Patent ID: 7986351

Claim:
A method of luma adaptation for digital image processing, comprising: deriving luminance signals from sensor RGB signals representing an image; obtaining a transfer function from the luminance signals, wherein the transfer function comprises a cumulative function of a histogram for the luminance signals; using the transfer function to adjust the sensor RGB signals to adapt the luma of the image; limiting the peak of the histogram by excluding pixel counts per luminance level exceeding a cap, the cap being, for at least one luminance level, determined, at least in part, by the total number of pixels in the image and the total number of luminance levels, and is less than the actual number of pixels at that luminance level in the sensor RGB signals, the cap causing the transfer function to be determined from fewer pixels than are in the image; and modifying a region of the transfer function such that each of the sensor RGB signals in the region is not lighter than its respective adjusted sensor RGB signal, the region of the transfer function modified determined at least in part by the number of excluded pixel counts.