Patent ID: 7760961
Filing Date: 2010-07-20
Classification: G06T,G09G,H04N

Abstract:
1. A method executed by a computer for enhancing the contrast of a digital image, the method comprising: determining, by a computer, a source histogram of pixel luminance values that defines a pixel distribution in a plurality of luminance ranges for the digital image; identifying at least two primitive histograms from a set of primitive histograms that each define a pixel distribution in a plurality of luminance ranges; calculating a weighted sum in which each of the at least two primitive histograms is allocated a weighted value that minimizes a difference between each of the at least two primitive histograms and the source histogram; generating a transfer function that maps input luminance to output luminance in accordance with the calculated weighted sum; and applying, by the computer, the transfer function to the pixel luminance values to enhance the contrast of the digital image, wherein the transfer function is non-linear and applied across each of the luminance ranges represented in the source histogram to modify luminance values along a transfer curve.