Method of eliminating color cast of image in photographic device

Abstract

A method of eliminating a color cast of image in photographic device includes: obtaining a color cast image; determining a color temperature of the color cast image; analyzing a brightness ratio among a first primary color, a second primary color, and a third primary color of the color cast image; choosing one parameter group from a plurality of color cast calibration parameter groups according to the color temperature; calibrating the brightness ratio among the first primary color, the second primary color, and the third primary color of the color cast image via the chosen color cast calibration parameter group.

What is claimed is: 
     
       1. A method of eliminating a color cast of an image in a photographic device including:
 obtaining a color cast image via the photographic device; 
 determining a color temperature of the color cast image; 
 analyzing a brightness ratio among a first primary color, a second primary color, and a third primary color of the color cast image; 
 choosing one parameter group from a plurality of color cast calibration parameter groups according to the color temperature; 
 calibrating the brightness ratio among the first primary color, the second primary color, and the third primary color of the color cast image via the chosen color cast calibration parameter group; and 
 getting the color cast calibration parameter groups at different color temperatures, including:
 getting a plurality of with-color-cast calibration images of a color cast calibration component at different color temperatures; 
 analyzing a brightness ratio among the first primary color, the second primary color, and the third primary color of each of the with-color-cast calibration images; 
 getting a plurality of without-color-cast calibration images of the color cast calibration component at different color temperatures; 
 analyzing the brightness ratio among the first primary color, the second primary color, and the third primary color of each of the without-color-cast calibration images; and 
 comparing the brightness ratio between the with-color-cast calibration images and the without-color-cast calibration images according to different color temperatures to get the color cast calibration parameter groups, respectively. 
 
 
     
     
       2. The method of eliminating a color cast of an image according to  claim 1 , wherein the step of analyzing the brightness ratio of the color cast image includes:
 obtaining a first brightness ratio between the first primary color and the second primary color; and 
 obtaining a second brightness ratio between the third primary color and the second primary color. 
 
     
     
       3. The method of eliminating a color cast of an image according to  claim 2 , wherein the chosen color cast calibration parameter group includes:
 a first calibration parameter used for calibrating the first brightness ratio; and 
 a second calibration parameter used for calibrating the second brightness ratio. 
 
     
     
       4. The method of eliminating a color cast of an image according to  claim 1 , wherein the first primary color is red, the second primary color is green, and the third primary color is blue. 
     
     
       5. The method of eliminating a color cast of an image according to  claim 1 , wherein the color cast calibration parameter groups at a same color temperature includes:
 a first calibration parameter, wherein the first calibration parameter is in proportion to the brightness ratio between the first primary color and the second primary color of the without-color-cast calibration images, and the first calibration parameter is in inverse proportion to the brightness ratio between the first primary color and the second primary color of the with-color-cast calibration images; and 
 a second calibration parameter, wherein the second calibration parameter is in proportion to the brightness ratio between the third primary color and the second primary color of the without-color-cast calibration images, and the second calibration parameter is in inverse proportion to the brightness ratio between the third primary color and the second primary color of the with-color-cast calibration images. 
 
     
     
       6. The method of eliminating a color cast of an image according to  claim 1 , wherein the color cast calibration component is a grey card or a white card. 
     
     
       7. The method of eliminating a color cast of an image according to  claim 1 , further comprising:
 fitting a color cast calibration parameter group of a first color temperature and a color cast calibration parameter group of a second color temperature to get at least one color cast calibration parameter group between the first color temperature and the second color temperature. 
 
     
     
       8. The method of eliminating a color cast of an image according to  claim 7 , wherein the step of fitting is a linear fitting.