CN109410874B

CN109410874B - Method and device for converting three-color data into four-color data

Info

Publication number: CN109410874B
Application number: CN201811543363.4A
Authority: CN
Inventors: 黄北洲
Original assignee: HKC Co Ltd
Current assignee: HKC Co Ltd
Priority date: 2018-12-17
Filing date: 2018-12-17
Publication date: 2021-04-23
Anticipated expiration: 2038-12-17
Also published as: CN109410874A

Abstract

The application relates to a method and a device for converting three-color data into four-color data. In the conversion method, a gain value is determined according to a preset rule and a first stimulus value signal, a second stimulus value signal and a third stimulus value signal, gain processing is carried out by using the gain value, a normalized stimulus value signal of a white sub-pixel is determined according to the minimum value in the stimulus value signals after the gain processing, a tri-stimulus value signal of the white sub-pixel is determined by using the normalized stimulus value signal of the white sub-pixel, normalized stimulus value signals of red, green and blue sub-pixels are respectively determined according to the stimulus value signal after the gain processing and the tri-stimulus value signal of the white sub-pixel, so that the gain of the white sub-pixel is consistent with the gain of the pixel point, the influence of the white sub-pixel is eliminated from the normalized stimulus value signals of the red, green and blue sub-pixels, the difference of the projection brightness of the white sub-pixel in each direction is reduced while the penetration rate of light and the brightness of a picture are improved, improve the color cast condition of large visual angle.

Description

Method and device for converting three-color data into four-color data

Technical Field

The present application relates to the field of display, and in particular, to a method and an apparatus for converting three-color data into four-color data.

Background

In general, a liquid crystal display generates a color to be displayed by color mixing of three color light sources generated by a red sub-pixel, a green sub-pixel and a blue sub-pixel. The RGB light source is formed by absorbing non-RGB light wave band by absorbing light resistance material in RGB sub-pixels (red sub-pixel, green sub-pixel and blue sub-pixel), so that RGB sub-pixels generate corresponding RGB light source. For example, the red photoresist of the red sub-pixel absorbs visible light in a non-red wavelength range and transmits visible light corresponding to the red wavelength range, and similarly, the green photoresist of the green sub-pixel absorbs visible light in a non-green wavelength range and transmits visible light corresponding to the green wavelength range, and the blue photoresist of the blue sub-pixel absorbs visible light in a non-blue wavelength range and transmits visible light corresponding to the blue wavelength range. Therefore, it can be understood that only part of the visible light backlight light source mainly comprising white light passes through the red, green and blue sub-pixels.

With the improvement of the display resolution, after the current common 4K resolution display is developed to an 8K resolution display, the increase of the sub-pixels leads to the decrease of the aperture ratio of the corresponding pixels, the transmittance of the high resolution display is reduced, and the light utilization rate is reduced. Therefore, corresponding to the development of the 4-color sub-pixels, except for the original red, green and blue sub-pixels corresponding to mixed colors, the 4 th sub-pixel development adopts a sub-pixel technology with high penetration rate, so that the display can have high resolution and can also take into account the improvement of the penetration rate of the display, the light efficiency is improved, and the high-resolution display can also take into account the cost of a backlight framework. The currently developed and commercialized 4-color sub-pixel is a color-mixed color display device composed of a white sub-pixel, a red sub-pixel, a green sub-pixel and a blue sub-pixel, wherein the white sub-pixel does not need a photoresist absorption material for absorbing visible light energy, so that the light penetration rate in the display device can be improved, and the light utilization efficiency can be further improved.

However, the currently commercially available 4-color sub-pixel product is an IPS (In-Plane Switching) liquid crystal display, which has the same transmittance at all wavelengths In the normal viewing angle and In the wide viewing angle and has the transmittance ratio at all wavelengths, so that the same color performance can be maintained In the optical characteristics of both the normal viewing angle and the wide viewing angle, and no color difference occurs. The VA (Vertical Alignment ) lcd has the characteristics of high throughput and low production cost compared to the IPS lcd, but because the characteristics of the full-wavelength transmittance of visible light at the normal viewing angle and the large viewing angle of the VA lcd are different, the optical characteristics of the VA lcd at the large viewing angle cannot be maintained the same as the colors of the VA lcd at the normal viewing angle, and the VA lcd has the problems of large viewing angle color shift defect, color distortion, and the like.

Disclosure of Invention

Based on this, the application provides a method and a device for converting three-color data into four-color data, so as to solve the problems of low light penetration rate, large viewing angle color cast and color distortion.

The application provides a method for converting three-color data into four-color data, which comprises the following steps:

determining a first stimulus value signal which has the largest influence on mixed color in the tristimulus value signals of the red sub-pixels in each pixel point, a second stimulus value signal which has the largest influence on the mixed color in the tristimulus value signals of the green sub-pixels, and a third stimulus value signal which has the largest influence on the mixed color in the tristimulus value signals of the blue sub-pixels;

respectively determining a gain value corresponding to each pixel point according to a preset rule and the first stimulus value signal, the second stimulus value signal and the third stimulus value signal corresponding to each pixel point;

performing gain processing on the first stimulus value signal, the second stimulus value signal and the third stimulus value signal corresponding to each pixel point by using a gain value in each pixel point, and determining a normalized stimulus value signal of a white sub-pixel according to a minimum value among the first stimulus value signal after the gain processing, the second stimulus value signal after the gain processing and the third stimulus value signal after the gain processing;

calculating a tristimulus value signal corresponding to the white sub-pixel according to the normalized stimulus value signal of the white sub-pixel; and

calculating a difference value between the first stimulus value signal after the gain processing and an X stimulus value signal having a large relationship with a red stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus signal of the red sub-pixel, calculating a difference value between the second stimulus value signal after the gain processing and a Y stimulus value signal having a large relationship with a green stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the green sub-pixel, and calculating a difference value between the third stimulus value signal after the gain processing and a Z stimulus value signal having a large relationship with a blue stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the blue sub-pixel.

In one embodiment, the determining, according to a preset rule and the first stimulus value signal, the second stimulus value signal, and the third stimulus value signal corresponding to each pixel point, a gain value corresponding to each pixel point respectively includes:

determining a maximum value and a minimum value in the first stimulation value signal, the second stimulation value signal and the third stimulation value signal corresponding to the pixel point;

judging whether the maximum value is less than 2 times of the minimum value;

if yes, the gain value of the pixel point is 2;

otherwise, calculating the color mixing saturation corresponding to the pixel point in the three primary color gamut according to the first stimulus value signal, the second stimulus value signal and the third stimulus value signal;

calculating the color mixing saturation corresponding to the pixel point in the four primary color gamut according to the color mixing saturation corresponding to the pixel point in the three primary color gamut and a preset mapping relation; and

and determining the gain value of the pixel point according to the color mixing saturation corresponding to the pixel point in the four primary color gamut.

In one embodiment, the calculating the color mixture saturation corresponding to the pixel point in the four-primary-color gamut according to the color mixture saturation corresponding to the pixel point in the three-primary-color gamut and a preset mapping relationship includes:

wherein S is the color mixture saturation corresponding to the pixel point in the three primary color gamut, S' is the color mixture saturation corresponding to the pixel point in the four primary color gamut, the K adjustment factor and the R_XIs the first stimulus value signal, the G_YIs the second stimulus value signal, B_ZIs the third stimulus value signal.

In one embodiment, the calculating the gain value of the pixel point according to the color mixture saturation in the three primary color gamut and a preset mapping relationship includes:

S′(S)＝a×S⁴+b×S³+c×S²+d×S+e

wherein S is the color mixture saturation corresponding to the pixel point in the three primary color gamut, S' is the color mixture saturation corresponding to the pixel point in the four primary color gamut, and a, b, c, d and e are constants.

S′(H,S)＝a(H)×S⁴+b(H)×S³+c(H)×S²+d(H)×S+e(H)

wherein S is the color mixing saturation corresponding to the pixel point in the three primary color gamut, S' is the color mixing saturation corresponding to the pixel point in the four primary color gamut, and a (H), b (H), c (H), d (H) and e (H) are all functions based on the hue corresponding to the pixel point.

In one embodiment, the switching method further includes:

judging whether the gain value is in an interval [1,2 ];

when the gain value is smaller than 1, the gain value takes a value of 1; and

and when the gain value is larger than 2, the gain value takes 2.

In one embodiment, the determining the first stimulus value signal having the greatest influence on mixed color in the tristimulus value signals of the red sub-pixels, the second stimulus value signal having the greatest influence on mixed color in the tristimulus value signals of the green sub-pixels, and the third stimulus value signal having the greatest influence on mixed color in the tristimulus value signals of the blue sub-pixels includes:

calculating the overlapping of a stimulus function X, a stimulus function Y and a stimulus function Z with the penetration spectrum of the red sub-pixel respectively, wherein the overlapping part of the penetration spectrum of the red sub-pixel and the stimulus function X is maximum, and determining a stimulus value signal R in the red sub-pixel tri-stimulus value signal according to the calculation result_XThe stimulus value signal with the maximum color mixing in the red sub-pixel tri-stimulus value signal R_XAs the first stimulus value signal;

calculating the overlapping of a stimulus function X, a stimulus function Y and a stimulus function Z with the penetration spectrum of the green sub-pixel respectively, wherein the overlapping part of the penetration spectrum of the green sub-pixel and the stimulus function Y is the largest, and determining a stimulus value signal G in the tri-stimulus value signal of the green sub-pixel according to the calculation result_YThe stimulus value signal with the maximum color mixing color in the green sub-pixel tri-stimulus value signals, and the stimulus value signal G_YAs the second stimulus value signal; and

calculating the overlapping of a stimulus function X, a stimulus function Y and a stimulus function Z with the penetration spectrum of the blue sub-pixel respectively, wherein the overlapping part of the penetration spectrum of the blue sub-pixel and the stimulus function Z is maximum, and determining a stimulus value signal B in the tri-stimulus value signal of the blue sub-pixel according to the calculation result_ZThe stimulus value signal with the maximum color mixing color in the blue sub-pixel tri-stimulus value signals is selected, and the stimulus value signal B is selected_ZAs the third stimulus value signal.

In one embodiment, the switching method further includes:

calculating and outputting an output gray-scale value of the white sub-pixel according to the normalized stimulus value signal of the white sub-pixel;

calculating and outputting an output gray-scale value of the red sub-pixel according to the normalized stimulus value signal of the red sub-pixel;

calculating and outputting an output gray-scale value of the green sub-pixel according to the normalized stimulus value signal of the green sub-pixel; and

and calculating and outputting an output gray-scale value of the blue sub-pixel according to the normalized stimulus value signal of the blue sub-pixel.

Based on the same inventive concept, the present application further provides another method for converting three-color data into four-color data, comprising:

determining a first stimulus value signal which has the largest influence on mixed color in the tristimulus value signals of the red sub-pixel in the nth pixel point, a second stimulus value signal which has the largest influence on the mixed color in the tristimulus value signals of the green sub-pixel, and a third stimulus value signal which has the largest influence on the mixed color in the tristimulus value signals of the blue sub-pixel;

determining a gain value of the nth pixel point according to a preset rule and the first stimulus value signal, the second stimulus value signal and the third stimulus value signal corresponding to the nth pixel point;

performing gain processing on the first stimulus value signal, the second stimulus value signal and the third stimulus value signal by using a gain value in the nth pixel point, and determining a normalized stimulus value signal of the white sub-pixel according to a minimum value of the first stimulus value signal after the gain processing, the second stimulus value signal after the gain processing and the third stimulus value signal after the gain processing;

calculating a difference value between the first stimulus value signal after the gain processing and an X stimulus value signal having a large relationship with a red stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus signal of the red sub-pixel, calculating a difference value between the second stimulus value signal after the gain processing and a Y stimulus value signal having a large relationship with a green stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the green sub-pixel, and calculating a difference value between the third stimulus value signal after the gain processing and a Z stimulus value signal having a large relationship with a blue stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the blue sub-pixel. .

Based on the same inventive concept, the present application further provides a device for converting three-color data into four-color data, the device comprising:

a memory for storing computer instructions; and

and the at least one processor is connected with the memory in a communication manner and used for receiving the computer instructions in the memory and executing the conversion method for converting the three-color data into the four-color data according to the computer instructions.

In summary, the present application provides a method and an apparatus for converting three-color data into four-color data. In the conversion method, according to a preset rule and the first stimulus value signal, the second stimulus value signal and the third stimulus value signal corresponding to each pixel point, a gain value corresponding to each pixel point is respectively determined; then, gain processing is carried out on the first stimulus value signal, the second stimulus value signal and the third stimulus value signal corresponding to each pixel point by using a gain value in each pixel point, and a normalized stimulus value signal of a white sub-pixel is determined according to the minimum value of the first stimulus value signal after the gain processing, the second stimulus value signal after the gain processing and the third stimulus value signal after the gain processing; secondly, calculating a tristimulus value signal corresponding to the white sub-pixel according to the normalized stimulus value signal of the white sub-pixel; then, a difference value between the first stimulus value signal after the gain processing and an X stimulus value signal having a large relationship with a red stimulus value signal among the tristimulus value signals of the white sub-pixel is calculated as a normalized stimulus value signal of the red sub-pixel, a difference value between the second stimulus value signal after the gain processing and a Y stimulus value signal having a large relationship with a green stimulus value signal among the tristimulus value signals of the white sub-pixel is calculated as a normalized stimulus value signal of the green sub-pixel, and a difference value between the third stimulus value signal after the gain processing and a Z stimulus value signal having a large relationship with a blue stimulus value signal among the tristimulus value signals of the white sub-pixel is calculated as a normalized stimulus value signal of the blue sub-pixel. In the conversion method provided by the application, according to a preset rule and the first stimulus value signal, the second stimulus value signal and the third stimulus value signal corresponding to each pixel point, a gain value corresponding to each pixel point is respectively determined, then gain processing is performed on the first stimulus value signal, the second stimulus value signal and the third stimulus value signal corresponding to the pixel point by using the gain value, and a normalized stimulus value signal of a white sub-pixel is determined according to a minimum value in the first stimulus value signal after gain processing, the second stimulus value signal after gain processing and the third stimulus value signal after gain processing, so that the normalized stimulus value signal of the white sub-pixel can be adjusted according to the gain value of the pixel point, so that a gray level value of the white sub-pixel can be obtained by subsequent calculation according to the normalized stimulus value signal of the white sub-pixel, the gain of the white sub-pixel point is consistent with the gain of the pixel point, and the influence of the white sub-pixel is eliminated by the normalized stimulus value signals of the red sub-pixel, the green sub-pixel and the blue sub-pixel, so that the scheme not only improves the light penetration rate and the picture quality, but also can reduce the difference of the projection brightness of the white sub-pixel in each direction, thereby improving the condition of large visual angle color cast.

Drawings

FIG. 1 is a diagram showing the proportional characteristics of stimulus values RY, GY, BY and luminance values of an IPS LCD;

FIG. 2 is a schematic flow chart of a method for converting RGB data into WRGB data in an IPS type LCD;

FIG. 3 is a diagram showing the proportional characteristics of stimulus values RY, GY, BY and luminance values of a VA mode LCD;

FIG. 4 is a graph showing the proportional characteristics of the stimulus values RX, GY and BZ to the luminance values in a VA mode LCD;

fig. 5 is a schematic flowchart illustrating a method for converting three-color data into four-color data according to an embodiment of the present disclosure;

fig. 6 is a schematic flowchart illustrating a method for converting three-color data into four-color data based on an adjustment factor according to an embodiment of the present disclosure;

fig. 7 is a graph illustrating a relationship between saturation of a pixel in a three-primary color gamut and saturation of a pixel in a four-primary color gamut according to an embodiment of the present disclosure;

fig. 8 is a graph illustrating a relationship between saturation of a pixel in a three-primary color gamut and saturation of a pixel in a four-primary color gamut according to another embodiment of the present disclosure;

fig. 9 is a schematic flowchart of a method for converting three-color data into four-color data based on a polynomial function according to an embodiment of the present application;

fig. 10 is a graph illustrating a relationship between saturation of a pixel in a three-primary color gamut and saturation of a pixel in a four-primary color gamut according to an embodiment of the present disclosure;

fig. 11 is a flowchart illustrating a method for converting three-color data into four-color data based on a polynomial function and pixel hues according to an embodiment of the present application;

FIG. 12 is a CIE HSV color model;

fig. 13 is a flowchart illustrating another method for converting three-color data into four-color data according to an embodiment of the present disclosure.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present application more comprehensible, embodiments accompanying the present application are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. This application is capable of embodiments in many different forms than those described herein and those skilled in the art will be able to make similar modifications without departing from the spirit of the application and it is therefore not intended to be limited to the embodiments disclosed below.

The optical characteristics of the red, green and blue sub-pixels of the VA type LCD are different compared with the IPS LCD. The variation of the red, green and blue sub-pixel signals of the IPS display with respect to the optical luminance stimulus value varies as shown in fig. 1, the optical luminance stimulus value signals RY, GY and BY respectively corresponding to the red, green and blue sub-pixels vary the same, RY is taken as the stimulus value signal having the greatest association with the red sub-pixel, GY is taken as the stimulus value signal having the greatest association with the green sub-pixel, and BY is taken as the stimulus value signal having the greatest association with the blue sub-pixel.

Referring to fig. 2, in order to improve the picture quality, the sub-pixels are gain-processed BY using a fixed gain value, and the minimum value of RY ', GY' and BY 'after the gain processing is used as the normalized stimulus value signal WY of the white sub-pixel, the difference value between RY' and WY is used as the normalized stimulus value signal of the red sub-pixel, the difference value between GY 'and WY is used as the normalized stimulus value signal of the green sub-pixel, and the difference value between BY' and WY is used as the normalized stimulus value signal of the red sub-pixel, and then the corresponding gray level value is calculated and outputted according to the normalized stimulus value signal of each sub-pixel.

However, the variation of the red, green and blue sub-pixel signals of the VA lcd corresponding to the optical luminance stimulation value signals RY, GY and BY is as shown in fig. 3, and the variation of the red, green and blue sub-pixel signals corresponding to the optical luminance stimulation value signals is different, i.e. RY ≠ GY ≠ BY.

In the VA-type lcd, the red, green and blue sub-pixels mainly have the largest influence on the color mixture of RX stimulus values in the tri-stimulus value signals (RX, RY, RZ) of the red sub-pixel, GY stimulus values in the tri-stimulus value signals (GX, GY, GZ) of the green sub-pixel, and BZ stimulus values in the tri-stimulus value signals (BX, BY, BZ) of the blue sub-pixel. Referring to fig. 4, the proportional weight of the variation of the stimulus value signals RX, GY and BZ of the red, green and blue sub-pixels in fig. 4 (RX ≈ GY ≈ BZ) is closer to that of the variation of the stimulus value signals RY, GY and BY of the red, green and blue sub-pixels in fig. 3 (RY ≠ GY ≠ BY), and the determined stimulus value signals of the white pixels based on RX, GY and BZ can reduce the luminance difference of the pixel points in all directions to reduce the large viewing angle color difference.

Referring to fig. 5, an embodiment of the present application provides a method for converting three-color data into four-color data, including:

step S110, determining a first stimulus value signal having the largest influence on mixed color in the tristimulus value signals of the red sub-pixels in each pixel point, a second stimulus value signal having the largest influence on mixed color in the tristimulus value signals of the green sub-pixels, and a third stimulus value signal having the largest influence on mixed color in the tristimulus value signals of the blue sub-pixels;

step S120, respectively determining a gain value corresponding to each pixel point according to a preset rule and the first stimulus value signal, the second stimulus value signal and the third stimulus value signal corresponding to each pixel point;

step S130, performing gain processing on the first stimulus value signal, the second stimulus value signal and the third stimulus value signal corresponding to each pixel point by using a gain value in each pixel point, and determining a normalized stimulus value signal of a white sub-pixel according to a minimum value among the first stimulus value signal after the gain processing, the second stimulus value signal after the gain processing and the third stimulus value signal after the gain processing;

step S140, calculating a tristimulus value signal corresponding to the white sub-pixel according to the normalized stimulus value signal of the white sub-pixel;

step S150, calculating a difference between the first stimulus value signal after the gain processing and an X stimulus value signal having a large relationship with a red stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus signal of the red sub-pixel, calculating a difference between the second stimulus value signal after the gain processing and a Y stimulus value signal having a large relationship with a green stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the green sub-pixel, and calculating a difference between the third stimulus value signal after the gain processing and a Z stimulus value signal having a large relationship with a blue stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the blue sub-pixel.

In this embodiment, the three-color data refers to RGB data, the four-color data refers to WRGB data, the three-color gamut refers to an RGB gamut, and the four-color gamut refers to a WRGB gamut.

It can be understood that in the conversion method provided by the present application, a gain value corresponding to each pixel point is respectively determined according to a preset rule and the first stimulus value signal, the second stimulus value signal, and the third stimulus value signal corresponding to each pixel point, then gain processing is performed on the first stimulus value signal, the second stimulus value signal, and the third stimulus value signal corresponding to the pixel point by using the gain value, and a normalized stimulus value signal of a white sub-pixel is determined according to a minimum value of the first stimulus value signal after gain processing, the second stimulus value signal after gain processing, and the third stimulus value signal after gain processing, so that the normalized stimulus value signal of the white sub-pixel can be adjusted according to the gain value of the pixel point, so that a gray level value of the white sub-pixel can be subsequently calculated according to the normalized stimulus value signal of the white sub-pixel, the gain of the white sub-pixel point is consistent with the gain of the pixel point, and the influence of the white sub-pixel is eliminated by the normalized stimulus value signals of the red sub-pixel, the green sub-pixel and the blue sub-pixel, so that the scheme not only improves the light penetration rate and the picture quality, but also can reduce the difference of the projection brightness of the white sub-pixel in each direction, thereby improving the condition of large visual angle color cast.

It is understood that the more the white sub-pixel occupies, the greater the influence on the decrease in color vividness. Conversely, the smaller the proportion of the white sub-pixel, the less the influence on the decrease in the color vividness, but the lower the overall image quality luminance. Therefore, it is necessary to control the ratio of the white sub-pixels to adjust the ratio of the white sub-pixels so that the image with higher color vividness in the three-primary color gamut can have the same better vividness in the four-primary color gamut when the color vividness varies with the input signal. In this embodiment, each pixel is gained by a dynamic gain value to control the proportion of the white sub-pixels, thereby improving the picture quality.

In one embodiment, referring to fig. 6, the determining the gain value corresponding to each pixel point according to a preset rule and the first stimulus value signal, the second stimulus value signal, and the third stimulus value signal corresponding to each pixel point respectively includes:

judging whether the maximum value is less than 2 times of the minimum value;

if yes, the gain value of the pixel point is 2;

In this embodiment, the tristimulus value signal of the red sub-pixel:

wherein R is the gray level value of the red sub-pixel, and R is_XThe R is_YAnd said R_ZIs the tristimulus value signal of the red sub-pixel, the

The above-mentioned

And said

Are respectively the R_XThe R is_YAnd said R_ZThe corresponding power function.

Tristimulus value signals of the green sub-pixel:

wherein G is the gray scale value of the green sub-pixel, and G is the gray scale value of the green sub-pixel_XThe G_YAnd said G_ZIs the tristimulus value signal of the green sub-pixel, the

The above-mentioned

And said

Respectively is the G_XThe G_YAnd said G_ZThe corresponding power function.

The tristimulus value signal of the blue sub-pixel:

wherein B is the gray scale value of the blue sub-pixel, and B is the gray scale value of the blue sub-pixel_XThe B_YAnd said B_ZIs the tristimulus value signal of the blue sub-pixel, the

The above-mentioned

And said

Are respectively the B_XThe B_YAnd said B_ZThe corresponding power function.

Stimulus value signal R in the red sub-pixel tristimulus value signal_XThe stimulus value signal with the maximum color mixing color in the red sub-pixel tri-stimulus value signals is the stimulus value signal R_X。

Stimulus value signal G in the green sub-pixel tristimulus value signal_YThe stimulus value signal with the maximum color mixture color in the green sub-pixel tri-stimulus value signals is the stimulus value signal G_Y。

Stimulus value signal B in the blue sub-pixel tristimulus value signal_ZThe stimulus value signal with the maximum color mixture color in the blue sub-pixel tri-stimulus value signals is the stimulus value signal B_Z。

When the stimulus value signal R_X、G_YAnd B_ZSatisfies Max (R)_X，G_Y，B_Z)-2×Min(R_X，G_Y，B_Z) When the color is less than 0, the color mixing is closer to unsaturated neutral color, and the white sub-pixel is based on the stimulus value R input by the red sub-pixel and the green sub-pixel_X，G_YAnd B_ZThe Gain value is dynamically adjusted to 2, wherein the limit of the Gain value cannot exceed 2 because the sum of the transmittances of the red, green and blue three-color sub-pixels in the preferred four sub-pixels is equal to the transmittance of the white sub-pixel. The reason why the limit of Gain value cannot exceed 2 is that the stimulus values of the three-color sub-pixels of red, green and blue plus the stimulus value of the white sub-pixel are only 2 times as large as the stimulus values of the three-color sub-pixels of red, green and blue at the maximum.

When the stimulus value signal R_X、G_YAnd B_ZSatisfies Max (R)_X，G_Y，B_Z)-2×Min(R_X，G_Y，B_Z) When the color is more than 0, the mixed color is closer to the saturated color, the output proportion of the white sub-pixel is dynamically adjusted, the influence of the white sub-pixel on the saturated color is reduced, and the white sub-pixel is based on the stimulus value R input by the red, green and blue sub-pixels_X、G_YAnd B_ZThe Gain value Gain is dynamically adjusted so that Gain is 1/S '(S) and S' (S) indicates the color purity S (Max (R)_X，G_Y，B_Z)-Min(R_X，G_Y，B_Z))/Max(R_X，G_Y，B_Z) The function of (1) is that the Gain value is dynamically adjusted between 1 and 2, the Gain value is reduced along with the improvement of the coloring purity value, the minimum Gain value is 1, the reduction of the coloring purity value represents that the color mixing is closer to unsaturated neutral color, and the white sub-pixel is based on the stimulus value R input by the red, green and blue sub-pixels_X、G_YAnd B_ZAnd dynamically adjusting the Gain value to increase the Gain, wherein the maximum Gain value Gain takes 2.

S 'is dynamically adjusted according to S, and the following figure 7 illustrates the relationship between S' and S, namely the stimulus value signal R input by the red, green and blue sub-pixels_X、G_YAnd B_ZCalculating color purity S ═ (Max (R)_X，G_Y，B_Z)-Min(R_X，G_Y，B_Z))/Max(R_X，G_Y，B_Z) Wherein the color purity S satisfies 0 ≦ S ≦ 1, and if it is desired that the white, red, green, and blue subpixels output stimulus value signals R relative to the red, green, and blue subpixels input_X、G_YAnd B_ZIf the color purity is higher, the Gain value is dynamically adjusted to improve the Gain output of the color purity S.

In this embodiment, the adjustment factor has a value range of 0 to 1. When S is more than K, making S' equal to 1; when S is less than K, the design requirement

When the saturation S > K, S' is 1, there is a lower dynamic Gain value, and Gain is 1, so that the output of the W sub-pixel is reduced to increase the color saturation.

In this embodiment, K is 0.5, that is, when the saturation is higher than 0.5, the dynamic Gain value Gain of the white sub-pixel is minimum, and the larger the K value is, the higher the saturation is, and the output of the pixel with four primary colors of white, red, green and blue after the three primary colors of red, green and blue are combined and converted can be presented with higher color purity.

Therefore, according to fig. 7, the relationship between S and S ', when S > 0.5, S' is 1, and the stimulus value signal R input by the red, green and blue three sub-pixels is required_X、G_YAnd B_ZWhen the saturation S > 0.5, S' is 1. When S < 0.5, S ' is 2S 2 (Max (RX, GY, BZ) -Min (RX, GY, BZ)/Max (RX, GY, BZ)), and S ' satisfies 0. ltoreq. S ' 1.

In one embodiment, please refer to fig. 8 and 9, the calculating the gain value of the pixel point according to the color mixture saturation in the three primary color gamut and the preset mapping relationship includes:

S′(S)＝a×S⁴+b×S³+c×S²+d×S+e

In this embodiment, the polynomial function relationship between S and S' is the inputStimulus value signal R input by red, green and blue three sub-pixels_X、G_YAnd B_ZAnd calculating the color purity S, wherein the value range of the color purity S is 0-1. If it is desired that the output of the white, red, green, and blue four sub-pixels has a higher color purity, the Gain output of the color purity S must be increased by dynamically adjusting the Gain value.

In one embodiment, referring to fig. 10 and fig. 11, the calculating the gain value of the pixel point according to the color mixture saturation in the three primary color gamut and the preset mapping relationship includes:

S′(H，S)＝a(H)×S⁴+b(H)×S³+c(H)×S²+d(H)×S+e(H)

In this embodiment, the relation of the polynomial function between S and S' is the stimulus value signal R inputted into the red, green and blue sub-pixels_X、G_YAnd B_ZAnd calculating the color purity S, wherein the value range of the color purity S is 0-1. If it is desired that the output of the white, red, green, and blue sub-pixels has a higher color purity, the Gain value is dynamically adjusted to increase the Gain output of the color purity S.

The color saturation signal S 'is increased according to the range of hue H of each color, and the saturation of different hues is increased differently, as shown in S' (H) in FIG. 10₁S) and S' (H)₂，S)，H₁The range of H is 0-30 and 330-360 degree red range, H₂The range interval of the representative H is a green interval with H being 90-150 degrees, and it can be seen that when the values of H are different, the corresponding saturation degrees are different.

In one embodiment, the conversion method further includes:

judging whether the gain value is in an interval [1,2 ];

when the gain value is smaller than 1, the gain value takes a value of 1; and

and when the gain value is larger than 2, the gain value takes 2.

In one embodiment, the conversion method further includes:

calculating difference values of the first stimulus value signal after the gain processing, the second stimulus value signal after the gain processing and the third stimulus value signal after the gain processing and the normalized stimulus value signal of the white sub-pixel respectively;

and taking the difference value of the first stimulation value signal after gain processing and the normalized stimulation value signal of the white sub-pixel as the normalized stimulation value signal of the red sub-pixel, taking the difference value of the second stimulation value signal after gain processing and the normalized stimulation value signal of the white sub-pixel as the normalized stimulation value signal of the green sub-pixel, and taking the difference value of the third stimulation value signal after gain processing and the normalized stimulation value signal of the white sub-pixel as the normalized stimulation value signal of the blue sub-pixel.

It is understood that the gain-processed first stimulus value signal R 'in this embodiment'_X＝Gain×R_XThe gain-processed second stimulus value signal G'_Y＝Gain×G_YThe gain-processed third stimulus value signal B'_Z＝Gain×B_Z. Normalized stimulus value signal W of the white sub-pixel_Y＝Min(R′_X，G′_Y，B′_Z)，

In one embodiment, the calculating a tristimulus value signal corresponding to the white sub-pixel according to the normalized stimulus value signal of the white sub-pixel includes:

calculating the gray-scale value of the white sub-pixel according to the normalized stimulus value signal of the white sub-pixel; and

and carrying out normalization processing on the gray-scale value of the white sub-pixel, and determining the tristimulus value of the white sub-pixel.

In this embodiment, the normalized stimulus value signal W according to the white sub-pixel_YAnd calculating the gray-scale value W of the white sub-pixel, wherein the value range of W is 0-255. Then, calculating a stimulation value signal W with large correlation between the white sub-pixel and the red stimulation value signal according to the gray scale value W of the white sub-pixel_XAnd a stimulus value signal W having a large correlation with the blue stimulus value signal_Z。

Wherein the content of the first and second substances,

W＝W_Y ¹/γW_Y×255

wherein, the

And said

Respectively is the W_Y、W_XAnd W_ZThe corresponding power function.

It is understood that the color mixture color of the red, green, and blue subpixels in the RGB display mode is the same as or as close as possible to the color mixture color of the white, red, green, and blue subpixels in the WRGB display mode, i.e., R'_X＝R″_X+W_X，G′_Y＝G″_Y+W_Y，B′_Z＝B″_Z+W_ZThe effect of the tristimulus values of the white sub-pixel on the red, green and blue sub-pixels should be eliminated. Benefits described in this examplePost-processed first stimulus value signal R'_X＝Gain×R_XThe gain-processed second stimulus value signal G'_Y＝Gain×G_YThe gain-processed third stimulus value signal B'_Z＝Gain×B_ZNormalized stimulus value signal W of the white sub-pixel_Y＝Min(R′_X，G′_Y，B′_Z)。

In this embodiment, in the color gamut corresponding to the four-color data, the normalized stimulus value signal R ″ of the red sub-pixel_X＝R′_X-W_XNormalized stimulus value signal G' of the green sub-pixel_Y＝G′_Y-W_YNormalized stimulus value signal B' of the blue sub-pixel_Z＝B′_Z-W_Z. Therefore, the overlapping part of the white sub-pixel is eliminated in the red, green and blue sub-pixels, so that the color mixture color of the red sub-pixel, the green sub-pixel and the blue sub-pixel in the RGB display mode is the same as or close to the color mixture color of the white sub-pixel, the red sub-pixel, the green sub-pixel and the blue sub-pixel in the WRGB display mode. It should be noted that, when the normalized stimulus value signal of the red/green/blue sub-pixel is greater than or equal to 1, the normalized stimulus value signal of the red/green/blue sub-pixel takes a value of 1.

In one embodiment, the conversion method further includes:

In this embodiment, the output gray-scale values of the white sub-pixel, the red sub-pixel, the green sub-pixel, and the blue sub-pixel are respectively:

W_out＝W_Y ¹/γW_Y×255

R_out＝R″_X ¹/γR_X×255

G_out＝G″_Y ¹/γ_Y×255

B_out＝B″_Z ¹/γB_Z×255

wherein, the W_out、R_out、G_out、B_outAnd W_outOutput gray-scale values of the white sub-pixel, the red sub-pixel, the green sub-pixel, the blue sub-pixel and the white sub-pixel, respectively, the gamma W_YIs the said W_YThe corresponding power function.

In one embodiment, between determining the first, second and third stimulus value signals, the conversion method further comprises:

respectively inputting the gray-scale values of the red sub-pixel, the green sub-pixel and the blue sub-pixel;

and respectively determining a tristimulus value signal of the red sub-pixel, a tristimulus value signal of the green sub-pixel and a tristimulus value signal of the blue sub-pixel according to the gray-scale values of the red sub-pixel, the green sub-pixel and the blue sub-pixel.

Referring to fig. 12, in the present embodiment, the Hue and Saturation of the color corresponding to the pixel point are calculated by converting the input gray-scale Value R of the red sub-pixel, the input gray-scale Value G of the green sub-pixel, and the input gray-scale Value B of the blue sub-pixel into HSV (Hue, Saturation, and lightness) color models. Wherein, the gray-scale value R of the red sub-pixel, the gray-scale value G of the green sub-pixel and the gray-scale value B of the blue sub-pixel are 8-bit gray-scale digital signals of 0, 1, 255, and the brightness normalization signals of each gray-scale signal corresponding to the maximum gray-scale value 255 are R, G and B respectively, wherein, the brightness normalization signals of each gray-scale signal corresponding to the maximum gray-scale value 255 are R, G and B respectively, and the brightness normalization signals are R, G and B respectively

And

the gamma is_r、γ_gAnd gamma_bThe digital gray scale signal is converted into an exponential parameter of the luminance signal for a luminance gain gamma (gamma) signal. The algorithm for converting the gray-scale value R of the red sub-pixel, the gray-scale value G of the green sub-pixel and the gray-scale value B of the blue sub-pixel into the HSV color model is as follows:

where h is the value corresponding to hue and s is the value corresponding to saturation.

In one embodiment, the determining a first stimulus value signal having a largest influence on mixed color in the tristimulus value signals of the red sub-pixels, a second stimulus value signal having a largest influence on mixed color in the tristimulus value signals of the green sub-pixels, and a third stimulus value signal having a largest influence on mixed color in the tristimulus value signals of the blue sub-pixels includes:

calculating a stimulus function X, a stimulus function Y and a stimulus function Z respectively with theOverlapping of penetration spectrums of green sub-pixels, wherein the overlapping part of the penetration spectrums of the green sub-pixels and the stimulation function Y is maximum, and determining a stimulation value signal G in the green sub-pixel tri-stimulation value signals according to the calculation result_YThe stimulus value signal with the maximum color mixing color in the green sub-pixel tri-stimulus value signals, and the stimulus value signal G_YAs the second stimulus value signal; and

Based on the same inventive concept, the present application further provides another method for converting three-color data into four-color data, please refer to fig. 13, where the method includes:

step S210, determining a first stimulus value signal with the largest influence on mixed color in the tristimulus value signals of the red sub-pixel in the nth pixel point, a second stimulus value signal with the largest influence on mixed color in the tristimulus value signals of the green sub-pixel, and a third stimulus value signal with the largest influence on mixed color in the tristimulus value signals of the blue sub-pixel;

step S220, determining a gain value of the nth pixel point according to a preset rule and the first stimulus value signal, the second stimulus value signal, and the third stimulus value signal corresponding to the nth pixel point;

step S230, performing gain processing on the first stimulus value signal, the second stimulus value signal, and the third stimulus value signal by using the gain value in the nth pixel point, and determining a normalized stimulus value signal of the white sub-pixel according to a minimum value among the first stimulus value signal after the gain processing, the second stimulus value signal after the gain processing, and the third stimulus value signal after the gain processing;

step S240, calculating a tristimulus value signal corresponding to the white sub-pixel according to the normalized stimulus value signal of the white sub-pixel.

Step S250, calculating a difference between the first stimulus value signal after the gain processing and an X stimulus value signal having a large relationship with a red stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus signal of the red sub-pixel, calculating a difference between the second stimulus value signal after the gain processing and a Y stimulus value signal having a large relationship with a green stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the green sub-pixel, and calculating a difference between the third stimulus value signal after the gain processing and a Z stimulus value signal having a large relationship with a blue stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the blue sub-pixel.

judging whether the maximum value is less than 2 times of the minimum value;

if yes, the gain value of the pixel point is 2;

In one embodiment, in this embodiment, the tristimulus value signal of the red sub-pixel:

The above-mentioned

And said

Are respectively the R_XThe R is_YAnd said R_ZThe corresponding power function.

Tristimulus value signals of the green sub-pixel:

The above-mentioned

And said

Respectively is the G_XThe G_YAnd said G_ZThe corresponding power function.

The tristimulus value signal of the blue sub-pixel:

The above-mentioned

And said

Are respectively the B_XStation, stationB above_YAnd said B_ZThe corresponding power function.

In this embodiment, the value of the adjustment factor satisfies 0 < K < 1. When S is more than K, making S' equal to 1; when S is less than K, the design requirement

S′(S)＝a×S⁴+b×S3+c×S2+d×S+e

S′(H，S)＝a(H)×S⁴+b(H)×S³+c(H)×S²+d(H)×S+e(H)

In one embodiment, the conversion method further includes:

judging whether the gain value is in an interval [1,2 ];

when the gain value is smaller than 1, the gain value takes a value of 1; and

and when the gain value is larger than 2, the gain value takes 2.

In this embodiment, the normalized stimulus value signal W according to the white sub-pixel_YAnd calculating the gray-scale value W of the white sub-pixel, wherein the value range of W is 0-255. Then, calculating the stimulation value with large correlation between the white sub-pixel and the red stimulation value signal according to the gray level value W of the white sub-pixelSignal W_XAnd a stimulus value signal W having a large correlation with the blue stimulus value signal_Z。

Wherein the content of the first and second substances,

W＝W_Y ¹/γW_Y×255

wherein, the

And said γ W_ZRespectively is the W_Y、W_XAnd W_ZThe corresponding power function.

It is understood that the color mixture color of the red, green, and blue subpixels in the RGB display mode is the same as or as close as possible to the color mixture color of the white, red, green, and blue subpixels in the WRGB display mode, i.e., R'_X＝R″_X+W_X，G′_Y＝G″_Y+W_Y，B′_Z＝B″_Z+W_ZThe effect of the tristimulus values of the white sub-pixel on the red, green and blue sub-pixels should be eliminated. In this embodiment, the first stimulus value signal R 'after the gain processing'_X＝Gain×R_XThe gain-processed second stimulus value signal G'_Y＝Gain×G_YThe gain-processed third stimulus value signal B'_Z＝Gain×B_ZNormalized stimulus value signal W of the white sub-pixel_Y＝Min(R′_X，G′_Y，B′_Z)。

In this embodiment, in the color gamut corresponding to the four-color data, the normalized stimulus value signal R ″ of the red sub-pixel_X＝R′_X-W_XWhat is, what isNormalized stimulus value signal G' of the green sub-pixel_Y＝G′_Y-W_YNormalized stimulus value signal B' of the blue sub-pixel_Z＝B′_Z-W_Z. Therefore, the overlapping part of the white sub-pixel is eliminated in the red, green and blue sub-pixels, so that the color mixture color of the red sub-pixel, the green sub-pixel and the blue sub-pixel in the RGB display mode is the same as or close to the color mixture color of the white sub-pixel, the red sub-pixel, the green sub-pixel and the blue sub-pixel in the WRGB display mode. It should be noted that, when the normalized stimulus value signal of the red/green/blue sub-pixel is greater than or equal to 1, the normalized stimulus value signal of the red/green/blue sub-pixel takes a value of 1.

In one embodiment, the conversion method further includes:

W_out＝W_Y ¹/γW_Y×255

R_out＝R″_X ¹/γR_x×255

G_out＝G″_Y ¹/γ_Y×255

B_out＝B″_Z ¹/γB_Z×255

calculating the overlapping of a stimulus function X, a stimulus function Y and a stimulus function Z with the penetration spectrum of the green sub-pixel respectively, wherein the overlapping part of the penetration spectrum of the green sub-pixel and the stimulus function Y is the largest, and determining a stimulus value signal G in the tri-stimulus value signal of the green sub-pixel according to the calculation result_YFor the green sub-pixel tri-stimulus value signal middle pairStimulus value signal with maximum color mixing, and applying the stimulus value signal G_YAs the second stimulus value signal; and

Based on the same inventive concept, the application also provides a device for converting three-color data into four-color data, which comprises a memory and at least one processor. The memory is for storing computer instructions. The at least one processor is communicatively coupled to the memory and configured to receive the computer instructions from the memory and execute, according to the computer instructions:

judging whether the maximum value is less than 2 times of the minimum value;

if yes, the gain value of the pixel point is 2;

S′(S)＝a×S⁴+b×S³+c×S²+d×S+e

S′(H,S)＝a(H)×S⁴+b(H)×S³+c(H)×S²+d(H)×S+e(H)

In one embodiment, the at least one processor configured to execute the computer instructions is further configured to:

judging whether the gain value is in an interval [1,2 ];

when the gain value is smaller than 1, the gain value takes a value of 1; and

and when the gain value is larger than 2, the gain value takes 2.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A method for converting three color data to four color data, comprising:

determining the maximum value and the minimum value in the first stimulation value signal, the second stimulation value signal and the third stimulation value signal corresponding to each pixel point, and judging whether the maximum value is less than 2 times of the minimum value; if yes, the gain value of the pixel point is 2; otherwise, calculating the color mixing saturation corresponding to the pixel point in the three primary color gamut according to the first stimulus value signal, the second stimulus value signal and the third stimulus value signal;

calculating the color mixing saturation corresponding to the pixel point in the four primary color gamut according to the color mixing saturation corresponding to the pixel point in the three primary color gamut and a preset mapping relation;

determining the gain value of each pixel point according to the color mixing saturation corresponding to the pixel point in the four primary color gamut;

calculating a difference value between the first stimulus value signal after the gain processing and an X stimulus value signal having a large relationship with a red stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the red sub-pixel, calculating a difference value between the second stimulus value signal after the gain processing and a Y stimulus value signal having a large relationship with a green stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the green sub-pixel, and calculating a difference value between the third stimulus value signal after the gain processing and a Z stimulus value signal having a large relationship with a blue stimulus value signal among the tristimulus values signals of the white sub-pixel to be used as a normalized stimulus value signal of the blue sub-pixel.

2. The conversion method according to claim 1, wherein the calculating the saturation of the mixed color corresponding to the pixel point in the four-primary-color gamut according to the saturation of the mixed color corresponding to the pixel point in the three-primary-color gamut and a preset mapping relationship comprises:

3. The conversion method according to claim 1, wherein the calculating of the saturation of the mixed color corresponding to the pixel point by the saturation of the mixed color in the three primary color gamut and the preset mapping relationship comprises:

S′(S)＝a×S⁴+b×S³+c×S²+d×S+e

4. The conversion method according to claim 1, wherein the calculating of the saturation of the mixed color corresponding to the pixel point by the saturation of the mixed color in the three primary color gamut and the preset mapping relationship comprises:

S′(H，S)＝a(H)×S⁴+b(H)×S³+c(H)×S²+d(H)×S+e(H)

5. The conversion method according to any one of claims 2 to 4, further comprising:

judging whether the gain value is in an interval [1,2 ];

when the gain value is smaller than 1, the gain value takes a value of 1; and

and when the gain value is larger than 2, the gain value takes 2.

6. The conversion method according to claim 1, wherein the determining the first stimulus value signal having the greatest influence on mixed color among the tristimulus value signals of the red sub-pixel, the second stimulus value signal having the greatest influence on mixed color among the tristimulus value signals of the green sub-pixel, and the third stimulus value signal having the greatest influence on mixed color among the tristimulus value signals of the blue sub-pixel comprises:

calculating penetration spectra of stimulus function X, stimulus function Y and stimulus function Z and the red sub-pixel respectivelyWherein the overlap of the penetration spectrum of the red sub-pixel with the stimulus function X is maximal, determining a stimulus value signal R of the red sub-pixel tristimulus value signals from the calculation result_XThe stimulus value signal with the maximum color mixing in the red sub-pixel tri-stimulus value signal R_XAs the first stimulus value signal;

7. The conversion method of claim 1, further comprising:

8. A method for converting three color data to four color data, comprising:

determining the maximum value and the minimum value in the first stimulus value signal, the second stimulus value signal and the third stimulus value signal corresponding to the nth pixel point, and judging whether the maximum value is less than 2 times of the minimum value; if yes, the gain value of the nth pixel point takes a value of 2; otherwise, calculating the color mixing saturation corresponding to the nth pixel point in the three primary color gamut according to the first stimulus value signal, the second stimulus value signal and the third stimulus value signal;

calculating the color mixing saturation corresponding to the nth pixel point in the four primary color gamut according to the color mixing saturation corresponding to the nth pixel point in the three primary color gamut and a preset mapping relation;

determining a gain value of the nth pixel point according to the color mixing saturation corresponding to the nth pixel point in the four primary color gamut;

9. A device for converting three-color data to four-color data, said device comprising:

a memory for storing computer instructions; and

at least one processor, communicatively coupled to the memory, for receiving the computer instructions in the memory and performing the method of converting three-color data into four-color data according to any one of claims 1 to 8.