Patent ID: 7822288

Claim:
A method for converting one or more pixels of an input digital image into one or more pixels of an output digital image using a computer comprising a processor and memory comprising the steps of: determining a first histogram of pixel values for pixels in a first region of said input digital image using said processor and storing said first histogram in said memory; determining a second histogram of pixel values for pixels in a second region of said digital input image using said processor and storing said second histogram in said memory, said second region comprising an additive region adjacent to said first region for which a positive value is added to said second histogram for each pixel in said additive region and a subtractive region that coincides with a portion of said first region for which a negative value is added to said second histogram stored in said memory for each pixel in said subtractive region; deriving a third histogram of pixel values for pixels in a third region of said digital input image by combining said first and second histograms using said processor and storing said third histogram in said memory; extracting a rank order pixel value from said third histogram stored in said memory using said processor; creating an output pixel of said output digital image comprising said extracted rank order pixel value using said processor and storing said output pixel in said memory.