resolution of input image data to a high resolution.

Conventionally, problems of viewing angle characteristics in liquid crystal display panels have been taken up. Specifically, the luminance and chromaticity are different between when the liquid crystal display panel is viewed from an oblique direction and when viewed from the front direction. In particular, in the VA mode liquid crystal display panel, as shown in FIG. 9, the output signal luminance relative to the input signal luminance when viewed from an oblique direction is higher than the output signal luminance relative to the input signal luminance when viewed from the front direction. There is a problem that the brightness increases and so-called brightness rises.

For example, a pixel division method described in Patent Document 1 is generally known as a method for solving such problems related to viewing angle characteristics. The pixel dividing method is a technique in which one pixel is divided into a plurality of regions, and different voltages are applied to the divided regions (divided pixels). According to this method, the brightness floating can be suppressed and the viewing angle characteristics can be improved.

Japanese Patent Publication “Japanese Patent Laid-Open No. 4-102830 (published on April 3, 1992)”

In addition, for liquid crystal display panels, conventionally, much research has been conducted on upscaling technology for converting the resolution of input image data to a high resolution to improve the image quality.

In recent years, the resolution of a liquid crystal display panel has been greatly increased, and a so-called 4K2K panel having a resolution of 4096 (horizontal) × 2160 (vertical) has been developed. For example, when a high-definition 1920 × 1080 video signal (image data) is input, an upscaling process is performed to display a resolution (3840 × 2160) that is four times the input image data (twice vertically and horizontally). Can be obtained.

When the above pixel division method is applied to a high-resolution liquid crystal display panel to which such an upscaling technology is applied in order to improve the viewing angle, the driving process becomes complicated, so the writing time to the pixel is shortened, Insufficient charging occurs. This is because a different voltage must be applied to each of the divided pixels whose number has increased due to an increase in the resolution of the panel.

As described above, in the conventional liquid crystal display panel, it has been difficult to generate a high-definition image and improve the viewing angle without complicating the driving process.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a high-resolution image processing apparatus that converts the resolution of input image data to a high resolution without complicating drive processing. An object of the present invention is to provide an image processing apparatus capable of generating an image and improving the viewing angle.

In order to solve the above-described problem, the image processing apparatus of the present invention includes an upscaling processing unit for upscaling the resolution of RGB input image data to a high resolution that is n times higher. An image processing apparatus to be displayed on a display unit, wherein one pixel before upscaling corresponds to n divided pixels after upscaling, and each divided pixel includes a plurality of subpixels corresponding to RGB. Then, with respect to the input image data corresponding to one pixel, the gradation value that has been upscaled by the upscaling processing unit and assigned to the plurality of subpixels corresponding to the pixel is redistributed among the subpixels. A redistribution processing unit, wherein the redistribution processing unit regards each of the sub-images in each divided pixel when the n divided pixels after the upscaling are regarded as one pixel. The gradation value assigned to each pixel is redistributed among the sub-pixels in the divided pixel, and the gradation value assigned to each sub-pixel is changed between the sub-pixels in the pixel for each RGB. It is characterized by redistributing with.

In the above configuration, the gradation values assigned to the sub-pixels corresponding to RGB that have been upscaled are redistributed among the sub-pixels in the divided pixels, and re-distributed between the sub-pixels in the pixel for each RGB. Distribute. Therefore, for example, before and after the redistribution, the subpixels of each of the RGB of one whole pixel (in one pixel) without changing the luminance of one whole divided pixel and the chromaticity of one whole pixel. The luminance difference can be increased between sub-pixels of the same color. Thereby, the viewing angle can be improved while obtaining a high-definition image by the upscaling process. In the above configuration, since the viewing angle can be improved by distributing the gradation value among the sub-pixels, there is no need to newly divide the pixel to improve the viewing angle, and the panel transmittance is reduced and writing to the pixel is performed. There is no shortage of time.

In order to solve the above-described problems, a display device according to the present invention includes the image processing device and a display unit that displays image data upscaled by the image processing device.

This makes it possible to display high-definition and high-quality images with improved viewing angles.

In order to solve the above problems, the image processing method of the present invention includes an upscaling process step for upscaling the resolution of RGB input image data to n times higher resolution, and displays the upscaled image data. In this image processing method, one pixel before upscaling corresponds to n divided pixels after upscaling, and each divided pixel includes a plurality of subpixels corresponding to RGB. Redistribution processing for redistributing gradation values assigned to a plurality of sub-pixels corresponding to the pixel after the up-scale processing step is performed on the input image data corresponding to one pixel. And a display step of displaying image data on the display unit based on the gradation values redistributed by the redistribution processing step In the redistribution processing step, when the n divided pixels after the upscaling are regarded as one pixel, the gradation value assigned to each sub pixel in each divided pixel is changed to the sub-pixel in the divided pixel. In addition to redistribution among the pixels, the gradation value assigned to each subpixel in each pixel is redistributed among the subpixels in the pixel for each RGB.

According to the image processing method, it is possible to obtain the effect produced by the image processing apparatus. That is, a high-definition image can be generated and the viewing angle can be improved without complicating the driving process.

The image processing apparatus may be realized by a computer. In this case, a program that causes the image processing apparatus to be realized by the computer by causing the computer to operate as each unit, and a computer reading that records the program. Possible recording media are also included in the scope of the present invention.

Other objects, features, and superior points of the present invention will be fully understood from the following description. The advantages of the present invention will become apparent from the following description with reference to the accompanying drawings.

As described above, in the image processing apparatus and the image processing method of the present invention, in each divided pixel, the gradation value assigned to each sub-pixel is redistributed among the sub-pixels in the divided pixel, and each pixel In FIG. 5, the gradation value assigned to each sub-pixel is redistributed among the sub-pixels in the pixel for each RGB.

Therefore, according to the image processing apparatus and the image processing method of the present invention, it is possible to generate a high-definition image and improve the viewing angle without complicating the driving process.

It is a block diagram which shows schematic structure of the display apparatus provided with the image processing apparatus which concerns on this invention. It is a schematic diagram for demonstrating the processing content of the image processing apparatus of FIG. It is a schematic diagram which shows the specific example of the processing content of the image processing apparatus of FIG. It is a schematic diagram which shows the specific example of the processing content of the image processing apparatus of FIG. It is a graph which shows the relationship between the gradation value of input image data, and a brightness | luminance equivalent value. 3 is a graph showing luminance characteristics when displayed by image data after redistribution obtained by the image processing apparatus of FIG. 1. 3 is a graph showing luminance characteristics when displayed by image data after redistribution obtained by the image processing apparatus of FIG. 1. It is a graph which shows the relationship between a spatial frequency and contrast sensitivity. It is a graph which shows the luminance characteristic at the time of displaying with the image data after redistribution obtained by the conventional image processing apparatus.

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

FIG. 1 is a block diagram showing a schematic configuration of a display device 1 according to the present embodiment. As shown in this figure, the display device 1 includes an image processing device 10 and a liquid crystal display panel (display unit) 2.

The image processing apparatus 10 includes an upscale circuit (upscale processing unit) 11, a redistribution circuit (redistribution processing unit) 12, and a liquid crystal drive circuit 13.

The upscaling circuit 11 performs upscaling processing on the video signal X (image data) input to the image processing apparatus 10 and outputs upscaled image data (upscaled image data) to the redistribution circuit 12. . The upscale circuit 11 includes a division processing unit (not shown) that divides input image data into a plurality of divided image data. In the present embodiment, as an example, it is assumed that 2K1K class high-definition data is input to the upscale circuit 11. Details of the upscaling process will be described later.

The redistribution circuit 12 performs redistribution processing for redistributing the gradation values of the upscaled image data input from the upscale circuit 11, and drives the redistributed image data (image data after redistribution) by liquid crystal Output to the circuit 13. Details of the redistribution processing will be described later.

The liquid crystal drive circuit 13 controls the liquid crystal display panel 2 on the basis of the redistributed image data (tone value) input from the redistribution circuit 12 and causes the liquid crystal display panel 2 to display the redistributed image.

The liquid crystal display panel 2 is controlled by the liquid crystal drive circuit 13 and displays an image corresponding to the image data that has been upscaled and redistributed by the image processing apparatus 10. In this embodiment, a liquid crystal display panel having 4096 pixels in the horizontal direction and 2160 pixels in the vertical direction (4K2K class) is used.

When the size of the input image data for the image processing apparatus 10 is 1920 × 1080 and the display size of the liquid crystal display panel 2 is 4096 × 2160, the input image data is upscaled (expanded) twice to 3840 ×. 2160. In this case, since the size in the horizontal direction (3840 dots) is smaller than the display size (4096 dots), it is necessary to display the image of the left half divided area by shifting to the right by 2048-1920 = 128 dots. . The correction process for shifting the left half image to the right may be performed in any part in the image processing apparatus 10. However, the display capacity of the liquid crystal display panel is not limited to this.

In this embodiment, a liquid crystal display panel is used as the display unit. However, the present invention is not limited to this. For example, a display unit including a plasma display, an organic EL display, or a CRT may be used. Instead of the circuit 13, a display control unit corresponding to the display unit may be provided.

Next, specific processing contents of the image processing apparatus 10 according to the present embodiment will be described together with details of the upscaling process and the redistribution process.

As described above, when the 2K1K video signal X is input as the input image (original image) data, the image processing apparatus 10 performs the upscaling process on the input image data, and the 4K2K video signal X is input. Image data after upscaling is generated, and the redistribution circuit 12 performs a process of redistributing gradation values on the image data after upscaling to generate image data after redistribution. Thereafter, the liquid crystal driving circuit 13 generates a video signal corresponding to the redistributed image data (gradation value) in which the gradation value is redistributed (converted) by the redistribution circuit 12, and an image corresponding to the video signal is generated. Is displayed on the liquid crystal display panel 2.

FIG. 2 is a schematic diagram for explaining the processing contents of the image processing apparatus 10. Reference numeral 21 in this figure indicates image data corresponding to one pixel of 2K1K input image (original image) data, and reference numeral 22 indicates 4K2K post-upscale image data that has been upscaled by the upscale circuit 11. Is shown. For convenience, reference numeral 21 denotes a pixel before upscaling, and reference numeral 22 also denotes a pixel after upscaling. In addition, here, as an example, as illustrated in FIG. 2, description will be given focusing on one pixel among a plurality of pixels constituting the input image data.

First, RGB original image data (input data) 21 corresponding to one pixel is input to the upscale circuit 11 (see FIG. 1) and upscaled four times (upscale processing step). As shown in FIG. 2, the input data PR is upscaled to R subpixel data R1, R subpixel data R2, R subpixel data R3, R subpixel data R4, and the input data PG is G subpixel data G1. , G subpixel data G2, G subpixel data G3, G subpixel data G4, and the input data PB is B subpixel data B1, B subpixel data B2, B subpixel data B3, B subpixel data. Upscaled to B4.

Here, if the three sub-pixels (R, G, and B) are regarded as one group, one upscaled pixel corresponding to the input data 21 is composed of four divided pixels P1, P2, P3, and P4. Will be. That is, as indicated by reference numeral 22 in FIG. 2, the divided pixel P1 is composed of sub-pixels R1, G1, and B1, the divided pixel P2 is composed of sub-pixels R2, G2, and B2, and the divided pixel P3 is sub-pixel R3. The divided pixel P4 includes sub-pixels R4, G4, and B4.

The luminance values Y1 to Y4 of the divided pixels P1 to P4 after upscaling are expressed by the following equations. Note that LR (x), LG (x), and LB (x) are functions that convert the gradation value x into a luminance value (cd / m ² ). Hereinafter, for convenience, the gradation value x of the sub-pixel R1 is defined as R1, and the gradation value x of the sub-pixel G1 is defined as G1.
Y1 = LR (R1) + LG (G1) + LB (B1) (1)
Y2 = LR (R2) + LG (G2) + LB (B2) (2)
Y3 = LR (R3) + LG (G3) + LB (B3) (3)
Y4 = LR (R4) + LG (G4) + LB (B4) (4)
Next, when the upscaled image data is input to the redistribution circuit 12 (see FIG. 1), the redistribution circuit 12 performs a conversion process for each RGB pixel as shown in FIG. Thus, the gradation values are redistributed.
R1 → R1 ′, R2 → R2 ′, R3 → R3 ′, R4 → R4 ′
G1 → G1 ′, G2 → G2 ′, G3 → G3 ′, G4 → G4 ′
B1 → B1 ′, B2 → B2 ′, B3 → B3 ′, B4 → B4 ′
Therefore, the luminance values Y1 ′ to Y4 ′ of the divided pixels P1 to P4 after redistribution are expressed by the following equations.
Y1 '= LR (R1') + LG (G1 ') + LB (B1') (5)
Y2 '= LR (R2') + LG (G2 ') + LB (B2') (6)
Y3 '= LR (R3') + LG (G3 ') + LB (B3') (7)
Y4 '= LR (R4') + LG (G4 ') + LB (B4') (8)
Here, the redistribution circuit 12 has the luminance represented by the image data of the upscaled divided pixels P1 to P4 (divided pixels P1 to P4 before redistribution) and the image of the divided pixels P1 to P4 after redistribution. In each divided pixel, the luminance values are redistributed between RGB so that the luminance represented by the data is equal to each other (does not change). Specifically, for the divided pixel P1, the luminance represented by the image data R1, G1, B1 before redistribution and the luminance represented by the image data R1 ′, G1 ′, B1 ′ after redistribution are mutually The luminance values of the image data R1, G1, and B1 are distributed (increased or decreased) to each other so as to be equal. For the divided pixel P2, the luminance represented by the image data R2, G2, B2 before redistribution and the luminance represented by the image data R2 ′, G2 ′, B2 ′ after redistribution are equal to each other. The luminance values of the image data R2, G2, and B2 are distributed (increased or decreased) to each other. For the divided pixel P3, the luminance represented by the image data R3, G3, and B3 before redistribution and the luminance represented by the image data R3 ′, G3 ′, and B3 ′ after redistribution are equal to each other. The luminance values of the image data R3, G3, and B3 are distributed (increased or decreased) to each other. For the divided pixel P4, the luminance represented by the image data R4, G4, and B4 before redistribution and the luminance represented by the image data R4 ′, G4 ′, and B4 ′ after redistribution are equal to each other. The luminance values of the image data R4, G4, and B4 are distributed (increased or decreased) to each other.

That is, the redistribution processing (redistribution processing step) of the luminance value among the sub-pixels RGB is performed in each divided pixel so as to satisfy the following expressions with respect to the above expressions (1) to (8).
Y1 = Y1 ′ (9)
Y2 = Y2 ′ (10)
Y3 = Y3 ′ (11)
Y4 = Y4 ′ (12)
Also, the redistribution circuit 12 is a color represented by image data (image data after upscaling: R1 to R4, G1 to G4, B1 to B4) of each subpixel after upscaling (subpixel before redistribution). And the chromaticity represented by the image data of each subpixel after redistribution (image data after redistribution: R1 ′ to R4 ′, G1 ′ to G4 ′, B1 ′ to B4 ′) for each RGB pixel The luminance values are redistributed among the sub-pixels of each color so as to be equal to each other. Specifically, for the R pixel, the luminance is represented by the sum of luminance represented by the image data R1, R2, R3, and R4 before redistribution, and the image data R1 ′, R2 ′, R3 ′, and R4 ′ after redistribution. The luminance values of the image data R1, R2, R3, and R4 are redistributed with each other so that the total sum of the luminances is equal to each other. For G pixels, the sum of the brightness represented by the image data G1, G2, G3, and G4 before redistribution and the sum of the brightness represented by the image data G1 ′, G2 ′, G3 ′, and G4 ′ after redistribution Are redistributed to each other so that the brightness values of the image data G1, G2, G3, and G4 are equal to each other. For the B pixel, the sum of the brightness represented by the image data B1, B2, B3, B4 before redistribution and the sum of the brightness represented by the image data B1 ', B2', B3 ', B4' after redistribution Are redistributed to each other so that the brightness values of the image data B1, B2, B3, and B4 are equal to each other. By making the sum of the luminances of R, G, and B the same before and after redistribution, the chromaticity can be redistributed equally.

The values CR, CG, and CB corresponding to the luminance of each color represented by the image data of each sub-pixel after upscaling (upscaled image data: R1 to R4, G1 to G4, and B1 to B4) are given by expressed.
CR = LR (R1) + LR (R2) + LR (R3) + LR (R4) (13)
CG = LG (G1) + LG (G2) + LG (G3) + LG (G4) (14)
CB = LB (B1) + LB (B2) + LB (B3) + LB (B4) (15)
Values CR ′ and CG corresponding to the luminance of each color represented by the image data of each subpixel after redistribution (image data after redistribution: R1 ′ to R4 ′, G1 ′ to G4 ′, B1 ′ to B4 ′) ', CB' is expressed by the following equation.
CR ′ = LR (R1 ′) + LR (R2 ′) + LR (R3 ′) + LR (R4 ′) (16)
CG ′ = LG (G1 ′) + LG (G2 ′) + LG (G3 ′) + LG (G4 ′) (17)
CB ′ = LB (B1 ′) + LB (B2 ′) + LB (B3 ′) + LB (B4 ′) (18)
Then, within one pixel, luminance value redistribution processing is performed among a plurality of R sub-pixels, and luminance value redistribution processing is performed among a plurality of G sub-pixels so that the following equation is satisfied. A luminance value redistribution process (redistribution process step) is performed between the B sub-pixels.
CR = CR ′ (19)
CG = CG '(20)
CB = CB '(21)
Here, LR (x), LG (x), and LB (x) are defined as values corresponding to output luminances for the R, G, and B gradation values x, respectively. For example, LR (x) corresponds to the output luminance when a data signal (gradation value x) is input to the R pixel of the liquid crystal display panel and a 0 data signal is input to the G pixel and the B pixel. Therefore, when the luminance value in this case the L _R,
LR (x) = L _R −L ₀
Is defined as follows. Here, L ₀ corresponds to output luminance when a data signal of 0 is input to all of the R pixel, G pixel, and B pixel (note that the liquid crystal panel has a slight luminance output even when the input signal is 0). LG (x) and LB (x) are the same, and are functions for obtaining a luminance equivalent value. In addition, since the characteristics of this function vary depending on the specifications of the liquid crystal display panel, it is necessary to match each characteristic.

Based on the gradation values (R1 ′ to R4 ′, G1 ′ to G4 ′, B1 ′ to B4 ′ in FIG. 2) obtained by inverse conversion from the luminance redistributed by the redistribution processing, the liquid crystal display panel 2 Image data is displayed (display step).

According to the above configuration, the gradation value assigned to the subpixels corresponding to RGB by the upscaling processing unit can be redistributed among the subpixels in the divided pixels. Further, the gradation value assigned to the sub-pixel can be redistributed among the sub-pixels in the pixel for each RGB. Therefore, for example, before and after the redistribution, the subpixels of the respective RGB (the same color) of each of the entire divided pixels are not changed without changing the luminance of the entire divided pixel and the chromaticity of the entire pixel. The luminance difference between the sub-pixels) can be increased. Thereby, the viewing angle can be improved while obtaining a high-definition image by the upscaling process. In addition, since RGB chromaticity can be adjusted, display quality is not deteriorated. Note that the gradation value redistributed in the redistribution processing unit is determined according to the luminance and the pixel size.

Further, according to the above configuration, it is not necessary to add a new subpixel for each subpixel as in the conventional pixel dividing method, so that the driving of the liquid crystal display panel is not complicated, and the pixel The aperture ratio (transmittance) does not decrease.

Here, in order to increase the viewing angle improvement effect, the redistribution circuit 12 increases the scale difference between the subpixels of the luminance represented by each subpixel after the redistribution by the redistribution circuit 12 in each pixel. It is preferable to redistribute the gradation values of the sub-pixels so that the difference between the sub-pixels in luminance represented by each sub-pixel after the upscaling by the circuit 11 is greater. Specifically, for example, in the pixel 22, the luminance value (LR (R1 ')) of the sub-pixel R1' after redistribution, the luminance value (LR (R2 ')) of the sub-pixel R2', and the sub-pixel R3 ' The difference between the luminance value (LR (R3 ′)) and the luminance value (LR (R4 ′)) of the sub-pixel R4 ′ is the difference between the luminance value (LR (R1)) of the sub-pixel R1 after the upscaling and the sub-pixel R2. The luminance between the sub-pixels is larger than the difference between the luminance value (LR (R2)), the luminance value of the sub-pixel R3 (LR (R3)) and the luminance value of the sub-pixel R4 (LR (R4)). Redistribute values. More specifically, in the pixel 22, after redistribution, the luminance value (LR (R1 ')) of the sub-pixel R1', the luminance value (LR (R2 ')) of the sub-pixel R2', and the luminance of the sub-pixel R3 ' Out of the value (LR (R3 ′)) and the luminance value (LR (R4 ′)) of the sub-pixel R4 ′, the luminance value of the sub-pixel having the maximum luminance value and the luminance value of the sub-pixel having the minimum luminance value Are the luminance value of the sub-pixel R1 (LR (R1)), the luminance value of the sub-pixel R2 (LR (R2)), the luminance value of the sub-pixel R3 (LR (R3)), and Of the luminance values (LR (R4)) of the sub-pixel R4, the sub-pixel is set to be larger than the difference between the luminance value of the sub-pixel having the maximum luminance value and the luminance value of the sub-pixel having the minimum luminance value. Redistribute luminance values between them. Thereby, the viewing angle improvement effect can be enhanced.

Further, since one divided pixel is composed of RGB sub-pixels, a distribution ratio may be set for each sub-pixel and redistribution processing may be performed individually. Since the contribution to luminance differs for each sub-pixel, even if the luminance difference between sub-pixels is a high luminance difference of 100 cd / m ² or more, for example, the luminance change before and after redistribution per divided pixel is Can be suppressed. Therefore, redistribution processing is possible even for such a high luminance difference.

In addition, since the redistribution processing can be performed for each sub-pixel, the redistribution processing function can be turned on / off for each sub-pixel.

For example, according to the CIE color system, the luminance ratio of RGB is
LR (R pixel): LR (G pixel): LR (B pixel) = 1: 4.5907: 0.0601
Therefore, in the B pixel having a small contribution to luminance, it can be redistributed with a larger gradation difference. As a result, it is possible to further improve the effect of increasing the definition of the display image and improving the viewing angle without changing the luminance before and after redistribution of the upscaled image data.

Here, as shown in FIG. 3, the redistribution circuit 12 matches the center position of the luminance in the divided pixel after the redistribution with the center position of the divided pixel, and the chromaticity central position in the pixel after the redistribution. However, it is preferable to perform the redistribution process so as to coincide with the center position of the pixel. As a result, the sense of resolution when viewed by humans is not impaired, and a change in chromaticity is not recognized. In other words, since the center of luminance resolution is at the center of each divided pixel, there is no change in the sense of resolution, and since the center of chromaticity is at the center of the pixel (four-divided pixel), chromaticity is also redistributed to humans. It looks the same before and after.

In the conventional RGB liquid crystal display panel, although the center of luminance is not at the center of the divided pixel, the center of luminance is often the center of the divided pixel by centering on the G pixel having high luminance. I have to.

A specific example of the above redistribution processing will be described below.

As shown in FIG. 4, data signals R1, G1, and B1 are input to the divided pixel P1, data signals R2, G2, and B2 are input to the divided pixel P2, and a data signal R3 is input to the divided pixel P3. G3 and B3 are input, and data signals R4, G4, and B4 are input to the divided pixel P4. The redistribution processing is executed, and the divided pixel P1 becomes the data signal R1 ′ / G1 ′ / B1 ′, the divided pixel P2 becomes the data signal R2 ′ / G2 ′ / B2 ′, and the divided pixel P3 receives the data signal. R3 ′, G3 ′, B3 ′, and the divided pixel P4 becomes the data signal R4 ′, G4 ′, B4 ′.

At this time, the luminance in each divided pixel is concentrated on the G sub-pixel located at the center of RGB for each divided pixel or on the R sub-pixel and the B sub-pixel. For example, as shown in FIG. 4, in the divided pixel P1, the luminance is concentrated on the G sub pixel, in the divided pixel P2, the luminance is concentrated on the R sub pixel and the B sub pixel, and in the divided pixel P3, the luminance is set on the R sub pixel. In the divided pixel P4, the luminance is concentrated on the G sub-pixel. By distributing the luminance in this way, the center of luminance becomes the center of each divided pixel, and the center of chromaticity becomes the center of the four divided pixels P1 to P4 (see FIG. 3). Note that the R pixel and the B pixel may not be concentrated because the luminance is lower than that of the G pixel.

Here, a specific example will be given in the case where the gradation data value input to the sub-pixel and the luminance equivalent value have the relationship shown in FIG. Here, it is assumed that the input gradation data is 8 bits, and the input signal has 0 to 255 gradations. When the gradation data values (R, G, B) input to the R, G, B sub-pixels in the four divided pixels are (180, 150, 80), the sub-pixels from the graph of FIG. The luminance equivalent value of the pixel is the following value.
R subpixel: LR (180) = 29.6
G subpixel: LG (150) = 66.8
B subpixel: LB (80) = 1.7
Further, the luminance equivalent values Y1, Y2, Y3, and Y4 of the divided pixels P1, P2, P3, and P4 are the following values from the above equations (1) to (4).
Y1 = LR (R1) + LG (G1) + LB (B1)
= 29.6 + 66.8 + 1.7
= 98.1
Here, because Y1 = Y2 = Y3 = Y4,
Y1 = Y2 = Y3 = Y4 = 98.1
It becomes.

Further, the chromaticities CR, CG, and CB represented by the gradation data values of the sub-pixels RGB after the upscaling have the following values from the above equations (13) to (15).
CR = LR (R1) + LR (R2) + LR (R3) + LR (R4)
= 29.6 + 29.6 + 29.6 + 29.6
= 118.4
CG = LG (G1) + LG (G2) + LG (G3) + LG (G4)
= 66.8 + 66.8 + 66.8 + 66.8
= 267.2
CB = LB (B1) + LB (B2) + LB (B3) + LB (B4)
= 1.7 + 1.7 + 1.7 + 1.7
= 6.8
In the redistribution processing, as described above, the respective luminance values in the respective divided pixels do not change before and after the redistribution processing (the above formulas (9) to (12)), and the chromaticity for each RGB in one pixel. Is redistributed so that the value does not change before and after the redistribution process (the above formulas (19) to (21)). Here, the luminance value of each sub-pixel is redistributed as follows.
LR (R1 ′) = 29.6−29.6 = 0
LG (G1 ′) = 66.8 + 29.6 + 1.7 = 98.1
LB (B1 ') = 1.7-1.7 = 0
LR (R2 ') = 29.6 + 29.6 = 59.2
LG (G2 ') = 66.8-29.6-1.7 = 35.5
LB (B2 ′) = 1.7 + 1.7 = 3.4
LR (R3 ') = 29.6 + 29.6 = 59.2
LG (G3 ') = 66.8-29.6-1.7 = 35.5
LB (B3 ′) = 1.7 + 1.7 = 3.4
LR (R4 ') = 29.6-29.6 = 0
LG (G4 ′) = 66.8 + 29.6 + 1.7 = 98.1
LB (B4 ') = 1.7-1.7 = 0
Thereby, the luminance values Y1 ′ to Y4 ′ of the divided pixels P1 to P4 after the redistribution become the following values from the above equations (5) to (8).
Y1 '= LR (R1') + LG (G1 ') + LB (B1')
= 0 + 98.1 + 0
= 98.1
Y2 '= LR (R2') + LG (G2 ') + LB (B2')
= 59.2 + 35.5 + 3.4
= 98.1
Y3 '= LR (R3') + LG (G3 ') + LB (B3')
= 59.2 + 35.5 + 3.4
= 98.1
Y4 '= LR (R4') + LG (G4 ') + LB (B4')
= 0 + 98.1 + 0
= 98.1
Therefore, the above formulas (9) to (12) are satisfied. Further, the chromaticities CR ′, CG ′, CB ′ represented by the gradation data values of the sub-pixels RGB after redistribution have the following values from the above equations (16) to (18).
CR ′ = LR (R1 ′) + LR (R2 ′) + LR (R3 ′) + LR (R4 ′)
= 0 + 59.2 + 59.2 + 0
= 118.4
CG ′ = LG (G1 ′) + LG (G2 ′) + LG (G3 ′) + LG (G4 ′)
= 98.1 + 35.5 + 35.5 + 98.1
= 267.2
CB '= LB (B1') + LB (B2 ') + LB (B3') + LB (B4 ')
= 0 + 3.4 + 3.4 + 0
= 6.8
Therefore, the above expressions (19) to (21) are satisfied. When the luminance values Y1 'to Y4' after the redistribution are converted into gradation data values (R ', G', B ') from the graph of FIG. 5, the following values are obtained. Then, based on the obtained gradation data value, image data is displayed on the liquid crystal display panel 2.
Divided pixel P1: (R1 ′, G1 ′, B1 ′) = (0, 178, 0)
Divided pixel P2: (R2 ′, G2 ′, B2 ′) = (246, 112, 109)
Divided pixel P3: (R3 ′, G3 ′, B3 ′) = (246, 112, 109)
Divided pixel P4: (R4 ′, G4 ′, B4 ′) = (0, 178, 0)
As described above, the redistribution circuit 12 is configured such that the luminance represented by one divided pixel after upscaling and the luminance represented by the divided pixels after redistribution become equal to each other, and 1 after the upscaling. The gradation values (R1 to R4, G1 to G4, B1) assigned to the sub-pixels so that the chromaticity represented by one pixel and the chromaticity represented by the pixel after redistribution are equal to each other. To B4) are redistributed to the gradation values (R1 ′ to R4 ′, G1 ′ to G4 ′, B1 ′ to B4 ′).

FIG. 6 shows the luminance characteristics obtained by the above processing. In this figure, a graph indicated by a broken line (60 °) indicates a luminance characteristic when the redistribution processing is not performed after upscaling, and a graph indicated by a solid line is the case when the redistribution processing is performed after upscaling. The luminance characteristic is shown. The configuration in which the redistribution processing is performed is closer to the luminance characteristic (graph indicated by the dotted line) when the liquid crystal display panel is viewed from the front direction than the configuration in which the redistribution processing is not performed. It is shown that the characteristics are improved.

FIG. 7 is a graph comparing the luminance characteristics (graphs indicated by dotted lines) in the conventional configuration shown in FIG. 9 with the luminance characteristics (graphs indicated by broken lines) in the configuration of the present invention. As is clear from this figure, according to the configuration of the present invention, whitening can be suppressed and the viewing angle characteristics can be improved as compared with the conventional configuration.

As described above, in the image processing apparatus 10 according to the present embodiment, a redistribution process for improving the viewing angle is performed on the upscaled video signal, thereby obtaining a high-definition image and improving the viewing angle. can do.

In the present invention, in consideration of visual characteristics related to human chromaticity, different voltage applications can be applied without dividing a pixel region by effectively using sub-picture elements (RGB) of a plurality of picture elements (four picture elements). The RGB input data values are redistributed so that the viewing angle characteristics are improved. In particular, by performing the redistribution processing of the viewing angle improvement of the present invention on an image signal that has been upscaled from FHD to 4 times QFHD resolution, the viewing angle characteristics can be improved without impairing the resolution improvement effect. Can do.

Generally, when upscaling is performed, the resolution is upscaled in the luminance component, and the color component is not upscaled. This is because, in human visual characteristics, the spatial resolution characteristic is different from the luminance characteristic and the color characteristic as shown in FIG. 8, and the color contrast frequency characteristic occurs at a lower spatial frequency than the luminance characteristic (Visual Information Processing Handbook). This is considered to be because of the Japanese visual society edition p.232). That is, in general, on the pixel scale of a display such as a TV, human visual characteristics are inferior in chromaticity resolution characteristics compared to luminance. Actually, the current digital TV broadcast signal has less than half the color information with respect to the luminance information. In the display on the current display, for example, in the case of the same luminance and chromaticity, R, G, and B output the same luminance in adjacent pixels. However, in consideration of the above visual characteristics, R, G, and B do not necessarily have to be the same, and accurate chromaticity may be output as a whole. Even when adjacent pixels have different luminance, the conditions are the same as long as the chromaticity is appropriate at a level that can be visually recognized as chromaticity.

In the present invention, using these characteristics, the luminance is redistributed in each of the RGB sub-pixels. Further, in the case of display with upscaling four times, the luminance information is quadrupled by the upscaling, but there is no problem visually even if the color information displays one color with four divided pixels. In many cases, it is possible to readjust the luminance of the RGB sub-pixels in the four-divided pixels and redistribute them so that the luminance difference between the divided pixels becomes large.

Here, in the above description, the configuration in which the size of the upscale is four times (twice in the vertical and horizontal directions) is described, but the present invention is not limited to this. Is obtained.

When one pixel is composed of RGB sub-pixels, a redistribution process can be performed individually by setting a distribution ratio for each sub-pixel. Since the contribution to luminance differs for each sub-pixel, even if the luminance difference between the divided pixels is a high luminance difference of, for example, 100 cd / m ² or more, the luminance change before and after redistribution per pixel is suppressed. be able to. Therefore, redistribution processing is possible even for such a high luminance difference.

In addition, since redistribution processing can be performed for each sub-pixel, a configuration in which the redistribution processing function is turned ON / OFF for each sub-pixel can be employed. For example, according to the CIE color system, the luminance ratio of RGB is
L (R pixel): L (G pixel): L (B pixel) = 1: 4.5907: 0.0601
Therefore, B pixels that have a small contribution to luminance can be redistributed with a larger luminance difference. As a result, it is possible to further improve the effect of increasing the definition of the display image and improving the viewing angle without changing the luminance before and after redistribution of the upscaled image data.

Incidentally, in FIG. 1, the liquid crystal drive circuit 13 is shown as one block. However, the present invention is not limited to this, and the liquid crystal drive circuit 13 may be composed of a plurality of blocks. For example, a plurality of upscale circuits 11 are provided, and a plurality of redistribution circuits 12 and liquid crystal drive circuits 13 are provided corresponding to the plurality of upscale circuits 11, and the divided regions in the liquid crystal display panel 2 are formed by these liquid crystal drive circuits. You may make it drive. When the entire liquid crystal display panel 2 is driven by a single liquid crystal drive circuit 13, the drive timing of each region can be easily matched, so that there is an advantage of good controllability, while the number of input / output pins increases. The circuit size (IC size) becomes large. Further, when a plurality of liquid crystal driving circuits 13 are provided according to the divided areas, there is an advantage that the chip size can be reduced (in particular, in the case of the present embodiment, each divided area is a 2K1K class, so that the conventional 2K1K class display device is provided. It is economical because the 2K control chip used can be used.) On the other hand, it is necessary to provide an arbitration circuit for maintaining the synchronization of the liquid crystal drive circuits 13.

Further, each circuit (each block) constituting the image processing apparatus 10 may be realized by software using a processor such as a CPU. That is, the image processing apparatus 10 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, and a RAM (random access memory) that expands the program. A configuration may be adopted in which a storage device (recording medium) such as a memory for storing the program and various data is provided. In this case, an object of the present invention is a recording medium in which a program code (execution format program, intermediate code program, source program) of a control program of the image processing apparatus 10 which is software for realizing the functions described above is recorded so as to be readable by a computer. Is supplied to the image processing apparatus 10, and the computer (or CPU or MPU) reads and executes the program code recorded on the recording medium.

Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks / hard disks, and disks including optical disks such as CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

Alternatively, the image processing apparatus 10 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

In addition, each circuit (each block) of the image processing apparatus 10 may be realized using software, may be configured by hardware logic, and is a hardware that performs a part of the processing. Hardware and arithmetic means for executing software for performing control of the hardware and remaining processing may be combined.

As described above, the image processing apparatus of the present invention includes an upscaling processing unit for upscaling the resolution of RGB input image data to n times higher resolution, and displays the upscaled image data on the display unit. In this image processing apparatus, one pixel before upscaling corresponds to n divided pixels after upscaling, and each divided pixel includes a plurality of subpixels corresponding to RGB. A redistribution processing unit for redistributing gradation values assigned to a plurality of sub-pixels corresponding to the pixels, which are upscaled by the upscaling processing unit, with respect to the input image data corresponding to the pixels; And the redistribution processing unit assigns each sub-pixel to each sub-pixel when the n sub-pixels after the upscaling are regarded as one pixel. The gradation value is redistributed among the sub-pixels in the divided pixel, and the gradation value assigned to each sub-pixel is redistributed among the sub-pixels in the pixel for each RGB. It is characterized by doing.

In the above configuration, the gradation values assigned to the sub-pixels corresponding to RGB that have been upscaled are redistributed among the sub-pixels in the divided pixels, and re-distributed between the sub-pixels in the pixel for each RGB. Distribute. Therefore, for example, before and after redistribution, the luminance of one divided pixel and the chromaticity of one entire pixel do not change, and each subpixel of each RGB of one whole pixel (in one pixel) The luminance difference can be increased between sub-pixels of the same color. Thereby, the viewing angle can be improved while obtaining a high-definition image by the upscaling process. In the above configuration, since the viewing angle can be improved by distributing the gradation value among the sub-pixels, there is no need to newly divide the pixel to improve the viewing angle, and the panel transmittance is reduced and writing to the pixel is performed. There is no shortage of time.

In this image processing apparatus, the redistribution processing unit is configured such that, in each pixel, a luminance difference between subpixels of the same color after redistribution by the redistribution processing unit is the same color after upscaling by the upscaling processing unit. The redistribution may be performed so as to be larger than the luminance difference between the sub-pixels.

According to the above configuration, the number of pixels (sub-pixels) increases due to upscaling, and the luminance difference between the sub-pixels increases, so that the viewing angle can be improved.

In the image processing apparatus, the redistribution processing unit has the same luminance in one divided pixel after the upscaling by the upscaling processing unit and the luminance in the divided pixel after the redistribution by the redistribution processing unit. In the divided pixel, the gradation value assigned to each sub-pixel is redistributed among the sub-pixels in the divided pixel, and the color in one pixel after the up-scale by the up-scale processing unit In the pixel, the gradation value assigned to each sub-pixel is determined for each RGB so that the degree and the chromaticity in the pixel after redistribution by the redistribution processing unit are equal to each other. A configuration in which redistribution is performed between sub-pixels may be employed.

According to the above configuration, the luminance difference between the sub-pixels in the divided pixel can be increased without changing the luminance of the entire divided pixel and the chromaticity of the entire pixel before and after redistribution. it can. Therefore, the viewing angle can be improved without causing deterioration in display quality.

In the present image processing device, the redistribution processing unit is configured so that each of the divided pixels has a center of luminance at one divided pixel after redistribution by the redistribution processing unit. The gradation value assigned to the sub-pixel is redistributed among the sub-pixels in the divided pixel, and the center of chromaticity in one pixel after redistribution by the redistribution processing unit is set to the center of the pixel. In the pixel, the gradation value assigned to each sub-pixel may be redistributed among the sub-pixels in the pixel for each RGB.

This makes it difficult for the resolution and chromaticity of the appearance to change, so that the reliability can be improved without degrading the display quality.

As described above, the display device of the present invention includes the image processing device and a display unit that displays image data upscaled by the image processing device.

As described above, the image processing method of the present invention includes an upscaling step for upscaling the resolution of RGB input image data to n times higher resolution, and displays the upscaled image data on the display unit. In the image processing method, one pixel before upscaling corresponds to n divided pixels after upscaling, and each divided pixel includes a plurality of subpixels corresponding to RGB, and one pixel Re-distribution processing step of re-distributing the gradation values assigned to a plurality of sub-pixels corresponding to the pixel by up-scaling the input image data corresponding to the pixel, A display step of displaying image data on the display unit based on the gradation values redistributed by the redistribution processing step, In the distribution processing step, when the n divided pixels after the upscaling are regarded as one pixel, the gradation value assigned to each sub pixel is redistributed among the sub pixels in the divided pixel in each divided pixel. In addition, in each pixel, the gradation value assigned to each sub-pixel is redistributed among the sub-pixels in the pixel for each RGB.

In this image processing method, the redistribution processing step is represented by the luminance represented by one divided pixel after upscaling by the upscaling processing step and the divided pixel after redistribution by the redistribution processing step. In the divided pixel, the gradation value assigned to each sub-pixel is redistributed among the sub-pixels so that the luminance is equal to each other, and one after the up-scaling in the up-scaling processing step is performed. The gradation value assigned to each sub-pixel in the pixel so that the chromaticity represented by the pixel and the chromaticity represented by the pixel after redistribution in the redistribution processing step are equal to each other Can be redistributed among the sub-pixels for each RGB.

According to the above method, the luminance difference between the RGB sub-pixels of the entire pixel without changing the luminance of the entire divided pixel and the chromaticity of the entire pixel before and after redistribution. Can be increased. Therefore, the viewing angle can be improved without causing deterioration in display quality.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope indicated in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

The present invention can be applied to an image processing apparatus and an image processing method that upscale the resolution of input image data to a high resolution.

1 Display device 2 Liquid crystal display panel (display unit)
10 Image Processing Device 11 Upscale Circuit (Upscale Processing Unit)
12 Redistribution circuit (Redistribution processing unit)
13 Liquid crystal drive circuit 21 Pixel 22 (before up-scaling) Pixel P1, P2, P3, P4 (after up-scaling) Divided pixels R1, R2, R3, R4 Sub-pixel (R-sub-pixel)
G1, G2, RG, G4 Subpixel (G subpixel)
B1, B2, B3, B4 Subpixel (B subpixel)

Claims

An image processing apparatus comprising an upscaling processing unit for upscaling the resolution of RGB input image data to n times higher resolution, and displaying the upscaled image data on a display unit,
One pixel before upscaling corresponds to n divided pixels after upscaling, and each divided pixel is composed of a plurality of subpixels corresponding to RGB,
Redistribution processing for redistributing gradation values assigned to a plurality of sub-pixels corresponding to a plurality of sub-pixels upscaled by the upscaling processing unit for input image data corresponding to one pixel. Part
When the redistribution processing unit regards the n divided pixels after the upscaling as one pixel,
In each divided pixel, the gradation value assigned to each sub-pixel is redistributed among the sub-pixels in the divided pixel, and
An image processing apparatus characterized in that, in each pixel, the gradation value assigned to each sub-pixel is redistributed among the sub-pixels in the pixel for each RGB.
The redistribution processing unit
In each pixel, the luminance difference between subpixels of the same color after redistribution by the redistribution processing unit is larger than the luminance difference between subpixels of the same color after upscaling by the upscale processing unit. The image processing apparatus according to claim 1, wherein the redistribution is performed.
The redistribution processing unit
In the divided pixel, each sub-pixel is assigned to each sub-pixel so that the luminance in one divided pixel after upscaling by the upscale processing unit and the luminance in the divided pixel after redistribution by the redistribution processing unit are equal to each other. Redistributing the assigned tone values among the sub-pixels in the divided pixels;
In the pixel, the chromaticity in one pixel after upscaling by the upscaling processing unit and the chromaticity in the pixel after redistribution by the redistribution processing unit are allocated to each sub-pixel in the pixel. The image processing apparatus according to claim 1, wherein the gradation value is redistributed among sub-pixels in a pixel for each RGB.
The redistribution processing unit
In the divided pixel, the gradation value assigned to each sub-pixel is divided so that the luminance center in one divided pixel after redistribution by the redistribution processing unit is located at the center of the divided pixel. Redistribute between the sub-pixels in the pixel,
In the pixel, the gradation value assigned to each sub-pixel is determined for each RGB so that the center of chromaticity in one pixel after redistribution by the redistribution processing unit is located at the center of the pixel. The image processing apparatus according to any one of claims 1 to 3, wherein redistribution is performed among sub-pixels in a pixel.
The image processing apparatus according to any one of claims 1 to 4,
And a display unit for displaying the image data upscaled by the image processing apparatus.
An image processing method including an upscaling step for upscaling the resolution of RGB input image data to n times higher resolution, and displaying the upscaled image data on a display unit,
One pixel before upscaling corresponds to n divided pixels after upscaling, and each divided pixel is composed of a plurality of subpixels corresponding to RGB,
Redistribution processing step of re-distributing gradation values assigned to a plurality of sub-pixels corresponding to the pixel after re-scaling the input image data corresponding to one pixel by the up-scaling processing step. When,
A display step of displaying image data on the display unit based on the gradation values redistributed by the redistribution processing step,
In the redistribution processing step, when n divided pixels after upscaling are regarded as one pixel,
In each divided pixel, the gradation value assigned to each sub-pixel is redistributed among the sub-pixels in the divided pixel,
An image processing method characterized in that, in each pixel, the gradation value assigned to each sub-pixel is redistributed among sub-pixels in the pixel for each RGB.
In the redistribution processing step,
The divided pixels so that the luminance represented by one divided pixel after upscaling by the upscaling processing step and the luminance represented by the divided pixels after redistribution by the redistribution processing step are equal to each other. And redistributing the gradation value assigned to each sub-pixel among the sub-pixels,
In the pixel, the chromaticity represented by one pixel after upscaling by the upscaling processing step and the chromaticity represented by the pixel after redistribution by the redistribution processing step are equal to each other. The image processing method according to claim 6, wherein the gradation value assigned to each sub-pixel is redistributed among the sub-pixels for each RGB.
A program for operating a computer as the image processing apparatus according to any one of claims 1 to 4, wherein the computer functions as each unit of the image processing apparatus.
A computer-readable recording medium on which the program according to claim 8 is recorded.