Patent Publication Number: US-8970788-B2

Title: Gain-determining method and apparatus for grayscale white balance of display apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a method and apparatus of gain-determining and, more particularly, to a gain-determining method and a related apparatus for adjusting the grayscale white balance of a display apparatus. 
     2. Description of the Prior Art 
     With the progress of the technology and art of manufacturing, display apparatuses such as television also evolve continuously. The transition from analog form to digital form allows the application of image signals to be more broad and abounding. The panel for displaying images is also changed from heavy CRT to thin LCD and PDP. In the meanwhile, the size of panels also tends to be larger and larger. When the size of a panel is enlarged, the performance of image resolution of the panel becomes more important. In the performance of color, the saturation of color, the chromatic value, and the luminance are major factors which determine the quality of a display apparatus. 
     The image processing technology nowadays divides the displaying area on the panel into several pixel areas, and every pixel area has a red pixel, a green pixel, and a blue pixel. Because the color of all visible light can be generated by mixing red light, green light, and blue light, a pixel can display the desired color by controlling the light and shade of the red pixel, the green pixel, and the blue pixel. Due to factors such as the material of a panel and its manufacturing process, the color performance of every display apparatus is different. after assembling. In order to keep the color performance correct and uniform before exporting, the grayscale white balance of every display apparatus must be adjusted. 
     The adjusting method of grayscale white balance is: first, display a white image on the display apparatus; then, adjust the gains of sharpness of red color, green color, and blue color to make the chromatic values and luminance of the white image, obtained by mixing the three colors, approach the chromatic values and luminance of a target white image, that is to adjust the white image within a certain range of color temperature and color differences. 
     In prior art, the adjusting of grayscale white balance is mostly achieved by adjusting the gains of the sharpness of the red color, green color, and blue color by hand. However, adjusting by hand wastes a lot of time; at the same time, the difference between operations of people makes it difficult to achieve uniform quality of each product. Due to these defects in the prior art, the inventor provides the invention to improve the adjusting process for promoting the manufacturing capability and quality. 
     SUMMARY OF THE INVENTION 
     Accordingly, one scope of the invention is to provide a gain-determining apparatus for grayscale white balance of a display apparatus. The gain-determining apparatus adjusts the gains of sharpness of red color, green color, and blue color by automatically measuring to save working time and to promote the manufacturing capability of display apparatuses. 
     Another scope of the invention is to provide a gain-determining method for grayscale white balance of a display apparatus. The gain-determining method generates the gains of sharpness of red color, green color, and blue color by automatically measuring to achieve higher unity and to promote the quality of display apparatuses. 
     According to a gain-determining apparatus of a preferred embodiment of the invention, the gain-determining apparatus applies to a display apparatus which includes a panel. The display apparatus is able to respectively display a full red image, a full green image, a full blue image, and a full white image on the panel. The full white image is formed by mixing the full red image, the full green image, and the full blue image. The chromatic values and the luminance of the full white image, the full red image, the full green image, and the full blue image displayed on the panel can all be measured respectively. 
     The gain-determining apparatus includes a first receiving module, a second receiving module, a third receiving module, a fourth receiving module, a fifth receiving module, a first calculating module, a second calculating module, and a third calculating module. The first receiving module is configured to receive the measured chromatic values and the measured luminance of the full white image. The second receiving module is configured to receive the measured chromatic values and the measured luminance of the full red image. The third receiving module is configured to receive the measured chromatic values and the measured luminance of the full green image. The fourth receiving module is configured to receive the measured chromatic values and the measured luminance of the full blue image. The fifth receiving module is configured to receive the inputting of chromatic values and luminance of a target white image. The first calculating module is configured to calculate a first set of color mixture ratios in accordance with the measured chromatic values and the measured luminance of the full white image, the full red image, the full green image, and the full blue image with a law of color mixture. The second calculating module is configured to calculate a second set of color mixture ratios in accordance with the chromatic values and the luminance of the target white image, the measured chromatic values and the measured luminance of the full red image, the full green image, and the full blue image with the law of color mixture. The third calculating module is configured to calculate a red gain, a green gain, and a blue gain in accordance with the first set of color mixture ratios and the second set of color mixture ratios. 
     The above-mentioned law of color mixture is the Grassmann&#39;s law of color mixture. 
     According to a gain-determining method of a preferred embodiment of the invention, the gain-determining method is suitable for grayscale white balance of a display that includes a panel. First, the gain-determining method displays a full white image on the panel of the display apparatus and measures chromatic values and luminance of the full white image displayed on the panel, wherein the full white image is formed by mixing a full red image, a full green image, and a full blue image. Then, the gain-determining method displays the full red image on the panel of the display apparatus and measures chromatic values and luminance of the full red image displayed on the panel. Next, the gain-determining method displays the full green image on the panel of the display apparatus and measures chromatic values and luminance of the full green image displayed on the panel. Then, the gain-determining method displays the full blue image on the panel of the display apparatus and measures chromatic values and luminance of the full blue image displayed on the panel. Furthermore, the gain-determining method inputs chromatic values and luminance of a target white image. Then, the gain-determining method calculates a first set of color mixture ratios in accordance with the measured chromatic values and the measured luminance of the full white image, the full red image, the full green image, and the full blue image with a law of color mixture. Then, the gain-determining method calculates a second set of color mixture ratios in accordance with the chromatic values and the luminance of the target white image, the measured chromatic values and the measured luminance of the full red image, the full green image, and the full blue image with the law of color mixture. Finally, the gain-determining method calculates a red gain, a green gain, and a blue gain in accordance with the first set of color mixture ratios and the second set of color mixture ratios. 
     The advantage and spirit of the invention may be understood by the following recitations together with the appended drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE APPENDED DRAWINGS 
         FIG. 1  is a schematic diagram illustrating an infrastructure of a gain-determining apparatus for grayscale white balance of a display apparatus of a preferred embodiment of the invention. 
         FIG. 2  is a process flow chart showing a gain-determining method of the gain-determining apparatus of the preferred embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention provides a gain-determining method and a gain-determining apparatus for grayscale white balance of a display apparatus. 
     Referring to  FIG. 1 ,  FIG. 1  is a schematic diagram illustrating an infrastructure of a gain-determining apparatus  1  for grayscale white balance of a display apparatus  2  of a preferred embodiment of the invention. The gain-determining apparatus  1  determines a red gain, a green gain, and a blue gain in a grayscale white balance adjusting process of a display apparatus  2 , so as to respectively adjust the sharpness of the red color, the sharpness of the green color, and the sharpness of the blue color. 
     As shown in  FIG. 1 , the display apparatus  2  includes a panel  21 , a sharpness gaining module  22 , a memory  23 , an image processing module  24 , and an image source  25 . The memory  23  is for storing a red gain, a green gain, and a blue gain. The image processing module  24  is for proceeding image processing procedures (such as decoding) on the image signals transmitted by the image source  25 . The sharpness gaining module  22  adjusts the gain of sharpness of the image signals of the red color, the green color, and the blue color transmitted by the image processing module  24  according to the red gain, the green gain, and the blue gain. The sharpness-gained signals are then transmitted to the panel  21  to display. 
     According to a law of color mixture (referring to the Grassmann&#39;s law of color mixture), all colors of light can be generated by mixing red light, green light, and blue light in accordance with specific color mixture ratios. The inventor of the invention utilizes color mixture ratios and automatic measuring technology to improve the adjusting process for grayscale white balance of the display apparatus  2 . The chromatic values and the luminance of the full white image, the full red image, the full green image, and the full blue image displayed on the panel  21  of the display apparatus  2  can first be measured, and then a first set of color mixture ratios in accordance with the measured chromatic values and the measured luminance of the full white image, the full red image, the full green image, and the full blue image can be calculated. Then, a second set of color mixture ratios can be calculated in accordance with the chromatic values and the luminance of the target white image, the measured chromatic values and the measured luminance of the full red image, the full green image, and the full blue image. Finally, a red gain, a green gain, and a blue gain are calculated in accordance with the first set of color mixture ratios and the second set of color mixture ratios, and the red gain, the green gain, and the blue gain are inputted to the memory  23  of the display apparatus  2 . 
     Thereupon, the concept of the invention will be illustrated in figures. The display apparatus  2  in  FIG. 1  is able to respectively display a full red image, a full green image, a full blue image, and a full white image on the panel  21 . The full white image is formed by mixing the full red image, the full green image and the full blue image. A measuring apparatus  3 , which is used for measuring optical properties such as chromatic values and the luminance, in  FIG. 1  is an optical measuring instrument. When the panel  21  displays the full white image, the full red image, the full green image and the full blue image, the measuring apparatus  3  retrieves the images and inputs the chromatic values and the luminance of the retrieved images into the gain-determining apparatus  1 . 
     As shown in  FIG. 1 , the gain-determining apparatus  1  has a first receiving module  11 , a second receiving module  12 , a third receiving module  13 , a fourth receiving module  14 , a fifth receiving module  15 , a first calculating module  16 , a second calculating module  17 , and a third calculating module  18 . 
     The first receiving module  11 , the second receiving module  12 , the third receiving module  13 , and the fourth receiving module  14  are electrically configured to the measuring apparatus  3 . The first receiving module  11  is for receiving the chromatic values and the luminance of the full white image. The second receiving module  12  is for receiving the chromatic values and the luminance of the full red image. The third receiving module  13  is for receiving the chromatic values and the luminance of the full green image. The fourth receiving module  14  is for receiving the chromatic values and the luminance of the full blue image. The fifth receiving module  15  is for receiving the chromatic values and the luminance of a target white image inputted by a setting source  151 . 
     The first calculating module  16  calculates a first set of color mixture ratios in accordance with the measured chromatic values and the measured luminance of the full white image, the full red image; the full green image, and the full blue image with the law of color mixture mentioned above. The first set of color mixture ratios (m rp , m gp , m Bp ) is represented as formula (1):
 
 W   p   =m   rp   R   p   +m   gp   G   p   +m   bp   B   p   (1)
 
     Formula (1) represents that a unit of intensity of the full white image W P  can be generated by mixing m rp  unit of intensity of red image R P , m gp  unit of intensity of green image G P , and m Bp  unit of intensity of blue image B P . Formula (1) derived from the chromatic values and the luminance of color images is from prior art, so there will not be any more discussion. 
     The second calculating module  17  calculates a second set of color mixture ratios in accordance with the chromatic values and luminance of the target white image, the measured chromatic values and the measured luminance of the full red image, the full green image, and the full blue image with the law of color mixture. The second set of color mixture ratios (m ri , m gi , m Bi ) is represented as formula (2):
 
 W   i   =m   ri   R   p   +m   gi   G   p   +m   bi   B   p   (2)
 
     Formula (2) represents that a unit of intensity of target white image W i  can be generated by mixing m ri  unit of intensity of red image R P , m gi  unit of intensity of green image G P , and m bi  unit of intensity of blue image B P . 
     According to formula (1) and (2), if we want to adjust W P  in formula (1) to equal W i  in formula (2), the red image R P , the green image G P , and the blue image B P  in formula (1) need to be respectively multiplied by a red gain c r , a green gain c g , and a blue gain c b . Then formula (3) can be derived as follows:
 
 W   i   =c   r   m   rp   R   p   +c   g   m   gp   G   p   +c   b   m   bp   B   p   (3)
 
     Formula (4), (5), and (6) can also be derived as follows: 
     
       
         
           
             
               
                 
                   
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                       m 
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                       m 
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                   4 
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                     c 
                     g 
                   
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                       m 
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                       m 
                       gp 
                     
                   
                 
               
               
                 
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                   5 
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                     c 
                     b 
                   
                   = 
                   
                     
                       m 
                       bi 
                     
                     
                       m 
                       bp 
                     
                   
                 
               
               
                 
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                   6 
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     The third calculating module  18  calculates a red gain c r , a green gain c g , and a blue gain c b  by substituting the first set of color mixture ratios (m rp , m gp , m bp ), which is calculated by the first calculating module  16 , and the second set of color mixture ratios (m ri , m gi , m bi ), which is calculated by the second calculating module  17 , into formula (4), (5), and (6). The third calculating module  18  then outputs the results to the memory  23  of the display apparatus  2 . 
     Furthermore, for the benefit of the processes of digital circuit, the third calculating module  18  digitizes the red gain c r , the green gain c g , and the blue gain c b  before outputting the results. In the first step, the third calculating module  18  normalizes the gains of the three colors in accordance with the largest value of the red gain c r , the green gain c g , and the blue gain c b . Then, the third calculating module  18  enlarges the normalized gains of the three colors with a power of 2. 
     Subsequently, referring to  FIG. 2 ,  FIG. 2  is a process flow chart showing a gain-determining method  5  of the gain-determining apparatus  1  of the preferred embodiment of the invention. Please refer to  FIG. 1  and formula (1) to formula (6) the related infrastructure, elements, and formulas. As shown in  FIG. 2 , the gain-determining method  5  includes the following steps. 
     First, the display apparatus  2  displays a full white image on the panel  21 . At the same time, the measuring apparatus  3  measures the chromatic values and the luminance of the full white image, wherein the full white image is formed by mixing a full red image, a full green image, and a full blue image (step S 50 ). 
     Then, the display apparatus  2  displays the full red image on the panel  21 . At the same time, the measuring apparatus  3  measures the chromatic values and the luminance of the full red image (step S 51 ). 
     Next, the display apparatus  2  displays the full green image on the panel  21 . At the same time, the measuring apparatus  3  measures the chromatic values and the luminance of the full green image (step S 52 ). 
     Then, the display apparatus  2  displays the full blue image on the panel  21 . At the same time, the measuring apparatus  3  measures the chromatic values and the luminance of the full blue image (step S 53 ). 
     Furthermore, the chromatic values and the luminance of a target white image are inputted (step S 54 ). 
     Then, a first set of color mixture ratios (m rp , m gp , m bp ) are calculated in accordance with the measured chromatic values and the measured luminance of the full white image, the full red image, the full green image, and the full blue image with a law of color mixture (step S 55 ). 
     Next, a second set of color mixture ratios (m ri , m gi , m bi ) are calculated in accordance with the chromatic values and the luminance of the target white image, the measured chromatic values and the measured luminance of the full red image, the full green image, and the full blue image with the law of color mixture (step S 56 ). 
     Finally, a red gain c r , a green gain c g , and a blue gain c b  are calculated in accordance with the first set of color mixture ratios (m rp , m gp , m bp ) and the second set of color mixture ratios (m ri , m gi , m bi ) (step S 57 ). 
     After the step S 57  of the above-mentioned gain-determining method  5 , the red gain c r , the green gain c g , and the, blue gain c b  are immediately inputted into the display apparatus  2 . 
     In the above-mentioned gain-determining method, the law of color mixture is the Grassmann&#39;s law of color mixture. 
     Accordingly, the gain-determining apparatus and the gain-determining method for grayscale white balance of a display apparatus provided by the invention are able to automatically measure gains of red color, green color, and blue color. By the way, the working time can be saved and the manufacturing capability of display apparatuses can be promoted. At the same time, the unity of the features of products can be improved, and the qualities of display apparatuses are enhanced. 
     With the example and explanations above, the features and spirits of the invention will be hopefully well described. Those skilled in the art will readily observe that numerous modifications and alterations of the device may be made while retaining the teaching of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.