Patent ID: 7843616

Claim:
A method for background suppression in a multi-function color scanning system, the method comprising: scanning an image into a plurality of pixels; generating RGB color values for each of said pixels; converting said RGB color values for each of said pixels into a Lab color space to obtain a luminance value L, and chrominance values a and b for each pixel; determining a background luminance, backgroundL, of said scanned image; determining whether a pixel is a white pixel or a non-white pixel based on said pixel's luminance and chrominance values; in response to said pixel being a white pixel: determining, for each of said white pixel's chrominance a and b values, a chrominance adjustment value, a out and b out , respectively; determining a difference between said white pixel's luminance value and said background luminance, comprising: k =max(0,background L−L ); modulating each of said chrominance adjustment values by said determined difference to obtain adjustA and adjustB, comprising: adjust A =( a out *ModulationTable2 [k]+ 8)>>4; adjust B =( b out *ModulationTable2 [k]+ 8)>>4; and applying said adjustA and adjustB to said white pixel's chrominance values a and b, respectively; and converting adjusted and non-adjusted pixels to an output space.