Patent ID: 7636496

Claim:
A method of automatic mapping of image data comprising: representing image data for an image as luminance values; determining a key value as a function of an average luminance value of the image and of minimum and maximum luminance values of the image; generating offset-adjusted luminance values including applying an offset to each of the luminance values, the offset being a function of the determined key value the luminance L being normalized according to the equation: D = log ⁡ ( L + offset ) - log ⁡ ( L min + offset ) log ⁡ ( L max + offset ) - log ⁡ ( L min + offset ) where L min is the minimum luminance value in the image and L max is the maximum luminance value in the image; and computing a tone reproduction curve for at least a region of the image which includes applying a mapping function to the offset-adjusted luminance values.