A system and method includes reception of a color image comprising a plurality of color pixels, conversion of the color image to a monochromatic image comprising a plurality of monochromatic pixels, performance of M erosion operations on the monochromatic image to generate an eroded monochromatic image, where M is equal to or greater than one, performance of N dilation operations on the eroded monochromatic image to generate a mask image, where N is equal to or greater than one, identification of one or more regions of the mask image based on the mask image, and modification of regions of the color image corresponding to the identified regions of the mask image.