CN100483483C - Method for building LCD colors characterizing segment and space division model - Google Patents

Abstract

The invention discloses a method for constructing a color characterization segmented space model of a liquid crystal display. The model divides the display drive value space into three types of subspaces according to the chromaticity characteristics and inter-channel interference characteristics of the display under different drive values. According to the different characteristics of these three types of subspaces, the color characteristics of the display are respectively carried out. Through the division of space, the influence of chromaticity inconsistency and channel independence on the accuracy of color characterization is effectively weakened. The present invention also designs corresponding training samples, and deliberately selects the value on the boundary point as the training sample of the segmented space model, and the training sample on the boundary point is used for two adjacent segmental functions or functions in the subspace. Coefficient fitting, which not only efficiently utilizes the training samples, but also increases the continuity of the tristimulus values at the cutoff point. The piecewise-spatial model achieves high color prediction accuracy with a small number of training samples.

Description

A Method for Constructing a Segmented and Segmented Space Model of Liquid Crystal Display Color Characterization

technical field

The invention relates to a display device in a modern digital image color management system, in particular to a method for constructing a liquid crystal display color characterization segmented and spaced model.

Background technique

With the development of computer and multimedia technology, digital image devices such as scanners, digital cameras, monitors and color printers have been widely used in industrial production and daily life, but people are also affected by the benefits of digital image devices. It solves the problem of distortion when color transmission between different devices. The traditional color management system represented by CEPS (Color Electronic Prepress Systems) uses a closed-loop method to manage colors. With the openness and networking of color management, this color management system is increasingly unable to meet need. In order to solve the problem of inconsistent color transmission of different digital image devices, the International Color Consortium (ICC, International Color Consortium) was initiated and established in 1993 by companies such as Adobe, Agfa, Apple, Kodak, FOGRA, Microsoft, Silicon Graphics, Sun Microsystem and Taliget. , which defines an international standard for modern color management systems. The color transmission process of this standard is shown in Figure 1. First, the color characterization files of different digital image devices are generated, and then these color characterization files are called by the color management module (CMM, Color Management Module) to realize the color transmission between devices. The color characterization file of the device is essentially to establish the corresponding relationship between the device driver value and the device-independent color space, that is, the link space of the device feature description file (CIEXYZ or CIELAB).

Digital image devices are divided into input devices, display devices, and output devices. For example, scanners and digital cameras are input devices, monitors are display devices, and printers are output devices. Generally, the processing process of an image is as follows: firstly, the image is scanned by a scanner or taken by a digital camera and then transmitted to the computer, and the image is processed according to the needs, directly viewed or transmitted through the Internet or printed out by a printer. In the process, the display is in a transit hub position, so it is very important to characterize the color of the display device. Since liquid crystal displays are obviously superior to traditional cathode ray tube displays in terms of power consumption, brightness and volume, and are being used more and more widely, accurate color characterization of liquid crystal displays is even more important.

The color characterization model of the traditional cathode ray tube display is based on the assumption that the display satisfies chromaticity invariance and channel independence. Since the cathode ray tube display has a development history of several decades and the manufacturing process is relatively mature, most of the cathode Ray tube displays can meet these two assumptions, so simple models such as GOG (Gain Offset Gama) can be used to characterize the display well. However, the development history of liquid crystal displays is relatively short, and the technology is not very mature. , especially the luminous mechanism and characteristics are very different from cathode ray tube displays. Most liquid crystal displays cannot satisfy the two assumptions of channel independence and chromaticity constancy. Therefore, if you simply use GOG, etc. Models are used to characterize such displays by color, and the model prediction accuracy is relatively low.

At present, there are few simple and practical LCD color characterization models, and some even need to establish a three-dimensional lookup table of LCD device driving values RGB and CIE1931XYZ, which requires a large amount of measurement data, which is time-consuming and increases the storage of the color management system The space cannot meet the needs.

Contents of the invention

The invention provides a method for constructing a liquid crystal display color characteristic segmented segmental space model which is simple, requires few training samples to be measured and has high precision.

A method for constructing a liquid crystal display color characterization segmentation segmental space model, comprising the following steps:

(1) Set the display through the color temperature, brightness and contrast setting buttons of the liquid crystal display, so that the color temperature, brightness and contrast of the display can meet the use requirements, and at the same time ensure the CIE1931XYZ tristimulus value of the corresponding color when the drive value of the display is high (International Commission on Illumination 1931 standard Chromaticity observer tristimulus value) does not appear saturation phenomenon;

(2) Check the chromaticity characteristics of the monochromatic channel of the liquid crystal display, respectively measure the chromaticity coordinates x, y and z of the corresponding color when the monochromatic channel has different driving values, and if the measured value is CIE1931XYZ value, then remove the black point (R = G=B=0, R, G and B are respectively the driving values of red, green and blue channels) and then obtain its chromaticity coordinates x, y and z by the following formula:

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}}$

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Y</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}}$

z=1-x-y

If the measurement is Yxy (luminance is Y, chromaticity coordinates are x, y), then the chromaticity coordinate z is calculated by the following formula:

z=1-x-y

Respectively find the relationship between the red channel driving value and the corresponding x chromaticity coordinate, the relationship between the green channel driving value and the corresponding y chromaticity coordinate, and the relationship between the blue channel driving value and the corresponding z chromaticity coordinate;

(3) To check the interference characteristics between the channels of the liquid crystal display, measure the corresponding monochrome channel (the driving value of the other two channels is zero) and the mixed color channel (the driving value of the other two channels is the maximum value) corresponding to each channel. The CIE1931XYZ value of the corresponding color under different driving values of the channel. If the measured value is Yxy, the corresponding X, Y and Z values are calculated by the following formula:

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; Y</span>}$

Y=Y

$\mathrm{<span\; class="notranslate">\; Z</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}}{\mathrm{<span\; class="notranslate">\; the\; y</span>}}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; Y</span>}$

Draw the tone reproduction curve of the monochrome channel and mixed color channel corresponding to each channel. The specific red channel is the function curve of the normalized X and normalized red channel driving values, and the green channel is the normalized Y and normalized The normalized green channel is plotted as a function of drive values, and the blue channel is plotted as a function of normalized Z and normalized blue channel drive values. Find out how each channel is interfered by the other two channels;

(4) According to the chromaticity characteristics under different driving values of each channel and the interference characteristics between channels, the driving value of each channel is divided into three segments, and the two dividing points of the red channel are marked as (M _R , _NR ), and the green The channel is marked as (M _G , N _G ), and the blue channel is marked as (M _B , N _B );

(5) Use quadratic polynomials to express the relationship between the X, Y and Z tristimulus values in each subsection of the monochrome channel and the normalized drive value of the channel in this interval. For example, taking the red channel as an example, the tristimulus value It can be expressed as

$\left\{\begin{array}{cc}{T}_{\mathrm{Ri}}=a_{1i}+b_{1i}\&times;r+c_{1i}\&times;r^2& R<=m_R\\ T_{\mathrm{Ri}}=a_{2i}+b_{2i}\&times;r+c_{2i}\&times;r^2& m_R<R<=N_R\\ T_{\mathrm{Ri}}=a_{3i}+b_{3i}\&times;r+c_{3i}\&times;r^2& R>N_R\end{array}\right.$ (i is X, Y or Z)

In the formula, r is the normalized driving value of the red channel, T _Ri (i is X, Y or Z) is the tristimulus value of the corresponding color of the red channel, a _ji , b _ji and c _ji (j=1, 2, 3) is a constant, MR and _NR are respectively the low-middle cut-off point and the middle-high cut-off point of the red channel drive value, determined by the chromaticity _constant characteristic and channel independent characteristic of the display;

Do the same for the green and blue channels;

(6) Divide the entire driving value space into 27 subspaces through the 6 demarcation points of the three channels, and then divide the above 27 subspaces into three categories according to the interference characteristics between channels:

a. At most one of the driving values of the three channels is greater than the dividing point M of the corresponding channel, and there are 7 subspaces in total;

b. Two of the driving values of the three channels are greater than the driving value M of the corresponding channel, a total of 12 subspaces;

c. The driving values of the three channels are all greater than the driving value M of the corresponding channel, and there are 8 subspaces in total;

(7) Calculate the tristimulus value of the corresponding color when the driving value is located in the three types of spaces:

When the driving values of the three channels are in the type a space, regardless of the interference between the channels, the tri-stimulus values obtained by the segmental function of each driving value corresponding to the channels are directly added together, and then the tri-stimulus values corresponding to the black dots are added. Get the tristimulus value of the color corresponding to the mixed color channel, for example, when the driving values of the three channels of the mixed color are located in the R<=M _R , G<=M _G , B<= _MB subspaces in the 7 subspaces, the corresponding color The tristimulus value of can be expressed as

T _i =T _Black +T _Ri +T _Gi +T _Bi

Where T _Black is the tristimulus value of the black dot, T _Ri , T _Gi and T _Bi are the tristimulus values of the segmental function corresponding to the red, green and blue channel drive values, respectively. Do the same for other a-type subspaces;

When the driving values of the three channels are in the b-type space, in addition to the tristimulus values obtained in the a-type space, the interference between the two channels whose driving value is greater than the corresponding cut-off point M should also be considered, for example, when the three channels of the mixed color drive When the value is located in the M _R <R<=N _R , M _G <G<=N _G , B<=M _R subspaces in the 12 subspaces, the tristimulus value of the corresponding color can be expressed as

T _i ＝T _Black +T _Ri +T _Gi +T _Bi +d _i +e _i ×r×g

Among them, r and g are the normalized driving values of the red and green channels respectively, the latter two are interference items, and d _i and e _i are constants, which can be determined by fitting the training samples of this subspace. Do the same for other b-type subspaces;

When the driving values of the three channels are located in the c-type space, in addition to the tristimulus values obtained in the a-type space, the interference between the three channels needs to be considered, for example, when the driving values of the three channels of the mixed color are located in 8 subspaces M _R When <R<=N _R , M _G <G<= _NG , M _B <B<=N _B subspace, the tristimulus value of the corresponding color can be expressed as

T _i ＝T _Black +T _Ri +T _Gi +T _Bi +d _i +e _i ×r×g+f _i ×g×b+h _i ×r×b+k _i ×r×g×b

Where b is the normalized driving value of the blue channel, the last five items are interference items, d _i , e _i , fi _, h _i and _ki are constants, which can be determined by fitting training samples in this subspace. Do the same for other c-type subspaces;

(8) Set up the experimental device according to the IEC 61966-4 standard, and obtain training samples including the following three data sets:

The first data set is: (R, G, B) = (I _R , 0, 0), (R, G, B) = (0, I _G , 0), (R, G, B) = ( 0, 0, I _B ), where I _R of the red channel = M _R /3, 2×M _R /3, M _R , M _R +(N _R -M _R )/3, M _R +2×(N _R -M _R )/3, N _R , N _R +(R _max -N _R )/3, N _R +2×(R _max -N _R )/3 and R _max , where R _max is the maximum value of the red channel drive value. The blue and green channels I _G and I _B are taken in a similar way to the red channel, and the data set has a total of 27 training samples;

The second data set is: (R, G, B) = (J _R , J _G , M _B /2), (R, G, B) = (J _R , M _G /2, J _B ), ( R, G, B) = (M _R /2, J _G , J _B ), where J _R is M _R , _NR and R _max , J _G is M _G , N _G and G _max , and J _B is M _B , N _B and B _max , where G _max and B _max are the maximum driving values of the green and blue channels respectively, and the data set has a total of 27 sample combinations;

The third data set is: (R, G, B) = (L _R , I _G , L _B ), where L _R is M _R , _NR and R _max , and I _G is M _G , N _G and G _max , L _B is M _B , N _B and B _max , a total of 27 sample combinations;

If the calculated driving values in the above three data sets are decimals, they are rounded up to the nearest integer. All the above-mentioned measured data sets are subjected to black point removal as training samples for the segmented space model. The training samples obtained from the first data set are used to fit the piecewise function coefficients, the training samples obtained from the second data set are used to fit the coefficients of class b spatial interference items, and the training samples obtained from the third data set It is used for fitting the coefficient of the c-type spatial interference term;

The above three data sets can also select an appropriate number of training samples uniformly according to the inconstant chromaticity of the display in different segment intervals or spaces, channel interference characteristics, and the size of the interval or space, and the training samples at the demarcation point are used to compare with it. Two adjacent piecewise functions or coefficient fittings of equations in two spaces, so that the training samples can be efficiently used, and the tristimulus values near the cutoff point can be kept continuous;

(9) Using the least squares method, use each segment function obtained in step (8) and the training samples in the subspace to fit the corresponding segment function and subspace interference term coefficients respectively (wherein the training samples on the demarcation point It is used to fit the coefficients of two piecewise functions adjacent to it or equations in two spaces), to obtain the corresponding relationship between the display normalized drive values r, g, b and CIE1931XYZ tristimulus values in each subspace, and complete The color characterization of the display.

The present invention effectively weakens the influence of inconstant chromaticity and non-independent channels on the color characterization accuracy of the liquid crystal display through the division of the driving value space, and improves the prediction accuracy of the model. In addition, the present invention tries to select the demarcation point as the training sample, and the training sample on the demarcation point is used for the fitting of the function coefficients in the two adjacent segmental functions or subspaces, so that both the training sample and the subspace are efficiently utilized. Added model-predicted continuity of tristimulus values around cutoff points. The invention realizes the accurate color characterization of the liquid crystal display under the condition that the number of training samples is small.

Description of drawings

Figure 1 is a flow chart of color transmission in a modern color management system;

Fig. 2 is the change relationship diagram of the chromaticity coordinates of the three-color channel of the liquid crystal display with the driving value of the present invention;

Fig. 3 is the relation diagram of the influence of the green and blue channels of the present invention on the tone reproduction curve of the red channel;

Fig. 4 is an experimental device diagram of the segmented space model of the present invention.

Detailed ways

Taking a liquid crystal display with a digital drive value of 8 bits as an example, the segmented and spaced model of the color characterization of this display includes the following steps:

(1) Set the color temperature of the liquid crystal display through the color temperature setting button to make the color temperature meet the use requirements, and make the brightness and contrast of the liquid crystal display meet the requirements through the brightness and contrast setting buttons, and at the same time ensure the CIE1931XYZ tristimulus value of the corresponding color when the display driving value is high There is no saturation phenomenon;

(2) Check the chromaticity characteristics of the monochrome channel of the liquid crystal display, and use the PR-650 spectroradiometer to measure the driving values of the red, green and blue channels at 16, 32, 48, 64, 80, 96, 112, 128 respectively , 144, 160, 176, 192, 208, 224, 240 and 255 under the CIE1931XYZ value of the corresponding color, remove the black point (R=G=B=0, R, G and B are red, green and blue channels respectively driving value) and obtain its chromaticity coordinates x, y and z by the following formula:

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}}$

$\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; Y</span>}}{\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Y</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; Z</span>}}$

z=1-x-y

Find the relationship between the driving value of the red channel and the corresponding x chromaticity coordinate, the relationship between the driving value of the green channel and the corresponding y chromaticity coordinate, and the relationship between the driving value of the blue channel and the corresponding z chromaticity coordinate, as shown in Figure 2 Show;

(3) Check the interference characteristics between the channels of the liquid crystal display, and use the PR-650 spectroradiometer to measure the monochrome channel (the drive value of the other two channels is zero) and the mixed color channel (the other two channels The driving value of the maximum value) corresponds to the CIE1931XYZ value of the color under different driving values. The tristimulus values corresponding to the colors of the three monochrome channels have been obtained in step (2), and the driving values corresponding to the mixed color channels to be measured are ( _HR , 255,255), (255, H _G , 255) and (255,255, H _B ), wherein _HR , H _G and H _B are all 16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, 208, 224, 240 and 255.

Draw the tone reproduction curve corresponding to the monochrome channel and the mixed color channel corresponding to each channel. The specific red channel is the relationship between the normalized X and the normalized red channel driving value, and the green channel is the normalized Y and normalized The relationship between the normalized green channel drive value and the blue channel is the relationship between the normalized Z and the normalized blue channel drive value. Find out the interference of each channel by the other two channels. Figure 3 shows the interference of the red channel by the green and blue channels;

(4) According to the chromaticity characteristics under different driving values of each channel and the interference characteristics between channels, the driving value of each channel is divided into three segments, and the two dividing points of the red, green and blue channels are respectively taken as 64 and 128 .

(5) Use a quadratic polynomial to fit the relationship between the X, Y and Z tristimulus values in each subsection of the monochrome channel and the normalized driving value of the channel in this interval. For example, taking the red channel as an example, the tristimulus value can be expressed as

$\left\{\begin{array}{cc}{T}_{\mathrm{Ri}}=a_{1i}+b_{1i}\&times;r+c_{1i}\&times;r^2& R<=64\\ T_{\mathrm{Ri}}=a_{2i}+b_{2i}\&times;r+c_{2i}\&times;r^2& 64<R<=128\\ T_{\mathrm{Ri}}=a_{3i}+b_{3i}\&times;r+c_{3i}\&times;r^2& R>128\end{array}\right.$ (i is X, Y or Z)

In the formula, r is the normalized driving value of the red channel, T _Ri (i is X, Y or Z) is the tristimulus value, a _ji , b _ji and c _ji (j=1, 2, 3) are constants;

Do the same for the green and blue channels;

(6) Divide the entire driving value space into 27 subspaces through 6 demarcation points of the three channels, and divide these 27 subspaces into three categories according to the interference characteristics between channels:

a. Only one of the driving values of the three channels is greater than 64, and there are 7 subspaces in total;

b. Two of the driving values of the three channels are greater than 64, a total of 12 subspaces;

c. The driving values of the three channels are all greater than 64, with a total of 8 subspaces;

(7) Calculate the corresponding tristimulus values when the driving values are located in the three types of spaces:

When the driving values of the three channels are in the type a space, regardless of the interference between the channels, the tri-stimulus values obtained by the segmental function of each driving value corresponding to the channels are directly added together, and then the tri-stimulus values corresponding to the black dots are added. Get the tristimulus value of the mixed color channel, for example, when the three channel driving values of the mixed color are located in the R<=64, G<=64, B<=64 subspaces in the 7 subspaces, the tristimulus value of its corresponding color can be Expressed as

T _i =T _Black +T _Ri +T _Gi +T _Bi

Where T _Black is the tristimulus value of the black dot, T _Ri , T _Gi and T _Bi are the tristimulus values of the segmental function corresponding to the red, green and blue channel drive values, respectively. Do the same for other a-type subspaces;

When the driving values of the three channels are in the b-type space, in addition to the tristimulus values obtained in the a-type space, the interference between the two channels with a driving value greater than 64 should also be considered, for example, when the driving values of the three channels of the mixed color are in the When 64<R<=128, 64<G<=128, and B<=64 subspaces in the 12 subspaces, the tristimulus value of the corresponding color can be expressed as

T _i ＝T _Black +T _Ri +T _Gi +T _Bi +d _i +e _i ×r×g

Among them, r and g are the normalized driving values of the red and green channels respectively, the latter two are interference items, and d _i and e _i are constants, which can be determined by fitting the training samples of this subspace. Do the same for other b-type subspaces;

When the driving values of the three channels are in the c-type space, in addition to the tristimulus values obtained in the a-type space, the interference among the three channels needs to be considered, for example, when the driving values of the three channels of the mixed color are located in 64 of the 8 subspaces When <R<=128, 64<G<=128, 64<B<=128 subspace, the tristimulus value of its corresponding color can be expressed as

T _i ＝T _Black +T _Ri +T _Gi +T _Bi +d _i +e _i ×r×g+f _i ×g×b+h _i ×r×b+k _i ×r×g×b

Where b is the normalized driving value of the blue channel, the last five items are interference items, d _i , e _i , fi _, h _i and _ki are constants, which can be determined by fitting training samples in this subspace. Do the same for other c-type subspaces;

(8) Carry out the experiment, the experimental device is shown in Figure 4, the effective height of the screen is h, the distance between the screen and the measuring instrument is 4h, the size of the color block to be measured is h/5×h/5, and the color block to be measured is h/5×h/5. The block is displayed in the center of the screen, and the rest of the screen is set to black;

Use the PR-650 spectroradiometer to measure the training samples. The training samples include the following three data sets:

The first data set is: (R, G, B) = (I _R , 0, 0), (R, G, B) = (0, I _G , 0), (R, G, B) = ( 0, 0, _IB ). Take the red channel as an example, where I _R is 21, 43, 64, 85, 107, 128, 170, 213, and 255. where (21,0,0), (43,0,0) and (64,0,0) are used for the polynomial of T _Ri =a _li +b _li ×r+c _li ×r ² (R<=64) Fitting, (64,0,0), (85,0,0), (107,0,0) and (128,0,0) for T _Ri =a _2i +b _2i ×r+c _2i × Polynomial fitting of r ² (64<R<=128), (128,0,0), (170,0,0), (213,0,0) and (255,0,0) for T _Ri = polynomial fitting of a _3i +b _3i ×r+c _3i ×r ² (R>128). The blue and green channels I _G and I _B are taken and used similarly to the red channel. The data set has a total of 27 training samples;

The second data set is: (R, G, B) = (J _R , J _G , 32), (R, G, B) = (J _R , 32, J _B ), (R, G, B) =(32, J _G , J _B ), wherein J _R , J _G and J _B are all 64, 128 or 255, and there are 27 training samples in all of the three sets, which are used for data fitting of the b-type space interference item, so that Each subspace has 4 training samples. For example, the training samples of 64<R<=128, 64<G<=128 and B<=64 subspace are (64,64,32), (64,128,32), (128,64,32) and (128,128, 32), the training samples of the other 11 subspaces are similar to 64<R<=128, 64<G<=128, B<=64 subspaces;

The third data set is: (R, G, B)=(L _R , L _G , L _B ), where L _R , L _G and L _B are all 64, 128 or 255, and there are 27 sample combinations in total. The data fitting of the interference term in the c-type space makes each subspace have 8 training samples. For example 64<R<=128, 64<G<=128 and 64<B<=128 subspace, its training samples are (64,64,64), (64,64,128), (64,128,64), (64,128,128 ), (128, 64, 64), (128, 64, 128), (128, 128, 64) and (128, 128, 128). The method of taking other 7 subspaces is similar to 64<R<=128, 64<G<=128, 64<B<=128 subspaces;

The above data sets must be removed from the black spots before they can be used as training samples;

(9) Using the least squares method, use each segment function obtained in step (8) and the training samples in the subspace to fit the corresponding segment function and subspace interference term coefficients respectively (wherein the training samples on the demarcation point It is used to fit the coefficients of two piecewise functions adjacent to it or equations in two spaces), to obtain the corresponding relationship between the display normalized drive values r, g, b and CIE1931XYZ tristimulus values in each subspace, and complete The color characterization of the display.

Claims (1)

1. method that makes up LCD colors characterizing segment and space division model is characterized in that may further comprise the steps:

(1) colour temperature, the brightness and contrast by LCD is provided with button display is set, make display color temperature, brightness and contrast satisfy user demand, guarantee that simultaneously saturated phenomenon does not appear in display CIE1931XYZ tristimulus values of corresponding color when motivation value is very high;

(2) the chromaticity characteristic of test liquid crystal display redness, green, blue channel, chromaticity coordinates x, y and the z of corresponding color when measuring each passage different driving value respectively, find out the relation of the x chromaticity coordinates of red channel motivation value and correspondence, the relation of the y chromaticity coordinates of green channel motivation value and correspondence, the relation of the z chromaticity coordinates of blue channel motivation value and correspondence;

(3) the interchannel interference characteristic of test liquid crystal display, the CIE1931XYZ value of the color mixture passage corresponding color under this passage different driving value when the monochromatic passage the when motivation value of measuring other two passages of each passage correspondence respectively is zero and other two channels drive values are maximal value, the monochromatic passage of each passage correspondence of drawing and the tone reproduction curve of color mixture passage are found out the disturbed condition that each passage is subjected to two other passage;

(4) according to chromaticity characteristic and interchannel interference characteristic under each passage different driving value, the motivation value of each passage is divided into three sections, two separations of red channel are designated as M _R, N _R, two separations of green channel are designated as M _G, N _G, two separations of blue channel are designated as M _B, N _B, M wherein _RAnd N _RBe respectively in red channel motivation value low separation and in high separation, M _GAnd N _GBe respectively in green channel motivation value low separation and in high separation, M _BAnd N _BBe respectively in blue channel motivation value low separation and in high separation;

(5) represent that with quadratic polynomial X, Y and Z tristimulus values are with the relation of this passage normalization motivation value r, g, b in this interval in each piecewise interval of monochromatic passage respectively;

(6) by 6 separations of described three passages of step (4), be 27 sub spaces,, more above-mentioned 27 sub spaces be divided three classes according to interchannel interference characteristic with whole motivation value spatial division:

A. has only a separation M in the motivation value of three passages at most, totally 7 sub spaces greater than respective channel;

B., two separation M greater than respective channel are arranged, totally 12 sub spaces in the motivation value of three passages;

C. the motivation value of three passages is all greater than the separation M of respective channel, totally 8 sub spaces;

Described separation M is the low middle separation of each passage;

The tristimulus values of corresponding color when (7) calculating motivation value respectively and be positioned at three space-likes, when the motivation value of three passages is positioned at a space-like, need not to consider interchannel interference, after the tristimulus values addition that each motivation value respective channel piecewise function is tried to achieve, the tristimulus values of adding the stain correspondence promptly gets the tristimulus values of color mixture passage corresponding color; When the motivation value of three passages is positioned at the b space-like, except that the tristimulus values that a space-like obtains, also need consider two the interchannel interference of motivation value greater than corresponding separation M; When three channels drive values are positioned at the c space-like, except that the tristimulus values that a space-like obtains, also need consider three interchannel interference;

(8) according to IEC 61966-4 standard experimental provision is set, choosing the color of the motivation value correspondence in separation and even division piecewise interval or space measures, and the tristimulus values that measures is carried out stain remove, divide the training sample of spatial model as segmentation;

(9) utilize least square method, with each piecewise function that obtains in the step (8) and the training sample in the subspace respectively to its corresponding segments function and subspace distracter coefficient match, obtain the corresponding relation of display normalization motivation value r, g, b and CIE1931XYZ tristimulus values in each sub spaces, finish the colorimetric characterization of display.

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