TW201443866A - Color temperature adjusting method of display device - Google Patents

Abstract

A color temperature adjusting method of a display device includes follow steps: generating a color temperature curve according a color temperature range, the Planckian locus of CIE 1931 color space and CIE daylight locus; calculating a target color temperature on the color temperature curve corresponding to a target color coordinates; generating a new brightness ratio of red, green and blue respectively according to the target color coordinates and the tristimulus values of the brightness red, the brightness green and the brightness blue of the display device; generating a coefficient of red, green and blue respectively according to the new brightness ratios of red, green and blue and the tristimulus values of red, green and blue; and adjusting color temperature of the display device according to the coefficients of red, green and blue.

Description

Color temperature adjustment method of display device

The present invention relates to a color temperature adjustment method, and more particularly to a color temperature adjustment method applied to a display device.

In the design of display devices, color taste is an important design factor and can be specifically represented by chromaticity coordinates. Conventional Techniques For color temperature adjustment of display devices, the color gamut of the target color temperature is often calibrated on the Planckian locus or CIE daylight locus of the CIE 1931 color space. However, the color coordinates of the high color temperature defined by the two curves will make the display screen appear purple or pink visually; otherwise, the color coordinates of the low color temperature defined by the two curves will make the display screen It is visually reddish.

However, for the average viewer, the color displayed on the screen when the color temperature is used is relatively blue, and the color displayed on the screen when the temperature is low is more yellow. Therefore, the conventional technique defines the color coordinates of the target color temperature on the Planck trajectory or the CIE daylight trajectory of the CIE 1931 chromaticity space, which does not conform to the general viewer's visual experience, and may degrade the viewer's viewing quality.

The present invention provides a color temperature adjustment method for a display device, comprising the steps of: generating a color temperature curve based on a color temperature range, a Planck trajectory of a CIE 1931 chromaticity space, and a CIE daylight trajectory in a CIE 1931 chromaticity space; a target color coordinate corresponding to the color temperature on the color temperature curve; a new brightness ratio of red, green, and blue is generated according to the respective color stimuli of the target color coordinates and the most bright red, green, and blue colors of the display device; The new brightness ratios of red, green, and blue, and the tristimulus values of red, green, and blue respectively produce one of red, green, and blue coefficients; and those based on red, green, and blue The number adjusts the color temperature of the display device.

As described above, in the color temperature adjustment method of the display device of the present case, a new color temperature curve generated in the CIE 1931 chromaticity space is generated according to the color temperature range, the Planck trajectory of the CIE 1931 chromaticity space, and the CIE daylight trajectory, and The target color coordinates corresponding to the target color temperature on the color temperature curve are calculated, thereby generating new brightness ratios of red, green, and blue, and the coefficients of red, green, and blue, thereby adjusting the color temperature of the display device. Thereby, the color displayed by the display device can be made to conform to the visual perception of the general viewer.

A~E, S01~S05‧‧‧ steps

D‧‧‧second corresponding color coordinates

P‧‧‧first corresponding color coordinates

U1, X1‧‧‧ Planck track

U2, X2‧‧‧ daylight track

U3, X3‧‧‧ color temperature curve

FIG. 1 is a schematic flow chart of a method for adjusting a color temperature of a display device according to an embodiment of the present invention.

2 is an enlarged schematic view of a Planck trajectory, a daylight trajectory, and a color temperature curve defined by the present invention in a CIE 1960 chromaticity space.

Figure 3 is a flow chart showing the process of generating a new color temperature curve in the present case.

4 is a relative schematic diagram of a Planck trajectory, a daylight trajectory, and a color temperature curve defined by the present invention in a CIE 1960 chromaticity space.

Figure 5 is a relative schematic diagram of the Planck's trajectory, the daylight trajectory, and the color temperature curve defined by the present invention in the CIE 1931 chromaticity space.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method of adjusting a color temperature of a display device according to a preferred embodiment of the present invention will be described with reference to the accompanying drawings, wherein the same elements will be described with the same reference numerals.

Please refer to FIG. 1 and FIG. 2 , wherein FIG. 1 is a schematic flow chart of a color temperature adjustment method of a display device according to a preferred embodiment of the present invention, and FIG. 2 is a Planck trajectory in a CIE 1960 chromaticity space. An enlarged schematic view of the daylight trajectory and the color temperature curve defined by the present invention. The display device may be, for example, a liquid crystal display device or an organic light emitting diode display device. Here, a liquid crystal display device is taken as an example.

As shown in FIG. 1, the color temperature adjustment method includes steps S01 to S05.

First, step S01 is: a color temperature curve generated in the CIE 1931 chromaticity space according to a color temperature range, a Planck trajectory of the CIE 1931 chromaticity space, and a CIE daylight trajectory. In this embodiment, the color temperature range is, for example, between 4000K and 25000K (4000K ≦ color temperature) ≦ 25000K, the unit of color temperature is in absolute temperature (Kelvin). In other words, in order to meet the general viewer's visual experience, this case does not define the color coordinates of the target color temperature on the Planck trajectory or CIE daylight trajectory of the CIE 1931 chromaticity space, but redefine a new color temperature based on the two curves. Curve, this color temperature curve comparison can meet the visual perception of the average viewer.

Hereinafter, please refer to FIG. 2 to FIG. 5, first explaining how to generate a new color temperature curve. 3 is a flow chart of generating a new color temperature curve in the present invention, and FIG. 4 is a relative schematic diagram of a Planck trajectory, a daylight trajectory, and a color temperature curve defined by the present invention in a CIE 1960 chromaticity space, and FIG. 5 is a relative schematic diagram of the Planck trajectory, the daylight trajectory, and the color temperature curve defined by the present invention in the CIE 1931 chromaticity space. Wherein, the step of generating a new color temperature curve comprises steps A to E.

As shown in FIG. 2, first, step A is: calculating a first color coordinate (x _C , y _C ) of one of the color temperature ranges in the CIE 1931 chromaticity space on the Planck trajectory X1, and calculating the color temperature. One of the second color coordinates (x _D , y _D ) on the CIE daylight trajectory X2. Specifically, as shown in FIG. 5, in order to obtain a new color temperature curve X3 in the CIE 1931 chromaticity space, an initial sampling point may be sampled in the color temperature range (between 4000K and 25000K), for example, 4000K (also available) Different initial sampling points, such as 25000K or other values, and convert the 4000K color temperature T into the first color coordinate (x _C , y _C ) and CIE daylight trajectory X2 on the Planck trajectory X1 of the CIE 1931 chromaticity space. The second color coordinate (x _D , y _D ). Wherein, the formula (1) converted by the first color coordinate (x _C , y _C ) is: x _C = -3.0258469 (10 ⁹ /T ³ ) + 2.1070379 (10 ⁶ /T ² ) + 0.2226347 (10 ³ /T) +0.240390, y _C = 3.0817580x _C ³ -5.87338670x _C ² +3.75112997x _C -0.37001483, of which 4000K≦T≦25000K. In addition, the formula (2) for the conversion of the second color coordinate (x _D , y _D ) is:

After obtaining the first color coordinate (x _C , y _C ) and the second color coordinate (x _D , y _D ), then proceeding to step B: as shown in FIG. 4, the first color coordinate (x _C , y _C ) And converting the second color coordinate (x _D , y _D ) to the CIE 1960 chromaticity space to obtain a first corresponding color coordinate P(u _C , v _C ) and a second corresponding color coordinate D (u _D , v _D ). Its conversion formula (3) is: Next, step C is performed: generating a color temperature coordinate (u _New , v _New ) of the color temperature according to the first corresponding color coordinate P(u _C , v _C ) and the second corresponding color coordinate D (u _D , v _D ). In the present embodiment, referring to FIG. 2 and FIG. 4, step B, the color temperature T calculated Planckian locus on the CIE 1960 color space of the Ul of a first color corresponding to the coordinate P (u _C, v _C ) with a second corresponding color coordinate D(u _D , v _D ) on the CIE daylight trajectory U2, followed by step C from the second corresponding color coordinate D along the vector Extending out, you can get the new color temperature coordinates (u _New , v _New ) at this color temperature T in the CIE 1960 chromaticity space. Among them, the formula (4) for obtaining the color temperature coordinates (u _New , v _New ) is: Where P(u _C , v _C ) is the first corresponding color coordinate, D(u _D , v _D ) is the second corresponding color coordinate, (u _NEW , v _NEW ) is the new color temperature coordinate, and the α value can be Between 0.001 and 0.005. Preferably, the above alpha value is 0.003, however, in other embodiments, the designer may take different alpha values depending on different visual perception requirements.

Next, proceed to step D: convert the color temperature coordinates (u _New , v _New ) to the CIE 1931 chromaticity space to obtain a new color temperature coordinate (x _New , y _New ). Here, as shown in FIG. 5, the color temperature coordinate (u _New , v _New ) on the CIE 1960 chromaticity space is converted to the CIE 1931 chromaticity space by using the above formula (3) to obtain a new color temperature coordinate (x _New). , y _New ).

Finally, step E is performed: step A to step D are repeated to obtain the new color temperature coordinates (x _New , y _New ) of the complex color temperature in the color temperature range, thereby obtaining a color temperature curve X3. In this case, different color temperature values can be obtained according to an interval sampling value, and then corresponding new color temperature coordinates (x _New , y _New ) can be obtained respectively. In other words, in this embodiment, for example, the sample values can be sampled at intervals of 10K, and the color temperatures of 4010K, 4020K, 4030K, and 25000K are respectively repeated to perform steps A to D, and the corresponding complex color temperature coordinates corresponding to the CIE 1931 chromaticity space can be obtained. (x _New , y _New ), and all the new color temperature coordinates (x _New , y _New ) are connected into a curve to obtain the color temperature curve X3 of step S01. In particular, the above-mentioned 10K interval sampling value is only an example. In other embodiments, the interval sampling value may also take different values, and the smaller the value of the interval sampling value, the more accurate the color temperature curve X3.

Therefore, according to the Planck's trajectory X1 and the CIE daylight trajectory X2 of the CIE 1931 chromaticity space generated after the new color temperature curve X3 (Fig. 5) in the CIE 1931 chromaticity space, please refer to FIG. 1 again, and then proceed to step S02. : Calculate a target color coordinate (x _tw , y _tw ) corresponding to a target color temperature on the color temperature curve X3 (not shown). Here, the target color temperature is converted by the new color temperature curve X3 by the above steps A to D to obtain the target color coordinates (x _tw , y _tw ) corresponding to the target color temperature on the CIE 1931 chromaticity space. The target color temperature is the color temperature to be displayed in the image to be displayed by the display device, and the target color temperature range is still between 4000K and 25000K.

Next, proceeding to step S03: the respective color coordinates (x _tw , y _tw ) and the most bright red (R), green (G), and blue (B) of the display device are respectively in the CIE 1931 chromaticity space. The stimulus values produce a new brightness ratio of one of red, green, and blue, respectively. Here, the original three-stimulus values X, Y, and Z of the original brightest order of the display device to be adjusted in color temperature are respectively converted into CIE by the following formula (5) in the CIE 1931 chromaticity space. After the color coordinates (x, y) on the 1931 chromaticity space, the target color coordinates (x _tw , y _tw ) of the target color temperature are used to calculate the new luminance ratios of red, green, and blue using the following formula (6). For example, the original red color of the display device refers to R=255, G=0, B=0, and the green of the brightest step refers to R=0, G=255, B=0, and the brightest The blue of the order refers to R=0, G=0, and B=255.

The tristimulus values of the red, green and blue of the brightest order of the display device are: (X _R , Y _R , Z _R ), (X _G , Y _G , Z _G ), (X _B , Y _B , Z _B ), and the formula (5) is: x=X/(X+Y+Z), y=Y/(X+Y+Z), and the formula (6) of the new brightness ratio of the target color temperature is (case) The R is red, the upper and lower case G is green, and the upper and lower case B is blue):

After obtaining the new brightness ratio, proceeding to step S04: generating the new brightness ratios of red, green, and blue, and the respective tristimulus values X, Y, and Z of the red, green, and blue colors in the CIE 1931 chromaticity space. One of the red, green and blue coefficients ( Coef _R , Coef _G , Coef _B ). Here, the coefficients ( Coef _R , Coef _G , Coef _B ) are obtained by the following equation, wherein Coef _R is a coefficient of red, Coef _G is a coefficient of green, Coef _B is a coefficient of blue, and m is Display screen characteristics of the device.

Finally, step S05 is performed to adjust the color temperature of the display device according to the coefficients of red, green and blue ( Coef _R , Coef _G , Coef _B ). In this case, an adjustment matrix is generated according to the coefficients of the red, green and blue ( Coef _R , Coef _G , Coef _B ), and then the color temperature of the display device is changed according to the adjustment matrix. Wherein, the adjustment matrix is a 3×3 matrix and is:

Alternatively, in different implementations, a red, green, and blue lookup table (Look-up Table) may be generated according to the coefficients of red, green, and blue ( Coef _R , Coef _G , Coef _B ), respectively. LUT), and change the color temperature of the display device according to the lookup tables. The generation of these lookup tables can be as follows: , wherein the coefficients ( Coef _R , Coef _G , Coef _B ) are used to generate three sets of red, green, and blue lookup tables, and are written into the gamma table in the display card of the display device (the lookup table needs to be adjusted again) Within the range of values of the gamma table defined in the display card of the display device). With the adjustment matrix or the red, green, and blue lookup tables, you can adjust the color temperature of the display device accordingly. Since the actual adjustment action is not the focus of the present invention, and those skilled in the art can adjust the color temperature of the display device accordingly, the present invention will not be further described.

In summary, the color temperature adjustment method of the display device according to the present invention is based on the color temperature range, the Planck trajectory of the CIE 1931 chromaticity space, and the CIE daylight trajectory generated in CIE 1931. A new color temperature curve in the chromaticity space, and calculate the target color coordinates corresponding to the target color temperature on the color temperature curve, thereby generating new brightness ratios of red, green, and blue, and red, green, and blue colors. The coefficient, which in turn adjusts the color temperature of the display device. Thereby, the color displayed by the display device can be made to conform to the visual perception of the general viewer.

The above is intended to be illustrative only and not limiting. Any equivalent modifications or alterations to the spirit and scope of the invention are intended to be included in the scope of the appended claims.

S01~S05‧‧‧Steps

Claims (10)

A color temperature adjustment method for a display device, comprising: generating a color temperature curve on a CIE 1931 chromaticity space according to a color temperature range, a Planck trajectory of a CIE 1931 chromaticity space, and a CIE daylight trajectory; and calculating a target color temperature at the color temperature a target color coordinate corresponding to the curve; according to the target color coordinate and the three-stimulus values of the red, green and blue of the brightest step of the display device respectively, a new brightness ratio of red, green and blue is generated; The new brightness ratios of red, green, and blue, and the respective three stimulus values of red, green, and blue respectively produce one of red, green, and blue coefficients; and adjust the coefficients according to the coefficients of red, green, and blue. The color temperature of the display device. The color temperature adjustment method according to claim 1, wherein the color temperature range or the target color temperature is between 4000K and 25000K. The color temperature adjustment method according to claim 2, wherein in the step of generating the color temperature curve, the method comprises: A: calculating one of the color temperatures in the color temperature range on one of the Planck trajectories of the CIE 1931 chromaticity space a first color coordinate, and calculating a second color coordinate of the color temperature on the CIE daylight track; B, converting the first color coordinate and the second color coordinate to a CIE 1960 chromaticity space to obtain a first correspondence a color coordinate and a second corresponding color coordinate; C, generating a color temperature coordinate of the color temperature according to the first corresponding color coordinate and the second corresponding color coordinate; and D, converting the color temperature coordinate to the CIE 1931 chromaticity space, To get a new color temperature coordinate. The color temperature adjustment method of claim 3, wherein in the step of generating the color temperature curve, the method further comprises: E, repeating steps A to D to obtain the plurality of color temperatures in the color temperature range. The color temperature coordinates are obtained to obtain the color temperature curve. The color temperature adjustment method according to claim 4, wherein in the step of obtaining the new color temperature coordinates of the plurality of color temperatures in the color temperature range, the values of the color temperatures are obtained according to an interval sample value. The color temperature adjustment method according to claim 3, wherein in step C, the color temperature coordinate satisfies the following equation: Where P(u _C , v _C ) is the first corresponding color coordinate, D(u _D , v _D ) is the second corresponding color coordinate, (u _NEW , v _NEW ) is the color temperature coordinate, and α is Between 0.001 and 0.005. The color temperature adjustment method according to claim 1, wherein the step of generating the new brightness ratios of red, green and blue respectively comprises: converting the stimulus values of red, green and blue into CIE respectively. Color coordinates on the 1931 chromaticity space. The color temperature adjustment method of claim 1, wherein the step of adjusting a color temperature of the display device comprises: generating an adjustment matrix according to the coefficients of red, green, and blue; and changing according to the adjustment matrix; The color temperature of the display device. The color temperature adjustment method of claim 8, wherein the adjustment matrix is: And Coef _R is a coefficient of red, Coef _G is a coefficient of green, and Coef _B is a coefficient of blue. The color temperature adjustment method of claim 1, wherein the step of adjusting a color temperature of the display device comprises: generating one of red, green, and blue according to the coefficients of red, green, and blue, respectively. And changing the color temperature of the display device according to the lookup tables.