Patent Document ID: 7495696
Application ID: 11104076
Patent Status: 1

Claim One:
1. A white balance method for an image formed by a digital still camera, comprising steps of: (a) removing a color cast over a white object of said image, wherein the step (a) includes sub-steps of: storing an original image data I org (R org , G org , B org ) of said image; performing a histogram equalization for said original image data I org ; and converting said original image data I org from an RGB color space to a YC r C b color space so as to obtain a histogram-equalized image data I Hist (Y Hist , C rHist , C bHist ); (b) detecting a reference white point from said image by extracting a pixel information of said white object, wherein the step (b) includes sub-steps of: determining all candidate white pixels from said histogram-equalized image data I Hist with an equation (1): 
 Y Hist ≧210, and 
 −3≦C rHist , C bHist ≦+3  (1); obtaining a relatively brightest pixel (Y Hist bright , C rHist bright , C bHist bright ) from said candidate white pixels, wherein said relatively brightest pixel has a relatively maximum Y Hist value and has C rHist and C bHist values being relatively closest to zero; calculating an average pixel (Y Hist avg , C rHist avg , C bHist avg ) of said candidate white pixels; determining all reference white pixels from said RGB color space if corresponding pixels thereof from said histogram-equalized image data I Hist satisfy equation (2): 
 Y 1 ≦Y Hist ≦Y u 
 C r1 ≦C r Hist ≦C ru 
 C b1 ≦C b Hist ≦C bu (2), wherein Y l and Y u are a relatively maximum value and a relatively minimum value of said Y Hist bright and said Y Hist avg respectively, C rl and C cu are a relatively maximum value and a relatively minimum value of said C rHist bright and said C rHist avg respectively, and C bl and C bu are a relatively maximum value and a relatively minimum value of said C bHist bright and said C bHist avg respectively; and calculating an average W(R w ,G w ,B w ) of said reference white pixels as said pixel information; and (c) adjusting a white balance of said white object by determining a scale factor based on said color cast and said pixel information.