Patent ID: 8260078

Claim:
A non-transitory computer-readable medium including instructions that, when executed by a processing unit, cause the processing unit to sharpen a digital image that is H pixels in height and W pixels in width, by performing the steps of: generating a plurality of luminance values for a portion of the digital image, wherein each luminance value corresponds to a different pixel location in the portion of the digital image; generating a plurality of sharpened luminance values for the portion of the digital image by applying a sharpening filter to one or more of the luminance values, wherein each sharpened luminance value corresponds to a different pixel location in the portion of the digital image; and generating a sharpened digital image for output to a display or for storage in a memory by selecting, for each pixel location in the portion of the digital image, either the luminance value in the plurality of luminance values corresponding to the pixel location or the sharpened luminance value in the plurality of sharpened luminance values corresponding to the pixel location based on a value in an alpha mask corresponding to the pixel location, wherein the alpha mask is derived from at least one of, an overshoot alpha submask, a fringe alpha submask, and a dark alpha submask.