Patent ID: 7406210

Claim:
A method for processing a digital image to alter the darkness thereof, comprising: isolating regions of the digital image wherein said regions include a plurality of image areas, said regions including those suitable for altering the darkness thereof, and extracting image data therefrom for the areas in at least one of said regions, wherein isolating regions of the digital image including those suitable for altering the darkness further includes applying extracted data from said region to a plurality of chained look-up tables to determine if a matching entry is present, wherein the look-up tables include, a first stage where a pseudo-gray look-up table summarizes a plurality of corners of the region into pseudo-gray values, a second stage where top, bottom, left, and right look-up tables summarize the binary patterns that surround a center imaging area, a third stage, where outputs from the second stage are used to compute at least one gradient; merging the gradient with data representing the center imaging area to produce a lightness/darkness signal, and in a fourth stage, implementing a state machine in the form of a propagation look-up table, where the state of the machine is a function of the previous state and the output from the third stage to produce an encoded binary value; using the extracted image data for said region, producing modified image data by modifying data associated with at least one area in the region to alter the darkness of said region; and merging the modified image with the digital image to produce an output digital image having at least one region in which the darkness of the image is altered.