63fb46d6_bster_US___Patent_applications__Description
[Patent application number] 20090244560 [Published] 10-01-2009 [Description] 
BACKGROUND SUPPRESSION IN A MULTI-FUNCTION COLOR SCANNING SYSTEM - What is disclosed is a novel system and method for background suppression in the image path. In one example embodiment, an image is scanned and RGB color values generated for each pixel. Each of the pixels is converted into a Lab color space to obtain luminance and chrominance values. A background luminance and a luminance variation are determined for the scanned image. For each pixel, a determination is made whether that pixel is a white pixel or a non-white pixel based. If the pixel is a white pixel, an adjustment chrominance value for that pixel is determined. The value of the chrominance adjustment is modulated as a function of a difference between the white pixel's luminance and the background luminance. The modulated chrominance adjustment is applied to the white pixel. Adjusted and non-adjusted pixels are stored in a memory. A printer controller converts the pixels to an output space.
Xing Li, Webster US - Patent applications