WO2005076252A1

WO2005076252A1 - Multi-primary color display and color conversion method for multi-primary color display

Info

Publication number: WO2005076252A1
Application number: PCT/JP2005/001888
Authority: WO
Inventors: Yoshifumi Shimodaira; Masaki Takaya
Original assignee: National University Corporation Shizuoka University
Priority date: 2004-02-10
Filing date: 2005-02-09
Publication date: 2005-08-18

Abstract

A multi-primary color display using multi-color emitters emitting more than three primary colors as light-emitting cells and thereby having a high substantial energy efficiency and a wide color range. A display body is a display device which has a light-emitting cell array composed of a matrix structure where in addition to three-primary color light-emitting cells of the normal three primary colors R, G, B, light-emitting cells of one or more primary colors having emission colors out of the area surrounded by a triangle on the chromaticity diagram of the three primary colors R, G, B are arranged. By a signal processing section body, light-emitting cells of one or more primary colors out of the area surrounded by a triangle on the RGB chromaticity diagram emit light only when the input image signal is not included in the area of the triangle composed of RGB. For the multi-primary color display, a color conversion method for uniquely determining multi-primary color values by linear programming is provided.

Description

Specification

Multi-primary display and color conversion method for multi-primary display

Technical field

[0001] The present invention provides a multi-primary display having a wide color gamut with substantially high energy efficiency and a color reproduction in the multi-primary display by using a multi-color luminous body exceeding three primary colors as a light emitting cell. The present invention relates to a color conversion method using a linear programming for improvement. Background art

[0002] (Background technology of multi-primary color display)

The color reproduction method of displays using a combination of light emitters of more than three primary colors has been expected to be realized.It seems that there was little power to physically mention light emitters other than the three primary colors. . Instead, there has been known a method of realizing multi-primary color display as a projection type by combining a plurality of display devices by performing color conversion using a color reproduction matrix circuit.

[0003] A specific example of the color reproduction system is disclosed in Japanese Patent Application Laid-Open No. 2000-253263 (published on September 14, 2000) invented by Takeo Osawa. According to Japanese Patent Application Laid-Open No. 2000-253263, a color reproduction system is configured to include a color conversion device for displaying a color image on a multi-primary color display. This is an arithmetic system that uses the continuity of data and color signal values to maximize the color gamut.

[0004] The color conversion device includes a maximum luminance signal calculation device and a color image display signal calculation device. The maximum luminance signal calculation device calculates a gamut vertex signal representing a vertex of a surface of a polyhedron constituting a color gamut surface of the display surrounding the input tristimulus value vector, and the input tristimulus value into a color gamut vertex vector. Calculate the weighting factor when expressed as a weighted linear sum of the stimulus values. The color image display signal calculation device calculates a color image signal for displaying an input tristimulus value from the signal of the color reproduction area vertex and the weight coefficient.

[0005] In the arithmetic system for color reproduction, specifically, a linear matrix operation is performed from XYZ data. Calculation and gradation correction, four display input signals C

I want one C.

Four

The display input signals C-C are within reasonable wavelength ranges where color reproduction is possible.

14

These are four color signals having different center wavelengths and wavelength ranges divided into two. Color signal C,

One

C is input to one color projector, and the color signals C and C are input to another color projector.

2 3 4

To display a color image consisting of the four primary colors. According to Japanese Patent Application Laid-Open No. 2000-253263, reference is made to a configuration method of a force display device which discloses means for generating a display input signal.

[0006] On the other hand, conventional displays use three primary colors as stimulus values. (Refer to the well-known document “Digital Pictures”.) Therefore, conventionally, in order to expand the color gamut, in a display using three or more primary colors or more, a plurality of colors used for expanding the color gamut are used. The primary colors are displayed at the outermost color of the color gamut on the chromaticity diagram, that is, the color purity is high, and the colors are combined. However, a light-emitting element with high color purity has a low luminous efficiency, so that when a display is configured, the power consumption becomes very large, and thus heat generation of the display is a problem. If the heat generation is large, the temperature rise of the device and its surroundings will increase. This has a negative effect on the operation and reliability of the system, and it is necessary to improve this point.

(Background Art of First and Second Color Conversion Methods Used for Multi-Primary Color Display)

The present invention provides a first color conversion method and a second color conversion method based on the first color conversion method, as described in detail later. Since these background technologies are largely common, the common portions will be described first, and then the unique background technology of the second color conversion method will be referred to.

[0008] In recent years, there are several documents on high-fidelity color reproduction. In other words, Masahiro Yamaguchi, Hideaki Haneishi and Nagaaki Oyama, the second non-patent document entitled “High Color Reproduction Imaging System Based on Spectral: Natural Vision” (Technical Report of the Institute of Image Information and Television Engineers, Vol. 26, No. 58, No. 7) — 12 pages, 2002), and the third non-patent document entitled “Development of a High-Detailed Color Management System Based on Human Perception, Its Application to the Reproduction of Records in Museums and Museums” (Heisei 8, According to the FY2009 IPA Creative Information Technology Development Project Results Report), the importance of high fidelity color reproduction in fields such as e-commerce, digital archiving, and telemedicine has been pointed out. [0009] On the other hand, one of the causes of deteriorating the accuracy of color reproduction is a narrow color gamut of a display. FIG. 5 shows the color gamut of HDTV (indicated by region A) and the human visible region (indicated by region B) in the uniform chromaticity diagram (UCS). The inside of the triangle shown in FIG. 5 is the range of colors that can be displayed on the HDTV, and it is clear that the display area is not enough for the visible area. The chromaticity u 'v' of UCS is equal to the distance on the chromaticity diagram and the human sense than the xy chromaticity. The conversion to the CIEXYZ color system power UCS chromaticity (u ', ν') is expressed by the formula This can be done in (1).

u, = (4X) / (X + 15Y + 3Z)

v '= (9Y) / (Χ + 15Y + 3Ζ) (1)

[0010] At present, the color gamut is wider than HDTV! Research on displays has been conducted! Here, the wide color gamut display is a display that can reproduce colors in a wide color gamut without lowering the maximum luminance, which only has a wide reproduction range on a chromaticity diagram. In order to develop a wide color gamut display with three primary colors like the existing devices, high saturation and high luminance primary colors are required. Generally, the luminous efficiency of a light emitting device decreases as the saturation increases. This makes wide color gamut displays using the three primary colors inefficient. This can be solved by using primary colors that satisfy the following two conditions. That is, a primary color with high saturation but not very high luminance and a primary color with high luminance but not high saturation are required. However, in this case, four or more primary colors are needed.

The six-primary-color display shown in FIG. 5 is a color gamut of a six-primary-color rear-projection display manufactured by Olympus, which is one of wide color gamut displays using multiple primary colors. By using four or more primary colors, a more efficient wide color gamut display can be realized than in the case of three primary colors. However, new problems also arise as the number of primary colors increases. The degree of freedom of color conversion is one of them. In existing three-primary-color displays, the tristimulus values XYZ of the colors and the three-primary colors RGB have a three-to-three relationship, so there is no degree of freedom in conversion, and unique mutual conversion is possible. However, as the number of primary colors increases, the relationship between tristimulus values and primary colors becomes three to four or more.Thus, there is a degree of freedom in converting the signal values of each primary color into tristimulus values, making it impossible to perform unique conversion. . This indicates that there are a plurality of combinations of primary colors for displaying a certain XYZ. For this reason, there are combinations of primary colors having poor luminous efficiency. The multi-primary-color display according to the present invention includes one or more types of primary-color light-emitting cells having a light-emitting color outside a range surrounded by a triangle on a chromaticity diagram composed of ordinary RGB, and the light-emitting cells are arranged in a matrix. It is configured using a cell array configured in a tritas array. In this multi-primary color display, a cell array is formed integrally with a signal processing section, so that a color image signal in a wide color gamut can be displayed effectively with high energy efficiency.

[0013] As described above, the display performs color reproduction by additive color mixture. On the primary color display, the tristimulus values X, Y, and Z of the output colors and the tristimulus values of each primary color

{(X, Υ,, "Ζ ι), (X, T ₂ , Z" ₂ ),..., (X „, Υ„, Ζ "„)} There is a relationship to do. For example, reference can be made to Non-Patent Document 4.

Note on [0014]

Here, X, ,, and あり are tristimulus values of the primary color η when the maximum luminance is output, and S is an input signal value for the primary color η. Since S takes a value of 0≤S≤1, it can be considered as a value obtained by normalizing the maximum luminance of the primary color n by 1. Hereinafter, S is referred to as the relative luminance of the primary color n. When the expressions (2) and (3) are expressed using a summary matrix, the conversion of the tristimulus value XYZ from the relative luminance value of each primary color is given by the following expression (4).

[0016] Further, from equation (4), conversion of the XYZ forces into relative luminance of each primary color is represented by the following equation (5).

Here, in Equation (5), when the number of primary colors is 3, since the coefficient matrix is a square matrix, the inverse matrix is determined arbitrarily, and conversion can be performed without any problem. However, when the number of primary colors is exceeded, the coefficient becomes a matrix of 3 * n (n> 3), so it is not possible to find a unique inverse matrix! / ,.

[0018] Several studies have been conducted to address this problem, and have been published as fifth to seventh non-patent documents.

[0019] The fifth non-patent document is a paper entitled "Toshiji Terachi, Takeo Osawa, Masahiro Yamaguchi, and Nagaaki Oyama", "Color Matching Experiment Using Six Primary Color Displays" (Color Forum JAPAN 2001, pp. 97-100, 2001). This document describes a method of using color matching functions for each observer instead of using CIE-XYZ color matching functions for color reproduction, and a method of reproducing the shape of the spectral radiance estimated by a multi-spectral camera. I suggest. Color conversion can be performed uniquely by matching the number of dimensions of the color matching function to the number of dimensions of the display, or by reproducing spectral radiance with no degree of freedom. However, it is not practical to measure the color matching function for each individual or to use a multispectral camera.

[0020] The sixth non-patent document is "Ajito's Takeyuki, Osa ', Kenro, Obi's Takashi, Yamadachi' Masahiro, Ooyama's Nagaaki," Color Conversion Method of Multi-Primary Color Display Using Matrix Switch ", Optical Review Journal, Vol. 8, No. 3, 191-197 (2001) (Takeyuki AJITO, Kenro OHSAWA, Takashi OBI, Masahiro YAMAGUCHI and Nagaaki OH YAM A, "Color Conversion Method for Multiprimary Display Using Matrix Switching", Optical Review, Vol. .8, No. 3, pp. 191-197 (2001), which proposes a method for uniquely performing color conversion by dividing the color gamut created by primary colors into regions and assigning priorities. Although this method has the advantage of being able to perform high-speed conversion, it eliminates the degree of freedom only by priority for each area, and considers other effective uses of degrees of freedom. I can't.

[0021] The seventh non-patent document is written by Motomura Hideo, “A multi-source using linear interpolation method on isoluminance plane. Color Conversion of Color Displays ”, SID Journal, Vol. 11, No. 2, pp. 371--387 (2003) (Hideto MOTOMURA, color conversion for a multi-primary display using linear interpolation on equ luminance plane method (LIQUID) , Journal of the SID, 11/2, pp. 371-387 (2003) .In this document, it is possible to perform conversion with no degree of freedom by using linear interpolation with three points of equal luminance. Yes, but as with the fifth non-patent document, it cannot take into account other effective uses of degrees of freedom.

Patent Document 1: JP-A-2000-253263

Non-Patent Document 1: A. N. Netravali and B. G. Haskell, "Digital Pictures", Plenum Press, 1988, "Digital Images" by A.N.

Non-Patent Document 2: Masahiro Yamaguchi, Hideaki Haneishi, Nagaaki Oyama, "High Color Reproduction Imaging System Based on Spectrum-Natural Vision", Technical Report of the Institute of Image Information and Television Engineers, Vol. 26, No. 58, pp. 112, 2002

Non-Patent Document 3: “Development of a High-Detailed Color Management System Based on Human Perception, Its Application to the Reproduction of Records in Art Museums and Museums”, Report on the FY1996 / 9 IPA Creative Information Technology Fostering Project

Non-Patent Document 4: "International Color Consortium:" ICC Profile Specification Version 3.2 "", 1995 (International and European Consortium: .IC Profile Specification Version 6.2, 1995

Non-Patent Document 5: Takeshi Terachi, Takeo Osawa, Masahiro Yamaguchi, and Nagaaki Oyama, "Color Matching Experiment Using Six Primary Color Displays", Color Forum JAPAN 2001, 97-100, 2001

Non-Patent Document 6: Ajito's Takeyuki, Ossa 'Kenlow, Obi's Takashi, Yamadachi' Masahiro, Ooyama Nagaaki, "Color conversion method of multi-primary color display using matrix switch", Optical Review Magazine, Vol. 8, No. 3, No. 191-197 (2001) (Takeyuki AJITO, Kenro OHSAWA, Takashi OBI, Masahiro YAMAGUCHI and Nagaaki OHYAMA, "Color Conversion Method for Multiprimary Display Using Matrix Switching, Optical Review, Vol. 8, No. 3, pp. 191- 197 (2001))

Non-Patent Document 7: Motomura Hideo, "Multi-primary color discs using linear interpolation on equi-luminance surfaces." Color Conversion of Play ", SID Journal, Vol. 11, No. 2, pp. 371-387 (2003) (Hideto MOTOYAMA, olor conversion for a multi-primary display using linear

interpolation on equi—luminance plane method (LIQUID;, Journal of the SID, 丄丄 / 2, pp.371-387 (2003))

Non-Patent Document 8: Masatoshi Saka, "Optimization of Linear Systems: One Purpose Power, Multipurpose", Morikita Publishing, 1984

Non-Patent Document 9: GB Dantzig, Upper bounds, secondary, by BB Danzig, "Upper bounds, second bounds, and block triangles in linear programming", Econometric Force, 23, 174—183 (1955) constraints ana olock triangularity in linear programming, Econometrica, 23, pp.174-183 (1955))

Disclosure of the invention

Problems to be solved by the invention

(Problems to be solved by invention of multi-primary display)

The problem to be solved is that, within the wavelength range where each color can be reproduced, a color signal of multi-primary colors having rationally divided different center wavelengths and wavelength ranges is input, and good color reproducibility is obtained. An object of the present invention is to provide an energy-efficient, wide-gamut, multi-primary-color display system capable of reproducing a color image by using the above method.

(Problem to be Solved by the Invention of the First Color Conversion Method Used for Multi-Primary Display) The problem to be solved is to use four or more primary colors to improve color reproducibility in a multi-primary color display. In the conversion of multi-primary colors, the value of multi-primary colors is one-dimensionally determined by minimizing the power consumption of a light emitting cell using linear programming.

(Problem to be Solved by Invention of Second Color Conversion Method Used for Multi-Primary Color Display) In the above-described first color conversion method for such a multi-primary color display, color data further exists outside the color gamut. In that case, the display color is not decided! Therefore, there is a problem that natural color reproduction is impaired for an image, and the display color is determined by solving this as a linear programming problem.

Means for solving the problem

(Means for Solving the Problems of the Invention of Multi-Primary Color Display) The multi-primary-color display according to the present invention includes light-emitting cells of one or more types of primary colors having a light-emitting color outside a range surrounded by a triangle on a chromaticity diagram of RGB, in addition to light-emitting cells of three primary colors of normal RGB. A light-emitting cell array constituted by a cell matrix configuration arranged with a display, a display unit main body including a driving circuit thereof, and when an XYZ signal is input, the three primary colors and one or more other types are displayed on the display unit main body. And a signal processing unit for supplying multi-primary-color signals corresponding to light-emitting cells of different primary colors, so that color image signals having a wide color gamut can be effectively displayed with high energy efficiency. Configure

In the multi-primary-color display having the above-described configuration, the light-emitting cells of one or more types of primary colors having emission colors outside the range surrounded by the triangle on the chromaticity diagram of RGB include three primary colors whose input image signals are composed of RGB. By controlling the signal processing unit so as to emit light only when it is not within the range of the emission color defined by the emission cell, high efficiency and energy efficiency can be realized effectively.

(Means for Solving the Problems of the Invention of the First Color Conversion Method Used for Multi-Primary Display)

The invention of the first color conversion method used for a multi-primary color display applies a linear programming method for minimizing power consumption when determining a matrix value of the multi-primary colors in the multi-primary color conversion of the multi-primary display, A multi-primary color display that solves the degree of freedom in determining multi-primary color values in color conversion by replacing the objective function with a linear programming problem that uses power consumption, thereby simultaneously improving color reproducibility and minimizing power consumption. It provides a color conversion method.

(Means for Solving the Problems of the Invention of the Second Color Conversion Method Used for Multi-Primary Color Display)

The invention of the second color conversion method used for a multi-primary color display is a problem by performing mapping that lowers the chromaticity at a constant luminance along a straight line passing through the input tristimulus values and the chromaticity values of the white point in the image. To provide a color conversion method capable of natural color reproduction for an image containing much color data outside the color gamut.

The invention's effect (Effect of Invention of Multi-Primary Color Display)

An object that exceeds the color gamut of the normal display standard is displayed by reproducing colors with medium brightness and high saturation using newly added primary colors. In this case as well, the image is displayed in an appropriate combination of the ordinary three primary colors and the new primary colors. In this way, the saturation is large! / Is low in luminous efficiency! And the element is low in saturation! Is used in combination with the element with high luminous efficiency. Energy-efficient displays with a much wider color gamut. Therefore, since the problem of temperature rise due to heat generation can be solved, a display with high luminance in a wide color gamut can be realized relatively easily.

(Effect of Invention of First Color Conversion Method Used for Multi-Primary Color Display)

By using the linear programming, there is a degree of freedom in the color conversion of multi-primary colors in a multi-primary display with four or more primary colors. Therefore, by replacing the problem of the degree of freedom in color conversion with a linear programming problem with the power consumption of the objective function, we were able to find the combination with the lowest power consumption. This has the effect of improving color reproducibility in multi-primary color displays without increasing power consumption!

(Effect of Invention of Second Color Conversion Method Used for Multi-Primary Color Display)

By using the linear programming, there is a degree of freedom in the color conversion of multi-primary colors in a multi-primary display with four or more primary colors. Therefore, since color data outside the color gamut is converted into a color gamut by mapping based on linear programming, natural color reproduction can be realized for an image containing a large amount of color data outside the color gamut! / There is an effect.

Brief Description of Drawings

FIG. 1 is a diagram showing an example of display area division in a multi-primary-color display according to the present invention.

FIG. 2 is a diagram showing an example of a cell arrangement composed of five primary colors R, G, B, G, B.

b b

FIG. 3 is a diagram showing a connection between a signal processing unit main body and a display unit main body of a display according to the present invention.

FIG. 4 is a diagram showing a configuration of a color gamut determination processing means and an optimal combination processing means of five primary colors.

FIG. 5 is a diagram showing each color range region on a UCS chromaticity diagram.

FIG. 6 is an algorithm flow chart of the simplex method. FIG. 7 is a view showing a light emission color measuring device of an LED.

FIG. 8 is a diagram showing emission luminance characteristics of an LED.

FIG. 9 is a diagram showing chromaticity of LED emission colors on a UCS chromaticity diagram.

FIG. 10 is a diagram showing a frequency distribution of a ratio of a minimum power consumption to a maximum power consumption.

FIG. 11 is an 8-bit grayscale image representing input values of six primary colors.

FIG. 12 is a color chart.

FIG. 13 is an image reproduced on a six-primary-color display.

FIG. 14 is a diagram showing each color range area on a UCS chromaticity diagram.

FIG. 15 is an image showing an output result on a multi-primary-color display when no mapping is performed.

FIG. 16 is an image showing an output result on a multi-primary-color display when mapping is performed. Explanation of symbols

[0033] 1 Signal processing unit main body

2 Display unit

3 Judgment processing means

4 Combination optimization processing means

101 stabilized DC power supply

102 circuits

103 Luminance measuring instrument

104 LED

105 glass plate

106 Perfect reflection type light diffuser

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment of Multi-Primary Color Display)

The configuration scheme according to the present invention is significantly wider than the color gamut of a standard display color display standard (for example, HD TV standard)! Uses four or more types of light-emitting substances to display the image information that has high energy efficiency, but achieves the required brightness without effectively reducing the color gamut. This is a method for realizing a display with energy efficiency.

Hereinafter, the basic concept of the present invention will be described. When the color of an object in the natural world is represented as the vertical axis: lightness, radial direction: saturation, and circumferential direction: color in three-dimensional coordinates of a color, a color with a large lightness exists near the achromatic color axis. Many colors fall within the gamut of standard displays (eg, HDTV gamut). However, there are many colors whose object brightness is relatively small, exceeding the color gamut of a standard display. In addition, some artificial colors created by light-emitting elements such as paints, paints, dyes, and LEDs exceed the color gamut of standard displays. On the other hand, lighter colors are within the gamut of a standard display. Considering the color distribution of such an object, we propose a method that can simultaneously realize the following (1) and (2).

[0036] As (1), a color in which the brightness of the object is large and the saturation is relatively small is displayed using three primary colors developed according to the current display standard such as HDTV. Many of these primary color elements have been put to practical use, and have high luminance and a very good balance between saturation and efficiency. In most cases, even very light colors of objects can be displayed using these three primary colors.

[0037] Conversely, as (2), conversely, an object that exceeds the color gamut of the conventional display standard and has a medium brightness and a high saturation color is displayed using a newly added primary color. In this case as well, the display is made in an appropriate combination of these three primary colors and the new primary colors. In this way, an element with high saturation but low luminous efficiency and an element with low saturation but high luminous efficiency are used in combination, so that when viewed as a whole display device, the energy efficiency in a wide color gamut is increased. Good things can be realized.

FIG. 1 shows an embodiment of display area division in a multi-primary-color display constructed according to the present invention. In FIG. 1, RGB is the three primary colors in the color gamut of a standard for displaying colors on a standard display (for example, the HDTV standard). G and B are newly added primary colors

b b

And is outside the color gamut formed by RGB. X and Y are in the CIE standard, and are given by the following equation by a linear combination of the three primary colors R, G, and B. ("Digital image

0 0 0

See Pictures (Digital Pictures) J, p. )

X = 2.365R -0.55G + 0.005Β

0 0 0

Y = -0. 897R + 1.426G —0.014B Z = -0.468R + 0.089G + 1.09B

0 0 0

In FIG. 1, faithful color reproduction and optimization of energy efficiency are achieved by determining an appropriate color gamut when displaying image information in a wide color gamut. The number of primary colors used to obtain the required luminance is an optimal number of 3 or more, for example, 5 in this embodiment. Since the area surrounded by the three primary colors RGB is displayed using the light-emitting elements of a normal display, the brightness can be increased. As already explained, G and B are examples of newly added primary colors. Therefore b b

For example, among colors in a range surrounded by triangles R, G, and B, four colors b b b b surrounded by G, B, G, and B

The colors in the rectangle are displayed using the primary colors G, B, G, and B. But any three prima b b

The range of colors that can be displayed using colors is determined in consideration of the brightness and energy consumption that must be displayed.

[0040] FIG. 2 shows a panel-type display b b composed of five primary colors R, G, B, G, and B.

1 shows an example of the cell arrangement of the luminescent material in the above. In FIG. 2, the first line is composed of a repetition pattern of R, G, R, Bbb, and the second line is composed of a repetition pattern power of G, B, G, B. The third line is the same repetition as the first line, and is shifted one column to the right from the first line. Similarly, the fourth line is shifted one column to the right from the second line, which is the same repetition as the second line. Therefore, the repetition pattern of R, G, B, B is formed in the first row, and the second row b

In the eyes, a repeating pattern of G, B, R, and G is formed.

b

In driving the cell array composed of rows and columns, one or a plurality of intersections of a matrix composed of rows and columns can be simultaneously accessed. Therefore, in this cell array, the line of each row is always driven, and the line-at-a-time scanning of the formation, in which the line force of the first column is sequentially driven and the lines of the second and third columns are driven, is appropriate. This is one of the cell driving methods. However, as long as each cell has a storage function, the scanning method is not limited to this. Also, the arrangement method of the five primary colors is not limited to the method shown in FIG. 2, and any combination pattern may be repeated.

Next, the display method of the display according to the present invention will be described. In Fig. 3, after the image signal is input, the five primary colors R, G, B, G, and B are calculated and displayed on the display.

1 shows a connection between a signal processing unit main body 1 and a display main unit 2 including a multi-primary-color display driving circuit. FIG. 4 shows an example of a detailed configuration of the signal processing unit main body 1 shown in FIG. Figure 4 As shown, the signal processing unit main body 1 is composed of a color gamut discrimination processing means 3 and an optimum combination processing means 4 for executing an optimum combination of the five primary color signals obtained by this discrimination processing.

In FIG. 4, the operation of the discrimination processing means 3 is executed as follows. XYZZCIE—When an RGB signal is input to the signal processing unit main body 1, the determination processing means 3 determines whether or not the input signal is included in the range of the triangle formed by the color signal RGB. If it is within the range of the triangle composed of RGB, the vector RGB is input to the primary color division section of group 1 included in the combination optimization processing means 4 and divided into individual RGB components and output. If it is outside the range of the triangle consisting of RGB, it is included in the range of the quadrangle consisting of G, B, B, G or b b

Determine whether or not. G, B, B b b if contained in the range consisting of G, B, B, G

, G are input to the primary color division section of group 2 included in the combination optimization processing means 4, and b b

The output is divided into individual G, B, B, and G components.

b b

[0044] If it is out of the range of the quadrilateral consisting of G, B, B, and G, the range b b b of the triangle of G, G, and R

It is determined whether the force is contained within or within the range of the triangle of B, B, R b

It is. According to the discrimination result, the vector G, G, R or the vector B, B, R

Is input to the primary color division section of the group 3 included in the conversion processing means 4, and the individual G, G, R components or B, B, R components are divided and output.

b

[0045] Each RGB component, G, B, B, G component, G, G, R component or B, B, R component is

R, G, B, and G B signals are individually input to the input terminals of the display by being input to the primary color group switching unit and combined with each other.

b b

(Embodiment of First Color Conversion Method Used for Multi-Primary Color Display)

The linear programming problem is an optimization problem that maximizes or minimizes the objective function Z under the constraint condition, and the constraint condition and the objective function are represented as a linear form. References to this issue can be found in Kazumasa Saka, "Optimization of Linear Systems <From One Purpose to Multipurpose>", Morikita Publishing (1984). Since the problem can be treated algebraically under the condition of linearity, the optimal solution can be obtained simply compared to the nonlinear optimization problem. Equation (6) shows the standard form of the linear programming problem.

Zz Xd 匕 Z = C X + C X +

1 1 2 2 n n

Objective function a X + a X + + + X ± d = b ax + ax +

21 1 22 2 2n n 2 2 ax + ax + ^eee + ax ± d = b (6) ml 1 m2 2 mn nmm

0≤x, d (j = l, 2,

a, c: Constant

(j = l, 2, ..., n: i = l, 2, ..., m)

On the other hand, the following two basic theorems are given to the linear programming. In other words, the first is "if there is a feasible solution, there is always a feasible basis solution." There is also an optimal solution in ".

By using this theorem, an optimal solution can be obtained by a finite number of combination searches.

However, when the number of variables increases, the number of combinations increases, and the processing takes time. Therefore, the simplex method is used. The simplex method can use the basic theorem of linear programming efficiently to determine the optimality by using the relative cost coefficient to obtain the optimal solution. Figure 6 shows the basic algorithm of the simplex method.

Next, a linear programming method in color conversion will be described. In order to use the linear programming for color conversion, a conversion formula from the relative luminance value of each primary color to XYZ and a range in which the relative luminance value can be taken are set as constraints, and some objective function may be set. Equation (7) below shows the color conversion problem converted to the standard form of linear programming.

Minimized z = c S + c S H he S

1 1 2 2 n n

Objective function X S + X S H hX S = X

1 1 2 2 n n

Y S + Y S H hY S = Y (7)

1 1 2 2 n n

Z S + Z S H hZ S = Z

1 1 2 2 n n

0≤S ≤1 (j = l, 2,

[0050] Comparing equations (6) and (7), there are two differences compared to the normal linear programming problem. One is the range of variables. In the ordinary linear programming problem, the range of the variable is 0 ≤ x.In performing the color conversion, the range of the relative luminance is 0 ≤ S ≤ 1, and the simplex method can be applied as it is. Can not. This is the missing variable for S ≤1 And solve it by incorporating it into the constraints as S _n + α = 1, or by using the upper bound method. A reference book on this subject can be found in the eighth non-patent document, G. B. Danzig, "Upper Limits in Linear Programming, Second Restrictions, and Block Triangles ，, Econometic Force, Vol. 23, pp. 174—183. , 1955 (GB Dantzig, "Upper bounds, secondary constraints ana block triangularity in linear programming, conometrica, 23, pp.174-183 (1955).

[0051] Another problem is that there is no missing Z margin variable (dj) in the problem of color conversion. In ordinary linear programming, the initial feasible basis solution is obtained by setting the missing Z-margin variable to a non-basis variable (= 0), and the simplex method is advanced using that. In the linear programming method used in color conversion, there are no missing Z-margin variables and the variables have upper bounds, so various combinations of two kinds of non-basis variables, 0 and 1, must be searched for. Therefore, it is difficult to find an initial feasible basis solution. This requires the use of a two-step simplex method. The two-stage simplex method obtains information in the first stage that finds or does not exist an initial feasible basis solution. The second step is to find the optimal solution from the initial feasible basis solution, or to obtain information such that the solution is unbounded (there is a small solution everywhere).

Next, color conversion in consideration of power consumption will be described. Since the constraints are determined as described above, color conversion can be performed only by providing the objective function. Because there is a degree of freedom in color conversion of multi-primary colors, there are also combinations of primary colors that increase power consumption in self-luminous displays. In order to find the value of the primary color that minimizes power consumption using linear programming, the relative luminance S and power consumption P of the primary color n must be expressed in a linear form as shown in the following equation (8). Also, the power consumption of the multi-primary color display that satisfies Equation (8) is expressed by Equation (9).

P = c X S (8)

P + P H hP = c S + c S H he S (9)

1 2 n 1 1 2 2 n n

The above equation (9) matches the objective function z of equation (7). Time gray scale control is one method of gray scale control where the power consumption actually becomes a linear form as shown in equation (9). Other control methods are also nonlinear, but have the characteristic that the higher the power consumption, the higher the brightness. ing. In linear programming, the base solution that can be obtained even if the accuracy of the objective function is not so accurate satisfies the constraints. Therefore, even if the relationship between relative luminance and power consumption is

There is not much problem even if it is approximated as 8).

In order to confirm the above, an embodiment of a specific color conversion method was configured, and the accuracy of color conversion and the degree of improvement in power consumption were examined using LEDs. The LEDs used are of a total of six types: five primary colors and white, selected in consideration of brightness and chromaticity. First, the relationship between the LED current and the luminance was measured. Figure 7 shows an overview of the measurement device. In the figure, a circuit 102 connected to a power supply 101 drives an LED 104 supported on a substrate. The LED 104 illuminates the front fully-reflective light diffusion device 106 via a glass plate 105 made of polished glass. The diffuse scattered light is measured by a luminance measuring device 103 which is a spectral radiation luminance meter. The space between the LED 104 and the glass plate 105 is surrounded by a light shielding tube. Figure 8 shows the relationship between LED current and brightness. It turns out that there is not much problem even if the linear approximation is performed. In addition, the color difference between the theoretical value and the measured value was 0.86 when color mixing was performed by combining the values obtained from the measurements to check the reliability of the LED over time and additive color mixing. This is within the secondary color difference (color difference is observed when compared side by side), and it is of no problem if used in experiments.

Next, with reference to FIG. 8, the LED current and the tristimulus value for obtaining the highest luminance were determined. Table 1 shows the tristimulus values and currents of the LEDs used in the experiment. FIG. 9 shows the chromaticity at this time.

[table 1]

A simulation experiment was performed assuming time gray scale control with a linear luminance characteristic. Time Inter-grayscale control is a method of changing the luminance according to the ONZOFF time ratio (duty ratio) of the LED. Since the current flows only during the ON time, the relationship between duty ratio and luminance is almost linear. From Table 1, the value of the objective function z is given by the following equation (10).

z = 294. OS + 323. OS + 322.8S

one two Three

+ 331. OS + 304.5S (+ 302.4S) (10)

4 5 6

[0057] With this objective function z, a combination that minimizes power consumption can be obtained. We randomly selected 100 types of colors within the color reproduction range created by LEDs, and calculated the power consumption by simulation. For comparison, calculations were also performed for all negative coefficients of the objective function. Thus, a combination that maximizes power consumption can be obtained. The calculation was performed using two types, one using white (6 primary colors) and the other not using (5 primary colors). As a result of simulating 100 kinds of colors, the power consumption per unit time when the power consumption was solved as the maximum was 447.62 mW (5 primary colors) and 472.36 mW (6 primary colors) on average. When solved as the minimum, the average was 359.03mW (5 primary colors) and 309.91mW (6 primary colors). It was confirmed that the amount of power was reduced by adding white having good luminous efficiency.

The above results show that depending on the primary colors used, the total energy consumption can be reduced even if the primary colors are increased. Furthermore, to determine how much power consumption has been improved, the ratio of the amount of power of the combination with the maximum power to the amount of power with the combination of the minimum power was calculated for 100 results. The case was 0.802, the case of 6 primary colors was 0.656, and the standard deviation was 0.085 for the 5 primary colors and 0.151 for the 6 primary colors. Figure 10 shows the actual distribution. It was found that the linear programming method can provide an efficient combination of primary colors.

Next, the linear programming is confirmed using the image data. So far, we have performed theoretical and simulation experiments on color conversion methods for multi-primary color displays that take power consumption into consideration. However, when multi-primary color conversion is performed on image data, the following two problems can be considered. That is, the first problem is that "pseudo contours occur due to the change in the ratio of primary colors", and the second problem is that "unnatural color reproduction due to gradation reproduction errors" .

[0060] In order to confirm whether or not this problem occurs with the method of the present invention, a 6 primary color rear projection type XYZ image color conversion was performed on the display. Since the 6 primary color rear projection display uses a projector, the power consumption of the lamp is constant, and the tristimulus value of each primary color is determined by the brightness and the spectral transmittance of the filter. Therefore, although power consumption cannot be examined, it is possible to confirm color reproduction. The device used for imaging was Olympus' 16-band multispectral camera capable of outputting tristimulus values. The objective function 実際 actually used was set to 1 for all coefficients as in the following equation (11).

z = S + S + S + S + S + S (11)

1 2 3 4 5 6

FIG. 11 shows the relative luminance of each primary color represented as a black and white image from 0 to 255. From upper left to lower right, the primary color is shifted from the short wavelength primary color to the long wavelength primary color, and the chromaticity is as shown in Fig. 5. Each color chart in the image has a color scheme as shown in Fig. 12, and it can be seen that each primary color has a gradation corresponding to the color of the color chart.

[0062] In the linear programming, since the space created by the constraint conditions and the objective function are linear, the optimal solution at the end point has the following characteristics: black depending on the primary color, many parts, and an image. . Figure 13 shows the image that was mixed and displayed on the display. Since there was uneven brightness due to the way the light source hits, it was confirmed that conversion was possible without any problem even for background parts where false contours were likely to occur. In addition, when the effect of the theoretical quantization error was calculated for this image data, it was confirmed that the color difference was 0.26 on average. 0.26 is within the discrimination color difference (colorimetric reproduction accuracy of the same object), which is a level at which there is no problem in color reproduction.

(Embodiment of Second Color Conversion Method Used for Multi-Primary Color Display)

The second color conversion method is the same as the first color conversion method described above, and furthermore, when color data outside the color gamut is input, if the present invention is not applied, the control is that there is no solution. And the data in progress. This data has no colorimetric meaning and cannot be used for mapping. in this case,

"First perform color conversion. If it is within the color gamut, end."

"Second, mapping is performed outside the color gamut.",

It is assumed that the processing is performed in three steps, "Third, color conversion is performed again."

In the first and third procedures, since the initial solution is required, the simplet method is performed twice each time the conversion is performed. Therefore, this method requires a total of four simplex methods. Shi Figure 6 shows the algorithm of the simplex method. In addition, the amount of calculation further increases because mapping is performed. Therefore, a new method of solving mapping and color conversion as one linear programming problem is adopted. The constraint condition and the objective function at this time can be expressed as Expression (12). Minimize _z = I (X-X)

org I

Objective function X + --- + X S -X 0

1 s + X S

1 2 2 n n

Y S + Y S +

1 1 2 2 n n org

Z S + Z S + --- + Z = 0

1 1 2 2 n s -z

n

(X—x) / (x-x) = (z-z) Z (z—Z) (12)

org w org

X ≤X≤X if (X ≤X)

org w org

X ≤X≤X if (X> X)

org w w org

0≤S ≤1 (j = l, 2, ..., n)

j

In the above equation (12), X, Υ, and Ζ are input tristimulus values, and χ and y are org org org ww w w of the white point in the image.

The xy chromaticity value. X, Y, Ζ are on a straight line passing through two points, X, Υ, Ζ and X, Υ, Ζ org org org w org w

It is in. Along this straight line, mapping is performed to lower the chromaticity at a constant luminance. A display with a wide color gamut originally does not require much complicated mapping, so such a linear mapping is no problem. The objective function z is given as the absolute value of the difference between X and X.

By doing so, it is possible to perform optimal mapping. In the gamut, the value of z is 0.

By using this method, color gamut mapping and color conversion can be performed simultaneously. However, this method cannot consider the luminous efficiency. Therefore, color conversion is performed in the following procedure.

(1) Perform mapping and color conversion

(2) Perform color conversion in consideration of luminous efficiency using the result of (1)

[0067] In this method, mapping and color conversion are treated as one linear programming problem, which is more efficient than performing two calculations alone. Although the linear programming is performed twice, the initial calculation gives the initial feasible basis solution of step (2). It is not necessary to use the speed, and the speed can be improved.

[0068] In order to confirm the above, an embodiment of a specific color conversion method was configured, and the state of improvement by the above-described mapping was examined. That is, the color conversion of the XYZ image was performed for the rear projection display of the six primary colors using the method described above. The color gamut of this display is as shown in FIG. Since this device uses a projector and the power consumption of the lamp is constant, it is not possible to consider the actual power consumption. Therefore, assuming that the luminous efficiencies of all the primary colors are linear and equal, the effectiveness of the above method is simulated. In this case, the coefficients of the objective function in step (2) above are all 1. The equipment used for photography was a 16-band multispectral camera capable of outputting XYZ images, and the images used were photographs of highly saturated cloth.

FIG. 15 and FIG. 16 show images obtained by converting an XYZ image and outputting the converted image to a display, using a digital camera. However, FIG. 15 shows an image without mapping, and data outside the color gamut is white. On the other hand, FIG. 16 shows an image on which mapping has been performed. Comparing the two, it was confirmed that color conversion and mapping were performed without any problem. Industrial applicability

[0070] (Industrial applicability of multi-primary color display)

Due to the configuration of the multi-primary color display described above, the G and B cells emit light only when the color signal component exists outside the range defined by RGB.

The light time is short enough. For this reason, the energy efficiency of the entire display in actual use can be improved. Accordingly, a large-sized high-brightness, high-gamut display can be easily realized, and a temperature rise during actual use can be suppressed. By such an operation, a large clear image can be realized on the display. Therefore, the present invention has the potential of realizing an image display for expressing the relationship between color design such as dyeing, clothing, CG, and the freshness of fresh fish, vegetables, living things, and the like! / Puru.

[0071] (Industrial applicability of the first color conversion method used for multi-primary display)

In the first color conversion method described above, the actual LED characteristics were measured by time grayscale control in which the luminance characteristics became linear, and the combination with the minimum power consumption was obtained by the method according to the present invention. The results obtained are compared with the results that maximize the power consumption by changing the sign of the objective function. At this time, it was confirmed that the power consumption was improved by about 20% when the five primary colors were used, and by 35% when white with good luminous efficiency was added. The results show that multiprimary displays used in HDTVs and other high-definition displays are designed and built using linear programming-based design techniques to reduce display power consumption. ing. Therefore, the technique of the present invention can be used for a large-area, high-definition display.

(Industrial Applicability of Second Color Conversion Method Used for Multi-Primary Color Display) The above-mentioned second color conversion method according to the present invention is a method for optimizing the color reproduction of a multi-primary display and planning the efficiency of the device. Widely available to.

Claims

The scope of the claims

[1] In general, in addition to the three primary color light emitting cells composed of RGB, one or more primary colors that emit light outside the range surrounded by a triangle on the chromaticity diagram composed of RGB. A light emitting cell array comprising a cell matrix configuration arranged with light emitting cells and a display circuit body including a driving circuit thereof, and when an XYZ signal is input, the three primary colors and other A signal processing unit for supplying multi-primary-color signal components corresponding to one or more types of primary color light-emitting cells, and effectively displays color image signals in a wide color gamut with high energy efficiency. Multi-primary color display configured to be able to.

[2] One or more primary color light-emitting cells having a light emission color outside the range surrounded by the triangle on the chromaticity diagram composed of RGB are the light emission defined by the three primary color light-emitting cells whose input image signal is composed of RGB. Only when the signal is not included in the range of the color, the signal processing part booklet emits light with +++.

X T ζ

2. The multi-primary-color display according to claim 1, wherein the multi-primary-color display is configured to be controlled by a body so as to effectively realize high energy efficiency.

[3] Tristimulus values of color X, Υ, Z and tristimulus values of n primary colors (n = 1, 2,... Η)

(X.,, '--Χ η,, Υ ₂ , Ϋ Ϋ Ϋ, Υ,,, ■ ■.,,)

, For i = l, 2,

However, when the relation 0≤S ≤1 is assumed,

Objective function Z for linear programming

Z = C + C S +

1 1 2 2 n n

Is the power consumption P (i hand,

P = c S

C _{; a} first determining means for determining a value under a condition satisfying

Said first resultant c by _means, the power consumption under the value (i = l, 2, · '· η) matrix relationship of the color tristimulus values while satisfying a condition that minimizes the sum of the A second determining means for determining the formula;

A color conversion method for a multi-primary color display comprising:

Let X, Ζ, and 入力 be the input tristimulus values and X and y be the xy chromaticity values of the white point in the image.

If X, Y, and Z are on a straight line passing through X, Υ, Ζ and X, Υ, Ζ, org org org org w org w

An objective function generator that gives the objective function z as the absolute value of the difference between X and X, and minimizes it org

A color conversion method for a multi-primary-color display having an optimum mapping processing means for performing an optimum mapping according to the following display formula.

Record

X S + X S H hX S -X = 0

1 1 2 2 n n

Y S + Y S H hY S = Y

1 1 2 2 n n org

Z S + Z S H hZ S — Z = 0

1 1 2 2 n n

(X—X) / (X—X) = (z-z) / (z—z)

org w org org w org

X ≤X≤X if (X ≤X)

org w org

X ≤X≤X if (X> X)

org w w org

0≤S ≤1 (j = l, 2, ..., n)