TWI391908B - Method for displaying color by a four-color display device - Google Patents

Description

Method for displaying color of four-color display

The present invention provides a four-color (red, green, blue, white) display for displaying a mixed color. More specifically, the present invention provides a method for correcting the white to red, green, and blue colors displayed by the four-color display. The contribution is to eliminate the method of generating color shift when the four-color display displays the mixed color.

A general display (such as a liquid crystal display) usually includes a backlight module and a color panel, and when the color is displayed, the light generated by the backlight module is conveniently used to generate a desired color through the color panel. In general, the display is mixed with three primary colors of red, green and blue on its color panel to produce the desired color. That is to say, one pixel of a general color panel includes three sub-pixels: a red sub-pixel, a green sub-pixel, and a blue sub-pixel. The display utilizes the light generated by its backlight module to penetrate the red sub-pixels of the color panel to produce a red, penetrating green sub-pixel of the color panel to produce a green, penetrating blue sub-pixel of the color panel to produce a blue color; Adjust the different transmittances (grayscale values) of the primary color sub-pixels to mix the desired colors. However, in order to increase the transmittance of the color panel of the display, a new generation of display uses a color panel having four colors (red, green, blue, and white). In this way, the intensity of the illumination required by the backlight module can be reduced, thereby reducing the power consumption of the backlight module. One pixel of the four-color color panel includes four sub-pixels: a red sub-pixel, a green sub-pixel, a blue sub-pixel, and a white sub-pixel. Therefore, when displaying a mixed color, a four-color display must simultaneously consider the contribution of white produced by white sub-pixels to the displayed mixed color. degree.

However, the white sub-pixels of the prior art four-color display are not pure white, but white with a slight color shift (hereinafter referred to as panel white). As a result, the prior art four-color display produces a color shift when a mixed color is to be displayed.

The present invention provides a method of displaying a mixed color in a four color display. The four-color display comprises a white sub-pixel having a panel white primary color, a first color sub-pixel, a first primary color, a second color sub-pixel, a second primary color and a third color sub-pixel, A third primary color. When the four-color display displays the mixed color, the four-color display receives an input first color grayscale value, an input second color grayscale value, and an input third color grayscale value. The method includes calculating a ratio of the first primary color to the white primary color of the panel to generate a first primary color weight value; and, according to the first primary color weight value, the input first color grayscale value, the input second color The grayscale value and the input third color grayscale value produce an output first color grayscale value to drive the first color subpixel.

Please refer to Figure 1. Figure 1 is a schematic diagram of the relative coordinates of the colors displayed by the sub-pixels of a four-color display on the CIE 1931 XYZ color coordinate system. As shown in Figure 1, the red R _P of the red sub-pixel of a four-color display (hereinafter referred to as the red primary color), the coordinates (x, y) on the CIE1931XYZ color coordinate system are (0.5918, 0.3422); the green sub-pixel Green G _P (hereinafter referred to as green primary color), the coordinates (x, y) on the CIE1931XYZ color coordinate system are (0.3684, 0.558), the blue B _{P of the} blue sub-pixel (hereinafter referred to as the blue primary color), at the CIE1931XYZ color coordinates The coordinates (x, y) on the system are (0.152, 0.1387), the white sub-pixel panel white W _P (hereinafter referred to as the panel white primary color), and the coordinates (x, y) on the CIE1931XYZ color coordinate system are (0.3292, 0.3353). ). In fact, the coordinates (x, y) of the correct white W _CORRECT on the CIE1931XYZ color coordinate system should be (0.313, 0.329). Therefore, the spirit of the present invention decomposes the panel white primary color W _P displayed by the white sub-pixels of the four-color display into a combination of the other three primary colors R _P , G _P , and B _P . In this way, the degree of contribution to the other primary colors R _P , G _P , and B _P (first weight values r, g, and b) when the white sub-pixel of the four-color display is displayed on the panel white primary color W _P is reversed. Then correct the problem of color shift.

Please refer to Figure 2. The second figure is the tri-stimulus values of the panel white primary color W _P , the red primary color R _P , the green primary color G _{P ,} and the blue primary color B _P . According to the x value and y value of the coordinates (x, y) of a color in the CIE1931XYZ color coordinate system, the tristimulus value XYZ of the color can be derived by the following formula: x=X/(X+Y+Z)... (1); =Y/(X+Y+Z)... (2); and z=(1-x-y)=Z/(X+Y+Z) (3).

Therefore, according to the above formulas (1), (2), (3), refer to the coordinates of the panel white primary color W _P , the red primary color R _P , the green primary color G _P and the blue primary color B _P in the CIE1931XYZ color coordinate system (x, y The x value and the y value can be used to derive the tristimulus value XYZ of the panel white primary color W _P , the red primary color R _P , the green primary color G _{P ,} and the blue primary color B _P . For example, the tristimulus value X _WP of the panel white primary color W _P is 122.33, the Y _WP is 124.6 and the Z _WP is 124.67, the tristimulus value X _RP of the red primary color R _P is 54.85, the Y _RP is 31.72, and the Z _RP is 6.12. , green primary tristimulus values X _GP G _P is 61.99, Y _GP is 124.6 and Z _GP 12.38, and blue primary colors B _P tristimulus values X _BP to 23.89, Y _BP 21.8 to 111.48 and Z _BP.

Therefore, according to the tristimulus value XYZ of the panel white primary color W _P , the red primary color R _P , the green primary color G _P and the blue primary color B _P , it can be inferred that the white sub-pixels are in the other primary colors R _P , G when the display panel white primary color W _P The red primary color weight value r, the green primary color weight value g, and the blue primary color weight value b of _P and B _P are as shown in the following equations (4) and (5): ...(4); Substituting the three stimulus values revealed in Figure 2 into (4) leads to:

According to the formula (5), it can be known that the weight values r, g, and b of the panel white primary color W _P in the red primary color R _P , the green primary color G _{P ,} and the blue primary color B _P are 0.9069, 0.793, and 0.9805, respectively.

When displaying a color (such as yellow), the four-color display first receives the red input grayscale value GL _RI , the green input grayscale value GL _GI, and the basket color input grayscale value GL _BI , and then the correction provided by the present invention. after the mode switching, the output of the red output grayscale value GL _RO, green output grayscale value GL _GO, the output grayscale value GL _BO blue and white output grayscale value GL _WO. In this way, the four-color display of the present invention can display a mixed color with a small color shift. The calculation is as follows: Y _IMAX = MAX(GL _RI , GL _GI , GL _BI )... (6); Y _IMIN =MIN(GL _RI , GL _GI , GL _BI )... (7); GL _WO =Y _IMIN ... (8); GL _RO = [GL _RI × K] - r × GL _WO ... (9); GL _GO = [GL _GI × K] - g × GL _WO ... (10); GL _BO = [GL _BI × K] - b × GL _WO (11); and K = (Y _IMIN + Y _IMAX ) / Y _IMAX = (GL _WO + Y _IMAX ) / Y _IMAX (12).

Y _IMAX is the grayscale value with the largest value among the grayscale values GL _RI , GL _GI , and GL _BI .

Y _IMIN is the grayscale value with the smallest value among the grayscale values GL _RI , GL _GI , and GL _BI .

In this way, through the calculation method provided by the present invention, the mixed color displayed by the four-color display can reduce the problem of color shift.

Please refer to Figure 3. Figure 3 is a flow diagram of a method 300 of displaying color for a four color display provided by the present invention. The steps are as follows: Step 301: Measure the color coordinates of the red primary color R _P of the red sub-pixel of the four-color display on the CIE1931XYZ color coordinate system; Step 302: Measure the green primary color G of the green sub-pixel of the four-color display _P color coordinates on the CIE1931XYZ color coordinate system; step 303: measuring the color coordinates of the blue primary color B _P of the blue sub-pixel of the four-color display on the CIE1931XYZ color coordinate system; step 304: measuring the four-color display The color coordinates of the white sub-pixel panel white primary color W _P on the CIE1931XYZ color coordinate system; Step 305: the red primary color R _P , the green primary color G _P , the blue primary color B _P and the panel white primary color measured according to steps 301-304 The color coordinates of W _P respectively calculate the red primary color weight value r, the green primary color weight value g, and the blue primary color weight value b; step 306: according to the input red grayscale value GL _RI , the input green grayscale value GL _GI, and the input blue The grayscale value GL _BI calculates the gain value K; step 307: calculates the output white grayscale value GL _WO according to the input red grayscale value GL _RI , the input green grayscale value GL _GI, and the input blue grayscale value GL _BI ; step 308: According to the red primary weight r, the gain value K, the output grayscale value of white _WO GL GL calculating _{the RO} value output grayscale of red; Step 309: The green primary weighting value g, the gain value K, outputs the white grayscale value GL is calculated _WO green output grayscale value GL _GO : Step 310: Calculate the output blue grayscale value GL _BO according to the blue primary color weight value g, the gain value K, and the output white grayscale value GL _WO ; Step 311: The four color display according to the output red grayscale value GL _RO , The output green grayscale value GL _GO , the output blue grayscale value GL _BO, and the output white grayscale value GL _WO respectively drive the red subpixel, the green subpixel, the blue subpixel, and the white sub of the four color display Pixels to display the blend color.

If the color coordinates of the red primary color, the green primary color, the blue primary color, and the panel white primary color of the four-color display on the CIE1931XYZ color coordinate system are known, steps 301-304 may be omitted, and directly in step 305, According to the formula (4), the magnitudes of the weight values r, g, and b are calculated. Step 306 calculates the magnitude of the gain value K according to equations (6), (7), (8), and (12). Step 307 calculates the size of the output white grayscale value GL _WO according to formulas (7) and (8). Step 308 ~ 310 according to equation (9), (10), (11), respectively, the red output is calculated grayscale value GL _RO, the output grayscale value GL _GO green and blue grayscale value of the output magnitude of GL _BO. After the above steps, the four-color display can correctly display the mixed color of the smaller color shift.

In summary, the method for displaying color of the four-color display provided by the present invention can correctly correct the influence of the white color of the pixel generated by the white sub-pixel in the four-color display on the red, green and blue sub-pixels, so as to make use of The four-color display of the method for displaying color provided by the present invention can correctly display a color with a small color shift, and provides a user with higher picture quality.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

X, Y, Z‧‧‧ three stimulation values

R _P ‧‧‧Red primary color

G _P ‧‧‧Green primary colors

B _P ‧‧‧Blue primary color

W _P ‧‧‧ panel white primary color

W _CORRECT ‧‧‧correct white

301~311‧‧‧Steps

Figure 1 is a schematic diagram of the relative coordinates of the colors displayed by the sub-pixels of a four-color display on the CIE 1931 XYZ color coordinate system.

Figure 2 shows the tristimulus values of the panel white primary color, red primary color, green primary color and blue primary color.

Figure 3 is a flow chart of a method for displaying colors of a four-color display provided by the present invention.

301~311‧‧‧Steps

Claims (3)

A four-color display for displaying a mixed color, the four-color display comprising a white sub-pixel having a panel of white primary colors and a first color sub-pixel having a first primary color and a second color sub-pixel having a first The two primary colors and a third color sub-pixel have a third primary color. When the four-color display displays the mixed color, the four-color display receives an input first color grayscale value, an input second color grayscale value, and a Entering a third color grayscale value, the method comprising: calculating a ratio of the first primary color to the white primary color of the panel to generate a first primary color weight value; and inputting the first color according to the first primary color weight value a grayscale value, the input second color grayscale value, and the input third color grayscale value, generating an output first color grayscale value to drive the first color subpixel; wherein the first primary color is calculated in the panel The proportion of the white primary color to generate the first primary color weight value comprises: a third stimulus value according to the panel white primary color, a third stimulation value of the first primary color, a third stimulation value of the second primary color, and a third primary color Stimulus value and Column formula, generating the first weight values primary color _{weights: X W = X R × r} + X G × g + X B × b; Y W = Y R × r + Y G × g + Y B × b; Z W = Z _R ×r+Z _G ×g+Z _B ×b; wherein X _W , Y _W , Z _W represent the tristimulus values of the white primary color of the panel; X _R , Y _R , Z _R represent the three primary stimuli of the first primary color Values; X _G , Y _G , Z _G represent the three stimulus values of the second primary color; X _B , Y _B , Z _B represent the three stimulus values of the third primary color; r represents the first primary color weight value; g represents a first a primary color weight value; b represents a third primary color weight value; wherein, according to the first primary color weight value, the input first color grayscale value, the input second color grayscale value, and the input third color grayscale value, Generating the output first color grayscale value comprises: generating an output white grayscale value according to the input first color grayscale value, the input second color grayscale value, and the input third color grayscale value; The white grayscale value is multiplied by the first primary color weight value; according to the input first color grayscale value, the input second color grayscale value, the input third color grayscale value, and the following formula, a gain value is generated: K =(Y _IMIN +Y _IMAX )/Y _IMAX Where K represents the gain value, Y _IMIN represents the input first color gray scale value, the input second color gray scale value, the input third color gray scale value has the smallest value, and Y _IMAX represents the input first color The grayscale value, the input second color grayscale value, the largest value among the input third color grayscale values, the multiplied by the input first color grayscale value; and the input first color grayscale value The product of the gain value is subtracted from the product of the output white grayscale value and the first primary color weight value to produce the output first color grayscale value. The method of claim 1, wherein calculating a ratio of the first primary color to the white primary color of the panel to generate the first primary color weight value further comprises: measuring a tristimulus value of the panel white primary color, the first Three primary stimulus values, the first The three primary color stimulus values and the third primary color three stimulation values. The method of claim 1, wherein generating the output white grayscale value according to the input first color grayscale value, the input second color grayscale value, and the input third color grayscale value comprises: taking the input The first color grayscale value, the input second color grayscale value, and the smallest of the input third color grayscale values are used as the output white grayscale value.