Patent Publication Number: US-10789909-B2

Title: Picture adjusting method and display system

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a picture adjusting method and a display system and, more particularly, to a picture adjusting method and a display system capable of reducing brightness difference between two pictures. 
     2. Description of the Prior Art 
     At present, some display devices are capable of displaying a plurality of pictures in a picture by picture (PBP) manner, a picture in picture (PIP) manner, etc., for a user. When displaying a picture, the display device usually performs a gamma correction for the picture to adjust the brightness of the picture. However, if the brightness of two pictures is adjusted by an identical gamma curve, the brightness of the two pictures after adjustment may be different, such that the user may feel difference in vision as watching the two pictures. 
     SUMMARY OF THE INVENTION 
     An objective of the invention is to provide an image processing method and a display device capable of reducing brightness difference between two pictures, so as to solve the aforesaid problems. 
     According to an embodiment of the invention, a picture adjusting method comprises steps of displaying a first picture and a second picture; measuring a plurality of first original parameters in the first picture and measuring a plurality of second original parameters in the second picture for each of a plurality of color patterns, wherein the color patterns comprise a black pattern; calculating a first gain factor according to the first original parameters and the second original parameters of at least one of the color patterns except the black pattern; subtracting a product of the first original parameters of the black pattern and the first gain factor from the second original parameters of the black pattern to obtain a plurality of first offset values; adding the first offset values to the first original parameters of each color pattern to obtain a plurality of first updated parameters of each color pattern in the first picture; and multiplying the first updated parameters of each color pattern by a second gain factor to obtain a plurality of first adjusted parameters of each color pattern in the first picture. 
     According to another embodiment of the invention, a display system comprises a display module, a measuring unit and a processing unit. The display module displays a first picture and a second picture. The measuring unit measures a plurality of first original parameters in the first picture and measures a plurality of second original parameters in the second picture for each of a plurality of color patterns, wherein the color patterns comprise a black pattern. The processing unit calculates a first gain factor according to the first original parameters and the second original parameters of at least one of the color patterns except the black pattern. The processing unit subtracts a product of the first original parameters of the black pattern and the first gain factor from the second original parameters of the black pattern to obtain a plurality of first offset values. The processing unit adds the first offset values to the first original parameters of each color pattern to obtain a plurality of first updated parameters of each color pattern in the first picture. The processing unit multiplies the first updated parameters of each color pattern by a second gain factor to obtain a plurality of first adjusted parameters of each color pattern in the first picture. 
     As mentioned in the above, when displaying two pictures, the invention calculates the gain factors and the offset values according to the color patterns (e.g. black pattern, white pattern, red pattern, green pattern, blue pattern, etc.) in the two pictures and then adjusts the original parameters of each color pattern by the gain factors and the offset values. Accordingly, the invention can reduce brightness difference between the two pictures, such that the user will not feel obvious difference in vision as watching the two pictures. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a functional block diagram illustrating a display system according to an embodiment of the invention. 
         FIG. 2  is a flowchart illustrating a picture adjusting method according to an embodiment of the invention. 
         FIG. 3  is a flowchart illustrating a picture adjusting method according to another embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 ,  FIG. 1  is a functional block diagram illustrating a display system  1  according to an embodiment of the invention and  FIG. 2  is a flowchart illustrating a picture adjusting method according to an embodiment of the invention. The picture adjusting method shown in  FIG. 2  is adapted to the display system  1  shown in  FIG. 1 . 
     As shown in  FIG. 1 , the display system  1  comprises a display module  10 , a measuring unit  12  and a processing unit  14 . The display module  10  is configured to display a first picture P1 and a second picture P2 (step S 10  in  FIG. 2 ). In this embodiment, the display module  10  may be a display panel, wherein the first picture P1 and the second picture P2 may be displayed on the display panel in a picture by picture (PBP) manner, a picture in picture (PIP) manner, or other manners. At this time, the processing unit  14  may be disposed in the display panel or connected to the display panel externally. In another embodiment, the display module  10  may comprise two display devices, wherein the first picture P1 is displayed by one of the two display devices and the second picture P2 is displayed by another one of the two display devices. At this time, the processing unit  14  may be disposed in one of the two display devices or connected to the two display devices externally. Furthermore, the measuring unit  12  may be a color measuring instrument. 
     After displaying the first picture P1 and the second picture P2, the invention uses the measuring unit  12  to measure a plurality of first original parameters in the first picture P1 and measures a plurality of second original parameters in the second picture P2 for each of a plurality of color patterns (step S 12  in  FIG. 2 ). In this embodiment, the color patterns may comprise a black pattern W0, a white pattern W255, a red pattern R255, a green pattern G255 and a blue pattern B255. In an embodiment, the first original parameters of each color pattern in the first picture P1 may be represented by Table 1 below and the second original parameters of each color pattern in the second picture P2 may be represented by Table 2 below, wherein X, Y and Z are stimulus values of red, green and blue in CIE 1931 color space. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 First picture P1 
               
            
           
           
               
               
            
               
                   
                 First original parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Color pattern 
                 X1 
                 Y1 
                 Z1 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Black pattern 
                 0.261795 
                 0.25557 
                 0.516547 
               
               
                   
                 W0 
                   
                   
                   
               
               
                   
                 White pattern 
                 237.8584 
                 248.5469 
                 299.2774 
               
               
                   
                 W255 
                   
                   
                   
               
               
                   
                 Red pattern 
                 104.1663 
                 52.79401 
                 2.770775 
               
               
                   
                 R255 
                   
                   
                   
               
               
                   
                 Green pattern 
                 85.05317 
                 177.6342 
                 28.58803 
               
               
                   
                 G255 
                   
                   
                   
               
               
                   
                 Blue pattern 
                 48.44732 
                 17.95661 
                 267.6385 
               
               
                   
                 B255 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Second picture P2 
               
            
           
           
               
               
            
               
                   
                 Second original parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Color pattern 
                 X2 
                 Y2 
                 Z2 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Black pattern 
                 0.246363 
                 0.238195 
                 0.486357 
               
               
                   
                 W0 
                   
                   
                   
               
               
                   
                 White pattern 
                 226.7696 
                 236.7351 
                 287.4714 
               
               
                   
                 W255 
                   
                   
                   
               
               
                   
                 Red pattern 
                 98.24092 
                 49.76382 
                 2.656363 
               
               
                   
                 R255 
                   
                   
                   
               
               
                   
                 Green pattern 
                 81.77143 
                 169.6433 
                 27.21642 
               
               
                   
                 G255 
                   
                   
                   
               
               
                   
                 Blue pattern 
                 46.6137 
                 17.20572 
                 257.3841 
               
               
                   
                 B255 
               
               
                   
               
            
           
         
       
     
     Then, the processing unit  14  calculates a first gain factor according to the first original parameters and the second original parameters of at least one of the color patterns except the black pattern W0 (step S 14  in  FIG. 2 ). In this embodiment, the processing unit  14  may calculate a ratio of each second original parameter to each first original parameter of at least one of the white pattern W255, the red pattern R255, the green pattern G255 and the blue pattern B255 to obtain a plurality of ratios. Then, the processing unit  14  may take a specific value from the ratios to be the first gain factor, wherein the specific value may be a minimum value, a maximum value, an average value, a median value or other values. As shown in Table 3 below, the processing unit  14  may calculate a ratio of each second original parameter to each first original parameter of the white pattern W255, the red pattern R255, the green pattern G255 and the blue pattern B255 to obtain a plurality of ratios. At this time, the specific value served as the first gain factor may be a minimum value 0.942604, a maximum value 0.962152, an average value 0.955109, a median value 0.956599 or other values in Table 3. 
     
       
         
           
               
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                   
                 Ratio of second original parameter to first 
               
               
                   
                 original parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Color pattern 
                 X2/X1 
                 Y2/Y1 
                 Z2/Z1 
               
               
                   
               
               
                   
                 White pattern 
                 0.953381 
                 0.952477 
                 0.960552 
               
               
                   
                 W255 
                   
                   
                   
               
               
                   
                 Red pattern 
                 0.943116 
                 0.942604 
                 0.958708 
               
               
                   
                 R255 
                   
                   
                   
               
               
                   
                 Green pattern 
                 0.961409 
                 0.955014 
                 0.952022 
               
               
                   
                 G255 
                   
                   
                   
               
               
                   
                 Blue pattern 
                 0.962152 
                 0.958183 
                 0.961685 
               
               
                   
                 B255 
               
               
                   
               
            
           
         
       
     
     In another embodiment, the processing unit  14  may calculate a ratio of each second original parameter to each first original parameter of the white pattern W255 to obtain a plurality of ratios. Then, the processing unit  14  may take a matrix consisting of the ratios to be the first gain factor. As shown in Table 4 below, the matrix served as the first gain factor is [0.953381 0.952477 0.960552]. Needless to say, the processing unit  14  may also take a minimum value, a maximum value, an average value, a median value or other values in Table 4 to be the first gain factor. 
     
       
         
           
               
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                   
                 Ratio of second original parameter to first 
               
               
                   
                 original parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Color pattern 
                 X2/X1 
                 Y2/Y1 
                 Z2/Z1 
               
               
                   
               
               
                   
                 White pattern 
                 0.953381 
                 0.952477 
                 0.960552 
               
               
                   
                 W255 
               
               
                   
               
            
           
         
       
     
     In another embodiment, a first matrix 
                   [         104.1663         5   ⁢     2   .   7     ⁢   9401             2   .   7     ⁢   7   ⁢   0   ⁢   7   ⁢   7   ⁢   5             85.05371         17   ⁢     7   .   6     ⁢   3   ⁢   4   ⁢   2           2   ⁢     8   .   5     ⁢   8   ⁢   8   ⁢   0   ⁢   3             48.44732         17.9   ⁢   5661           2   ⁢   6   ⁢     7   .   6     ⁢   3   ⁢   8   ⁢   5           ]           
may consist of the first original parameters of the red pattern R255, the green pattern G255 and the blue pattern B255, and a second matrix
 
                   [         98.24092         4   ⁢     9   .   7     ⁢   6   ⁢   3   ⁢   8   ⁢   2             2   .   6     ⁢   5   ⁢   6   ⁢   3   ⁢   6   ⁢   3             81.77143         169.   ⁢   6   ⁢   4   ⁢   3   ⁢   3         27.21642           46.6137       17.20572         2   ⁢   5   ⁢   7   ⁢   .3841           ]           
may consist of the second original parameters of the red pattern R255, the green pattern G255 and the blue pattern B255. Then, the processing unit  14  may multiply the second matrix by an inverse matrix of the first matrix and sets negative value(s) to be zero, so as to obtain a third matrix
 
                     [           0   ⁢   .943189         0       0.000181               0   .   0     ⁢   0   ⁢   6   ⁢   9   ⁢   8   ⁢   2             0   .   9     ⁢   5   ⁢   2   ⁢   9   ⁢   5   ⁢   7         0               0   .   0     ⁢   0   ⁢   0   ⁢   6   ⁢   4   ⁢   2         0         0   ⁢   .961738           ]     .           
Then, the processing unit may take the third matrix to be the first gain factor.
 
     In the following, the maximum value 0.962152 in Table 3 is taken to be the first gain factor to illustrate the steps after the step S 14 . After obtaining the first gain factor, the processing unit  14  subtracts a product of the first original parameters of the black pattern W0 and the first gain factor from the second original parameters of the black pattern W0 to obtain a plurality of first offset values (step S 16  in  FIG. 2 ). It is assumed that the first gain factor is represented by G1, so the calculation and result of the first offset values are shown in Table 5 below. 
     
       
         
           
               
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                   
                 Subtract product of first original parameter and 
               
               
                 Black pattern 
                 first gain factor from second original parameter 
               
            
           
           
               
               
               
               
            
               
                 W0 
                 X2 − X1 * G1 
                 Y2 − Y1 * G1 
                 Z2 − Z1 * G1 
               
               
                   
               
               
                 First offset 
                 −0.00552 
                 −0.0077 
                 −0.01064 
               
               
                 value 
               
               
                   
               
            
           
         
       
     
     Then, the processing unit  14  adds the first offset values to the first original parameters of each color pattern to obtain a plurality of first updated parameters of each color pattern in the first picture P1 (step S 18  in  FIG. 2 ), as shown in Table 6 below. 
     
       
         
           
               
             
               
                 TABLE 6 
               
             
            
               
                   
               
               
                 First picture P1 
               
            
           
           
               
               
            
               
                   
                 First updated parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 X1′ = X1 − 
                 Y1′ = Y1 − 
                 Z1′ = Z1 − 
               
               
                   
                 Color pattern 
                 0.0052 
                 0.0077 
                 0.01064 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Black pattern 
                 0.256272 
                 0.247868 
                 0.505907 
               
               
                   
                 W0 
                   
                   
                   
               
               
                   
                 White pattern 
                 237.8529 
                 248.5392 
                 299.2667 
               
               
                   
                 W255 
                   
                   
                   
               
               
                   
                 Red pattern 
                 104.1608 
                 52.7863 
                 2.760134 
               
               
                   
                 R255 
                   
                   
                   
               
               
                   
                 Green pattern 
                 85.04818 
                 177.6265 
                 28.57739 
               
               
                   
                 G255 
                   
                   
                   
               
               
                   
                 Blue pattern 
                 48.4418 
                 17.9489 
                 267.6279 
               
               
                   
                 B255 
               
               
                   
               
            
           
         
       
     
     Then, the processing unit  14  multiplies the first updated parameters of each color pattern by a second gain factor to obtain a plurality of first adjusted parameters of each color pattern in the first picture P1 (step S 20  in  FIG. 2 ). In this embodiment, the processing unit  14  may take the aforesaid first gain factor to be the second gain factor. 
     In another embodiment, the processing unit  14  may calculate a ratio of each second original parameter to each first updated parameter of at least one of the white pattern W255, the red pattern R255, the green pattern G255 and the blue pattern B255 to obtain a plurality of ratios. Then, the processing unit  14  may take a specific value from the ratios to be the second gain factor, wherein the specific value may be a minimum value, a maximum value, an average value, a median value or other values. As shown in Table 7 below, the processing unit  14  may calculate a ratio of each second original parameter to each first updated parameter of the white pattern W255, the red pattern R255, the green pattern G255 and the blue pattern B255 to obtain a plurality of ratios. At this time, the specific value served as the second gain factor may be a minimum value 0.942741, a maximum value 0.962404, an average value 0.955524, a median value 0.956825 or other values in Table 7. 
     
       
         
           
               
               
             
               
                 TABLE 7 
               
             
            
               
                   
               
               
                   
                 Ratio of second original parameter to first 
               
               
                   
                 updated parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Color pattern 
                 X2/X1′ 
                 Y2/Y1′ 
                 Z2/Z1′ 
               
               
                   
               
               
                   
                 White pattern 
                 0.953403 
                 0.952506 
                 0.960586 
               
               
                   
                 W255 
                   
                   
                   
               
               
                   
                 Red pattern 
                 0.943166 
                 0.942741 
                 0.962404 
               
               
                   
                 R255 
                   
                   
                   
               
               
                   
                 Green pattern 
                 0.961472 
                 0.955056 
                 0.952376 
               
               
                   
                 G255 
                   
                   
                   
               
               
                   
                 Blue pattern 
                 0.962262 
                 0.958594 
                 0.961724 
               
               
                   
                 B255 
               
               
                   
               
            
           
         
       
     
     In another embodiment, the processing unit  14  may calculate a ratio of each second original parameter to each first updated parameter of the white pattern W255 to obtain a plurality of ratios. Then, the processing unit  14  may take a matrix consisting of the ratios to be the second gain factor. As shown in Table 8 below, the matrix served as the second gain factor is [0.953403 0.952506 0.960586]. 
     
       
         
           
               
               
             
               
                 TABLE 8 
               
             
            
               
                   
               
               
                   
                 Ratio of second original parameter to first 
               
               
                   
                 updated parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Color pattern 
                 X2/X1′ 
                 Y2/Y1′ 
                 Z2/Z1′ 
               
               
                   
               
               
                   
                 White pattern 
                 0.953403 
                 0.952506 
                 0.960586 
               
               
                   
                 W255 
               
               
                   
               
            
           
         
       
     
     In another embodiment, a fourth matrix 
                   [         104.1608         5   ⁢     2   .   7     ⁢   8   ⁢   6   ⁢   3             2   .   7     ⁢   60134             85.04818         17   ⁢     7   .   6     ⁢   2   ⁢   6   ⁢   5           2   ⁢     8   .   5     ⁢   7   ⁢   7   ⁢   3   ⁢   9             48.4418         17.9   ⁢   4   ⁢   8   ⁢   9           2   ⁢   6   ⁢     7   .   6     ⁢   2   ⁢   7   ⁢   9           ]           
may consist of the first updated parameters of the red pattern R255, the green pattern G255 and the blue pattern B255, and a second matrix
 
                   [         98.24092         4   ⁢     9   .   7     ⁢   6   ⁢   3   ⁢   8   ⁢   2             2   .   6     ⁢   5   ⁢   6   ⁢   3   ⁢   6   ⁢   3             81.77143         16   ⁢     9   .   6     ⁢   4   ⁢   3   ⁢   3         27.21642             4   ⁢   6.6137           17.2057   ⁢   2           2   ⁢   5   ⁢     7   .   3     ⁢   841           ]           
may consist of the second original parameters of the red pattern R255, the green pattern G255 and the blue pattern B255. Then, the processing unit  14  may multiply the second matrix by an inverse matrix of the fourth matrix and sets negative value(s) to be zero, so as to obtain a fifth matrix
 
                     [             0   .   9     ⁢   43194         0           0   .   0     ⁢   00215                 0   .   0     ⁢   0   ⁢   6   ⁢   9   ⁢   8   ⁢   7             0   .   9     ⁢   5   ⁢   2   ⁢   9   ⁢   9   ⁢   3         0               0   .   0     ⁢   0   ⁢   0   ⁢   6   ⁢   4   ⁢   7         0           0   .   9     ⁢   61772           ]     .           
Then, the processing unit may take the fifth matrix to be the second gain factor.
 
     If the maximum value 0.962152 in Table 3 is taken to be the second gain factor G2, the first adjusted parameters of each color pattern in the first picture P1 obtained in the step S 20  are shown in Table 9 below. 
     
       
         
           
               
             
               
                 TABLE 9 
               
             
            
               
                   
               
               
                 First picture P1 
               
            
           
           
               
               
            
               
                   
                 First adjusted parameter 
               
            
           
           
               
               
               
               
            
               
                 Color pattern 
                 X1″ = X1′ * G2 
                 Y1″ = Y1′ * G2 
                 Z1″ = Z1′ * G2 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Black pattern 
                 0.246572 
                 0.238487 
                 0.48676 
               
               
                 W0 
                   
                   
                   
               
               
                 White pattern 
                 228.8507 
                 239.1326 
                 287.9402 
               
               
                 W255 
                   
                   
                   
               
               
                 Red pattern 
                 100.2185 
                 50.78846 
                 2.65567 
               
               
                 R255 
                   
                   
                   
               
               
                 Green pattern 
                 81.8293 
                 170.9038 
                 27.4958 
               
               
                 G255 
                   
                   
                   
               
               
                 Blue pattern 
                 46.60839 
                 17.26958 
                 257.4988 
               
               
                 B255 
               
               
                   
               
            
           
         
       
     
     Referring to Table 10 below, Table 10 shows the difference of Y values (brightness values) of the white pattern W255 between the first picture P1 and the second picture P2 before and after adjusting the first picture P1. In Table 10, it is obvious that the brightness difference between the first picture P1 and the second picture P2 can be reduced effectively after adjusting the first picture P1 through the aforesaid method. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 10 
               
               
                   
               
               
                   
                   
                 Before adjusting 
                 After adjusting 
               
               
                   
                   
                 first picture P1 
                 first picture P1 
               
               
                   
                 Color pattern 
                 |Y2 − Y1| 
                 |Y2 − Y1″| 
               
               
                   
               
             
            
               
                   
                 White pattern W255 
                 11.81181 
                 2.397469 
               
               
                   
               
            
           
         
       
     
     Referring to  FIG. 3 ,  FIG. 3  is a flowchart illustrating a picture adjusting method according to another embodiment of the invention. The picture adjusting method shown in  FIG. 3  is also adapted to the display system  1  shown in  FIG. 1 . It should be noted that the step S 22  in  FIG. 3  is performed after the step S 20  shown in  FIG. 2 . 
     After adjusting the brightness of the first picture P1 by the picture adjusting method shown in  FIG. 2 , the invention may further adjust the brightness of the second picture P2 by the picture adjusting method shown in  FIG. 3 . Thus, after the step S 20 , the processing unit  14  may calculate a third gain factor according to the first adjusted parameters and the second original parameters of at least one of the color patterns except the black pattern (step S 22  in  FIG. 3 ). In this embodiment, the processing unit  14  may calculate a ratio of each first adjusted parameter to each second original parameter of at least one of the white pattern W255, the red pattern R255, the green pattern G255 and the blue pattern B255 to obtain a plurality of ratios. Then, the processing unit  14  may take a specific value from the ratios to be the third gain factor, wherein the specific value may be a minimum value, a maximum value, an average value, a median value or other values. As shown in Table 11 below, the processing unit  14  may calculate a ratio of each first adjusted parameter to each second original parameter of the white pattern W255, the red pattern R255, the green pattern G255 and the blue pattern B255 to obtain a plurality of ratios. At this time, the specific value served as the third gain factor may be a minimum value 0.999739, a maximum value 1.02059, an average value 1.006987, a median value 1.005571 or other values in Table 11. 
     
       
         
           
               
               
             
               
                 TABLE 11 
               
             
            
               
                   
               
               
                   
                 Ratio of first adjusted parameter to second 
               
               
                   
                 original parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Color pattern 
                 X1″/X2 
                 Y1″/Y2 
                 Z1″/Z2 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 White pattern 
                 1.009177 
                 1.010127 
                 1.001631 
               
               
                   
                 W255 
                   
                   
                   
               
               
                   
                 Red pattern 
                 1.02013 
                 1.02059 
                 0.999739 
               
               
                   
                 R255 
                   
                   
                   
               
               
                   
                 Green pattern 
                 1.000708 
                 1.00743 
                 1.010265 
               
               
                   
                 G255 
                   
                   
                   
               
               
                   
                 Blue pattern 
                 0.999886 
                 1.003712 
                 1.000446 
               
               
                   
                 B255 
               
               
                   
               
            
           
         
       
     
     In another embodiment, the processing unit  14  may calculate a ratio of each first adjusted parameter to each second original parameter of the white pattern W255 to obtain a plurality of ratios. Then, the processing unit  14  may take a matrix consisting of the ratios to be the third gain factor. As shown in Table 12 below, the matrix served as the third gain factor is [1.009177 1.010127 1.001631]. Needless to say, the processing unit  14  may also take a minimum value, a maximum value, an average value, a median value or other values in Table 12 to be the third gain factor. 
     
       
         
           
               
               
             
               
                 TABLE 12 
               
             
            
               
                   
               
               
                   
                 Ratio of first adjusted parameter to second 
               
               
                   
                 original parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Color pattern 
                 X1″/X2 
                 Y1″/Y2 
                 Z1″/Z2 
               
               
                   
               
               
                   
                 White pattern 
                 1.009177 
                 1.010127 
                 1.001631 
               
               
                   
                 W255 
               
               
                   
               
            
           
         
       
     
     In another embodiment, a sixth matrix 
                   [           10   ⁢   0.2185           5   ⁢     0   .   7     ⁢   8   ⁢   8   ⁢   4   ⁢   6             2   .   6     ⁢   5   ⁢   5   ⁢   6   ⁢   7             81.8293         17   ⁢     0   .   9     ⁢   0   ⁢   3   ⁢   8           2   ⁢     7   .   4     ⁢   9   ⁢   5   ⁢   8               4   ⁢     6   .   6     ⁢   0   ⁢   8   ⁢   3   ⁢   9           17.2   ⁢   6   ⁢   9   ⁢   5   ⁢   8           2   ⁢   5   ⁢     7   .   4     ⁢   9   ⁢   8   ⁢   8           ]           
may consist of the first adjusted parameters of the red pattern R255, the green pattern G255 and the blue pattern B255, and a second matrix
 
                   [         98.24092         4   ⁢     9   .   7     ⁢   6   ⁢   3   ⁢   8   ⁢   2             2   .   6     ⁢   5   ⁢   6   ⁢   3   ⁢   6   ⁢   3             81.77143         16   ⁢     9   .   6     ⁢   4   ⁢   3   ⁢   3           2   ⁢   7.21642               4   ⁢   6.6137           17.2   ⁢   0   ⁢   5   ⁢   7   ⁢   2           2   ⁢   5   ⁢     7   .   3     ⁢   841           ]           
may consist of the second original parameters of the red pattern R255, the green pattern G255 and the blue pattern B255. Then, the processing unit  14  may multiply the sixth matrix by an inverse matrix of the second matrix and sets negative value(s) to be zero, so as to obtain a seventh matrix
 
                     [         1.020099           0   .   0     ⁢   00167         0           0       1.009609           0   .   0     ⁢   00147             0           0   .   0     ⁢   0   ⁢   0   ⁢   5   ⁢   3   ⁢   9         1.000396         ]     .           
Then, the processing unit may take the seventh matrix to be the third gain factor.
 
     In the following, the minimum value 1.001631 in Table 12 is taken to be the third gain factor to illustrate the steps after the step S 22 . After obtaining the third gain factor, the processing unit  14  subtracts a product of the second original parameters of the black pattern W0 and the third gain factor from the first adjusted parameters of the black pattern W0 to obtain a plurality of second offset values (step S 24  in  FIG. 3 ). It is assumed that the third gain factor is represented by G3, so the calculation and result of the second offset values are shown in Table 13 below. 
     
       
         
           
               
               
             
               
                 TABLE 13 
               
             
            
               
                   
               
               
                   
                 Subtract product of second original parameter and 
               
               
                 Black pattern 
                 third gain factor from first adjusted parameter 
               
            
           
           
               
               
               
               
            
               
                 W0 
                 X1″ − X2 * G3 
                 Y1″ − Y2 * G3 
                 Z1″ − Z2 * G3 
               
               
                   
               
               
                 Second offset 
                 −0.00019 
                 −0.000097 
                 −0.00039 
               
               
                 value 
               
               
                   
               
            
           
         
       
     
     Then, the processing unit  14  adds the second offset values to the second original parameters of each color pattern to obtain a plurality of second updated parameters of each color pattern in the second picture P2 (step S 26  in  FIG. 3 ), as shown in Table 14 below. 
     
       
         
           
               
             
               
                 TABLE 14 
               
             
            
               
                   
               
               
                 Second picture P2 
               
            
           
           
               
               
            
               
                   
                 Second updated parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                 X2′ = X2 − 
                 Y2′ = Y2 − 
                 Z2′ = Z2 − 
               
               
                   
                 Color pattern 
                 0.00019 
                 0.000097 
                 0.00039 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 Black pattern 
                 0.24617 
                 0.238098 
                 0.485966 
               
               
                   
                 W0 
                   
                   
                   
               
               
                   
                 White pattern 
                 226.7694 
                 236.735 
                 287.471 
               
               
                   
                 W255 
                   
                   
                   
               
               
                   
                 Red pattern 
                 98.24072 
                 49.76372 
                 2.655973 
               
               
                   
                 R255 
                   
                   
                   
               
               
                   
                 Green pattern 
                 81.77124 
                 169.6432 
                 27.21603 
               
               
                   
                 G255 
                   
                   
                   
               
               
                   
                 Blue pattern 
                 46.61351 
                 17.20562 
                 257.3837 
               
               
                   
                 B255 
               
               
                   
               
            
           
         
       
     
     Then, the processing unit  14  multiplies the second updated parameters of each color pattern by a fourth gain factor to obtain a plurality of second adjusted parameters of each color pattern in the second picture P2 (step S 28  in  FIG. 3 ). In this embodiment, the processing unit  14  may take the aforesaid third gain factor to be the fourth gain factor. 
     In another embodiment, the processing unit  14  may calculate a ratio of each first adjusted parameter to each second updated parameter of at least one of the white pattern W255, the red pattern R255, the green pattern G255 and the blue pattern B255 to obtain a plurality of ratios. Then, the processing unit  14  may take a specific value from the ratios to be the fourth gain factor, wherein the specific value may be a minimum value, a maximum value, an average value, a median value or other values. As shown in Table 15 below, the processing unit  14  may calculate a ratio of each first adjusted parameter to each second updated parameter of the white pattern W255, the red pattern R255, the green pattern G255 and the blue pattern B255 to obtain a plurality of ratios. At this time, the specific value served as the fourth gain factor may be a minimum value 0.999886, a maximum value 1.020592, an average value 1.007002, a median value 1.005574 or other values in Table 15. 
     
       
         
           
               
               
             
               
                 TABLE 15 
               
             
            
               
                   
               
               
                   
                 Ratio of first adjusted parameter to second 
               
               
                   
                 updated parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Color pattern 
                 X1″/X2′ 
                 Y1″/Y2′ 
                 Z1″/Z2′ 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                   
                 White pattern 
                 1.009178 
                 1.010128 
                 1.001632 
               
               
                   
                 W255 
                   
                   
                   
               
               
                   
                 Red pattern 
                 1.020132 
                 1.020592 
                 0.999886 
               
               
                   
                 R255 
                   
                   
                   
               
               
                   
                 Green pattern 
                 1.00071 
                 1.007431 
                 1.010128 
               
               
                   
                 G255 
                   
                   
                   
               
               
                   
                 Blue pattern 
                 0.99989 
                 1.003717 
                 1.000447 
               
               
                   
                 B255 
               
               
                   
               
            
           
         
       
     
     In another embodiment, the processing unit  14  may calculate a ratio of each first adjusted parameter to each second updated parameter of the white pattern W255 to obtain a plurality of ratios. Then, the processing unit  14  may take a matrix consisting of the ratios to be the fourth gain factor. As shown in Table 16 below, the matrix served as the fourth gain factor is [1.009178 1.010128 1.001632]. 
     
       
         
           
               
               
             
               
                 TABLE 16 
               
             
            
               
                   
               
               
                   
                 Ratio of first adjusted parameter to second 
               
               
                   
                 updated parameter 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Color pattern 
                 X1″/X2′ 
                 Y1″/Y2′ 
                 Z1″/Z2′ 
               
               
                   
               
               
                   
                 White pattern 
                 1.009178 
                 1.010128 
                 1.001632 
               
               
                   
                 W255 
               
               
                   
               
            
           
         
       
     
     In another embodiment, a sixth matrix 
                   [           10   ⁢   0.2185           5   ⁢     0   .   7     ⁢   8   ⁢   8   ⁢   4   ⁢   6             2   .   6     ⁢   5   ⁢   5   ⁢   6   ⁢   7             81.8293         17   ⁢     0   .   9     ⁢   0   ⁢   3   ⁢   8           2   ⁢     7   .   4     ⁢   9   ⁢   5   ⁢   8               4   ⁢     6   .   6     ⁢   0   ⁢   8   ⁢   3   ⁢   9           17.2   ⁢   6   ⁢   9   ⁢   5   ⁢   8           2   ⁢   5   ⁢     7   .   4     ⁢   9   ⁢   8   ⁢   8           ]           
may consist of the first adjusted parameters of the red pattern R255, the green pattern G255 and the blue pattern B255, and an eighth matrix
 
                   [         98.24072         4   ⁢     9   .   7     ⁢   6   ⁢   3   ⁢   7   ⁢   2             2   .   6     ⁢   5   ⁢   5   ⁢   9   ⁢   7   ⁢   3             81.77124         169.643   ⁢   2         27.21603           46.61351         17.2056   ⁢   2           257.383   ⁢   7           ]           
may consist of the second updated parameters of the red pattern R255, the green pattern G255 and the blue pattern B255. Then, the processing unit  14  may multiply the sixth matrix by an inverse matrix of the eighth matrix and sets negative value(s) to be zero, so as to obtain a ninth matrix
 
                     [         1.0201           0   .   0     ⁢   00167         0           0       1.009609           0   .   0     ⁢   00148             0           0   .   0     ⁢   0   ⁢   0   ⁢   5   ⁢   3   ⁢   9         1.000397         ]     .           
Then, the processing unit may take the ninth matrix to be the fourth gain factor.
 
     If the ninth matrix 
                   [         1.0201           0   .   0     ⁢   00167         0           0       1.009609           0   .   0     ⁢   00148             0           0   .   0     ⁢   0   ⁢   0   ⁢   5   ⁢   3   ⁢   9         1.000397         ]           
is taken to be the fourth gain factor G4, the second adjusted parameters of each color pattern in the second picture P2 obtained in the step S 28  are shown in Table 17 below.
 
     
       
         
           
               
             
               
                 TABLE 17 
               
             
            
               
                   
               
               
                 Second picture P2 
               
            
           
           
               
               
            
               
                   
                 Second adjusted parameter 
               
            
           
           
               
               
               
               
            
               
                 Color pattern 
                 X2″ = X2′ * G4 
                 Y2″ = Y2′ * G4 
                 Z2″ = Z2′ * G4 
               
               
                   
               
            
           
           
               
               
               
               
            
               
                 Black pattern 
                 0.251119 
                 0.24069 
                 0.486195 
               
               
                 W0 
                   
                   
                   
               
               
                 White pattern 
                 231.3275 
                 239.2028 
                 287.6202 
               
               
                 W255 
                   
                   
                   
               
               
                 Red pattern 
                 100.2154 
                 50.25979 
                 2.664394 
               
               
                 R255 
                   
                   
                   
               
               
                 Green pattern 
                 83.41486 
                 171.3017 
                 27.25195 
               
               
                 G255 
                   
                   
                   
               
               
                 Blue pattern 
                 47.55045 
                 17.51745 
                 257.4885 
               
               
                 B255 
               
               
                   
               
            
           
         
       
     
     Referring to Table 18 below, Table 18 shows the difference of Y values (brightness values) of the white pattern W255 between the first picture P1 and the second picture P2 before and after adjusting the first picture P1 and the second picture P2. In Table 18, it is obvious that the brightness difference between the first picture P1 and the second picture P2 can be further reduced after adjusting the first picture P1 and the second picture P2 through the aforesaid method. 
     
       
         
           
               
               
               
             
               
                 TABLE 18 
               
               
                   
               
               
                   
                 Before adjusting 
                 After adjusting 
               
               
                   
                 first picture P1 and 
                 first picture P1 and 
               
               
                   
                 second picture P2 
                 second picture P2 
               
               
                 Color pattern 
                 |Y2 − Y1| 
                 |Y2″ − Y1″| 
               
               
                   
               
             
            
               
                 White pattern W255 
                 11.81181 
                 0.070171 
               
               
                   
               
            
           
         
       
     
     As mentioned in the above, when displaying two pictures, the invention calculates the gain factors and the offset values according to the color patterns (e.g. black pattern, white pattern, red pattern, green pattern, blue pattern, etc.) in the two pictures and then adjusts the original parameters of each color pattern by the gain factors and the offset values. Accordingly, the invention can reduce brightness difference between the two pictures, such that the user will not feel obvious difference in vision as watching the two pictures. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.