Patent ID: 7825938

Claim:
A method for processing a digital image which is to be displayed on a display panel illuminated with a backlight module, the method comprising the steps of: generating a luminance statistic of said digital image; determining a specific backlight duty according to said luminance statistic; setting said backlight module to said specific backlight duty; forming a tone mapping function according to said specific backlight duty and said luminance statistic; and remapping said digital image by said tone mapping function before said digital image is displayed on said display panel; wherein luminance value of each pixel in said digital image is encoded with a predetermined bit resolution and said forming of a tone mapping function comprises: determining a linear upper limit mapping function having a specific slope R 1 determined according to said specific backlight duty, said linear upper limit mapping function remapping code value zero to zero; determining a first luminance value X 1 according to said specific slope R 1 ; determining a second luminance value X 2 according to said first luminance value X 1 and the maximum code value Cmax in said predetermined bit resolution; determining a lower limit factor R 2 greater than or equal to one, and less than said specific slope R 1 ; and forming said tone mapping function such that said second luminance value X 2 is remapped to a specific remapped value (W*R 1 +(1−W)*R 2 )*X 2 , wherein W is a weighting number lying between 0 and 1 which is determined according to said luminance statistic, and wherein any luminance value less than said first luminance value X 1 is remapped through said linear upper limit mapping function.