A method for optimizing parameters of a multi-primary color system

Abstract

The application discloses a multi-primary color system primary color parameter optimization method, comprising the following steps: step one, determining the primary color number and white point color temperature of a display; step two, obtaining color coordinates according to the spectrum of a primary color light source; step three, in the CIEXYZ space, setting the white point of a display gamut to be consistent with the white point of a target gamut, calculating the solution space of the multi-primary color system, and then obtaining the brightness of each primary color, and calculating the three stimulus values of all primary colors according to the color coordinates of each primary color; step four, selecting a uniform color space for color gamut evaluation, calculating the primary color vector of the primary color system, transforming the parallel polyhedron formed in the CIEXYZ space into the selected uniform color space, and obtaining the boundary of the display gamut; step five, comparing the display gamut boundaries corresponding to different points in the solution space, that is, obtaining the optimal brightness combination of each group of primary colors; comparing the solution spaces of different primary colors, that is, obtaining the optimal primary color combination, and realizing the primary color design of the multi-primary color display.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of multi-primary display technology, and in particular to a multi-primary system primary color parameter optimization method. BACKGROUND

[0002] With the development of display technology, display can achieve larger and larger color gamut. The current general display color gamut standard is sRGB, however this standard only covers a very small part of the color chart. The NTSC color gamut, which is currently the target of display color gamut evaluation, can only cover less than half of the color chart area. The current display standard with the largest color gamut area is the Rec.2020 standard, but it can only cover 73.8% of the xy color chart area. Moreover, the vast majority of current displays cannot reach Rec.2020. The current large color gamut display scheme can be mainly divided into two categories. One is still using three primary colors, and the area of the primary color triangle in the color chart is expanded by increasing the color purity of each primary color, to achieve large color gamut. The other is using more primary colors, i.e. multi-primary display technology, so that the color gamut of the display changes from a triangle to a polygon in the color chart, thereby increasing the color gamut area and achieving large color gamut display.

[0003] At present, due to the rapid development of nanotechnology, semiconductor and laser technology, the technology of using narrow linewidth LCD backlight (such as quantum dot backlight), narrow spectrum LED or laser as display light source has gradually matured, which solves the problem of insufficient primary color purity of previous displays, so that the primary color triangle can be expanded to near the boundary of the color chart. If further multi-primary color scheme is used, the color gamut of the display can be greatly increased to achieve super large color gamut display far beyond the current display color gamut. The key step to achieve super large color gamut display is to select reasonable primary color light to achieve the largest display color gamut under the number of primary colors.

[0004] For a three-primary color display scheme, the brightness optimization (metamerism) problem of the primary colors is not involved after the white point of the display is determined. When the number of primary colors is greater than 3, due to the metamerism problem brought by multi-primary color display, the brightness of the primary colors cannot be uniquely determined by the white point coordinates, and the brightness needs to be optimized to determine the maximum color gamut in the uniform color space. SUMMARY

[0005] The purpose of the present application is to provide a multi-primary system primary color parameter optimization method, a color gamut evaluation method based on the size of the color gamut volume in the uniform color space as the optimization standard of the primary color color and brightness, and an optimization algorithm to convert the primary color optimization problem of the display into a constrained nonlinear programming problem, thereby realizing the primary color optimization design of the display.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] A multi-primary color system base color parameter optimization method, comprising the following steps:

[0008] Step one: determine the base color number and white point color temperature of the display;

[0009] Step two: obtain the color coordinates according to the spectrum of the base color light source;

[0010] Step three: in the CIEXYZ space, set the white point of the display gamut to be consistent with the white point of the target gamut, calculate the solution space of the multi-primary color system, and then obtain the brightness of each base color, and calculate the tristimulus value of all base colors according to the color coordinates of each base color;

[0011] Step four: select a uniform color space for color gamut evaluation, calculate the base color vector of the base color system, and transform the parallel polyhedron formed in the CIEXYZ space into the selected uniform color space, thereby obtaining the boundary of the display color gamut;

[0012] Step five: compare the display color gamut boundaries corresponding to different points in the solution space, and obtain the optimal brightness combination of each group of base colors;

[0013] Compare the solution spaces of different base colors to obtain the optimal base color combination.

[0014] As a further scheme of the present application: in step one, the base color number of the display is marked as N, and the white point color is represented by the white point color coordinates (x white ,y white ) and the white point brightness Y white .

[0015] As a further scheme of the present application: in step three, the tristimulus value of the base color is obtained as follows:

[0016] According to the spectrum of the base color light source, the color coordinates are marked as (x i ,y i );

[0017] Arbitrarily select three base colors to obtain the following boundary condition restrictions:

[0018]

[0019]

[0020]

[0021] and

[0022]

[0023]

[0024]

[0025] The calculation result is

[0026] The j+3th primary color is expressed by the first three primary colors, and has

[0027]

[0028]

[0029]

[0030] And

[0031]

[0032]

[0033]

[0034] Let the luminance ratio of the j+3th primary color be Yj+3, then the multi-primary color system satisfies

[0035]

[0036] That is

[0037]

[0038] For the multi-primary color display system, the luminance of each primary color should be greater than 0, so

[0039]

[0040] The inequality set is the solution space of the multi-primary color system, and the dimension is N-3;

[0041] The point (k1, k2, …, k j ,…) in the solution space corresponds to the primary color luminance solution of the multi-primary color system

[0042]

[0043] After obtaining the luminance Y of each primary color, the tristimulus values of all primary colors are calculated according to the color coordinates (x i , y i ) of each primary color.

[0044] As a further scheme of the present application: for a light source with a wide spectrum, the normalized tristimulus value of the ith primary color light source can be calculated using the CIE standard observer curve and the normalized spectral curve S(λ) when the primary color light source power is 1W:

[0045]

[0046]

[0047]

[0048] wherein X i , Y i , Z i are the tristimulus values of the CIE standard colorimetric observer.

[0049] As a further aspect of the present application: for a light source with very narrow spectrum such as a laser light source, the normalized tristimulus values of the primary light source with wavelength λ i can be calculated by the following formula:

[0050]

[0051]

[0052]

[0053] wherein X i , X i , Y i , Z i are the tristimulus values of the CIE standard colorimetric observer.

[0054] The beneficial effects of the present application are:

[0055] (1) Compared with the traditional optimization standard of maximizing the area of the color gamut, the present application uses the uniform color space (UCS) and considers the luminance component not represented in the color gamut, so that the color gamut evaluation is more accurate and reasonable;

[0056] (2) The present application is suitable for the design of display color gamut with multiple primaries, and can realize fast optimization under the condition of using optimization algorithm, and can realize the primary design of multiple primary display which cannot be realized by traditional method;

[0057] (3) The present application includes all possible primary combinations under given primary coordinate parameters and white parameters, that is, the solution space is complete, that is, under given primary coordinate parameters and white parameters, there is no luminance parameter setting of a group of multiple primary systems not in the solution space;

[0058] (4) The present application can realize the color gamut optimization of multiple primary systems with arbitrary primary coordinate parameters in combination with the calculation of color gamut volume;

[0059] (5) The present application can further constrain the solution space (for example, increase the brightness limit of a certain base color solution) to obtain the solution space under the constraint condition, which is also complete under the constraint condition. BRIEF DESCRIPTION OF DRAWINGS

[0060] The present application will be further described below in conjunction with the accompanying drawings.

[0061] Figure 1 is a schematic diagram of the volume of the four-primary color gamut of the present application changing with changes;

[0062] Figure 2 is a schematic diagram of the volume of the four-primary color gamut of the present application;

[0063] Figure 3 is a schematic diagram of the six-primary color solution space of the present application;

[0064] Figure 4 is a schematic diagram of the volume of the six-primary color gamut of the present application. DETAILED DESCRIPTION

[0065] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0066] The present application is a multi-primary color system base color parameter optimization method, comprising:

[0067] S1: determining the number N of base colors of the display, the white point color coordinates (x whit ,y white ), and the white point brightness (x white ,y white );

[0068] S2: selecting each base color light source, calculating its color coordinates (x i ,y i ) according to the spectrum of each base color light source;

[0069] S3: in the CIE XYZ space, setting the white point of the display color gamut to be consistent with the white point of the target color gamut, and then arbitrarily selecting three base colors to obtain the following boundary condition limit:

[0070]

[0071]

[0072]

[0073] and

[0074]

[0075]

[0076]

[0077] Calculate

[0078] S4: the j+3th base color is represented by the first three base colors, which is

[0079]

[0080]

[0081]

[0082] and

[0083]

[0084]

[0085]

[0086] S5: let the luminance ratio of the j+3th base color be Yj+3, then the multi-base color system satisfies

[0087]

[0088] That is

[0089]

[0090] For a multi-base color display system, the luminance of each base color should be greater than 0, so

[0091]

[0092] The inequality set is the solution space of the multi-base color system, and the dimension is N-3;

[0093] S6: the point (k1, k2, …, k j ,…) in the solution space corresponds to the base color luminance solution of the multi-base color system

[0094]

[0095] After obtaining the luminance Y of each base color, the color coordinates (xi ,y i ) are obtained;

[0096] S7: Select a uniform color space (UCS) to evaluate the color gamut, and calculate the base color vector (X i ,Y i ,Z i ) of the base color system in the CIEXYZ space to form a parallel polyhedron, and transform it into the selected uniform color space, that is, the boundary of the display color gamut is obtained;

[0097] S8: Compare the display color gamut boundaries corresponding to different points in the solution space, and the optimal brightness combination of a group of base colors can be obtained; and compare the solution space of different base colors, and the optimal base color combination can be obtained;

[0098] The working principle of the application: according to the additive color mixing principle, the tristimulus values X, Y and Z of two colors are linearly added with different weights, that is, a new color can be obtained, wherein the weights represent the brightness of each color;

[0099] The colors displayed by the N-base color display are mixed by adjusting the brightness of the N base colors, and the first step of optimizing the color gamut of the display is to determine the normalized tristimulus values of each base color;

[0100] For a light source with a wide spectrum, the normalized tristimulus values of the i-th base color light source can be calculated using the CIE standard observer curve and the normalized spectral curve S(λ) of the base color light source with a power of 1W:

[0101]

[0102]

[0103]

[0104] For a light source with a very narrow spectrum such as a laser light source, the normalized tristimulus values of the base color light source with a wavelength of λ i can be calculated as follows:

[0105]

[0106]

[0107]

[0108] Where X i , Y i , Z i are the CIE standard color observer tristimulus value curves;

[0109] For N-primary color displays, the display gamut is represented in the CIEXYZ space by a parallel polyhedron spanned by N vectors (X i ,Y i ,Z i ); where the direction of each vector represents the color (i.e. color coordinates) of this primary, and the normalized intensity proportion a of each primary can vary between 0 and 1 to display different colors;

[0110] The color represented when all the normalized intensity proportions of the primaries are 1 is the white point of the display.

[0111] In one embodiment: analog four-primary and six-primary display systems are demonstrated

[0112] Color coordinates (x, y) R1 R2 G1 G2 B1 B2 3 primary colors - (0.7080,0.2920) (0.1700,0.7970) - (0.1310,0.0460) - 4 primary colors - (0.7080,0.2920) (0.1700,0.7970) (0.0743,0.8336) (0.1310,0.0460) - 6 primary colors (0.7300,0.2700) (0.7080,0.2920) (0.1700,0.7970) (0.0743,0.8336) (0.1310,0.0460) (0.1611,0.0138)

[0113] For the four-primary system:

[0114] The selected four-primary color coordinates are Rl (0.708, 0.292), Gl (0.17, 0.797), G2 (0.0743, 0.8336), Bl (0.141, 0.046), and the selected white point coordinates are (0.3127, 0.3290);

[0115] The first three primaries are used to represent the fourth primary, G2 (0.0743, 0.8336) as the fourth primary,

[0116] and the other three primaries R2, Gl, Bl are used;

[0117] The other three primaries R2, Gl, Bl are mixed in proportion to produce white, assuming the intensity of white is 100, according to the color coordinate relationship of color mixing:

[0118] X mix = X red + X green + X blue (1)

[0119] Y mix = Y red + Y green + Y blue (2)

[0120] Z mix = Z red + Z green + Z blue (3)

[0121]

[0122]

[0123]

[0124] The result is

[0125]

[0126] The fourth primary color brightness Y G2 is set to 100, using the first three primary colors to express, there are:

[0127] Y G2 = Y' R2 + Y' G1 + Y' B1 = 100 (8)

[0128] The above formula is obtained by combining the results:

[0129]

[0130] Using k1 as a coefficient to adjust the proportion of the fourth primary color, then a four-primary color display system needs to meet the following conditions:

[0131]

[0132]

[0133] The physical meaning of the above two formulas is that in order to increase the brightness of the fourth primary color, the brightness of the first three primary colors is reduced in proportion; In order to realize the four-primary color system, the brightness of the four primary colors needs to be greater than 0, and there is: Substituting the numerical value, a one-dimensional solution space is obtained:

[0134] 0 < k1 < 0.6415 (12)

[0135] The brightness of the four primary colors is:

[0136]

[0137] Among them, any value of k1 corresponds to a set of four-primary color display, such as Figure 1 As shown in Figure 2 The color gamut volume changes with the change; as The color gamut volume diagram is shown.

[0138] For six primary colors, R1 and B2 are added, and it is assumed that the fifth and sixth primary color brightness Y R1 and Y B2 are both 100, and the first three primary colors R2, G1, and B1 are used to mix the two primary colors, resulting in:

[0139]

[0140] To the two primary colors, add two parameters k2 and k3, refer to the above process of four primary colors, have

[0141]

[0142] Let each item on the left side of the equation be greater than 0, that is, the brightness of each primary color of the six primary color system is greater than 0, to obtain a three-dimensional solution space:

[0143]

[0144] The brightness of each primary color is:

[0145]

[0146] As shown in Figure 3 the solution space, as shown in Figure 4 the color gamut volume diagram.

[0147] The above has carried out the detailed description to one embodiment of the application, but the content described is only the preferred embodiment of the application, cannot be considered for limiting the implementation scope of the application. Any equivalent changes and improvements made according to the application scope should still belong to the patent coverage scope of the application.

Claims

1. A method for optimizing primary color parameters in a multi-primary color system, characterized in that, Includes the following steps: Step 1: Determine the primary color number of the monitor as N, and the white point color coordinates (x, y, y). white ,y white ) and white point brightness Y white ; Step 2: Obtain the color coordinates based on the spectrum of the primary color light source; Step 3: In the CIEXYZ space, the white point of the display color gamut is set to be consistent with the white point of the target color gamut. The solution space of the multi-primary color system is obtained by calculation, and then the brightness of each primary color is obtained. The tristimulus values ​​of all primary colors are calculated based on the color coordinates of each primary color. Step 4: Select a uniform color space for color gamut evaluation. Transform the parallel polyhedron spanned by the primary color vectors of the primary color system in CIEXYZ space into the selected uniform color space to obtain the boundary of the display color gamut. Step 5: Compare the color gamut boundaries corresponding to different points in the solution space to obtain the optimal brightness combination for each primary color. By comparing the solution spaces of different primary colors, the optimal combination of primary colors can be obtained; In step three, the steps for obtaining the tristimulus values ​​of the primary colors are as follows: Based on the spectrum of the primary color light source, the color coordinates are marked as (x i ,y i ); Choosing any three primary colors yields the following boundary condition constraints: and Calculated Representing the (j+3)th primary color using the first three primary colors, we have: and Let the brightness ratio of the (j+3)th primary color be k. j Then the multi-primary color system satisfies Right now For a multi-primary-color display system, the brightness of each primary color should be greater than 0, therefore: The system of inequalities is the solution space of the multi-primary color system, with a dimension of N-3, and the value range of j is [1, N-3]. Points (k1, k2, ..., k in solution space) j The primary color luminance solution of the multi-primary color system corresponding to (,…) is: After obtaining the brightness Y of each primary color, based on the chromaticity coordinates (x, y) of each primary color... i ,y i Find the tristimulus values ​​for all primary colors.

2. The method for optimizing primary color parameters of a multi-primary color system according to claim 1, characterized in that, For light sources with a wide spectrum, the normalized tristimulus value of the i-th primary color light source can be calculated using the CIE standard observer curve and the normalized spectral curve S(λ) when the power of the primary color light source is 1W: Among them, X i Y i Z i This is the CIE standard colorimetric observer tristimulus value curve.

3. The method for optimizing primary color parameters in a multi-primary color system according to claim 1, characterized in that, For light sources with extremely narrow spectra, such as laser sources, the wavelength is λ. i The normalized tristimulus values ​​of the primary color light source can be calculated using the following formula: Where X i Y i Z i This is the CIE standard colorimetric observer tristimulus value curve.

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