1. A computer-implemented method of increasing contrast of an image, the method comprising: receiving, by a processor, the image in a first color space; determining, by the processor, a color transformation for the image by: mapping pixel color characteristics to a second color space, estimating a color distribution of the image in the second color space, expanding the color distribution in the second color space to obtain an expanded color distribution, and using the expanded color distribution to calculate new pixel color characteristics in the first color space; and the processor using the color transformation to construct a color-expanded image, wherein the color transformation expands the range of colors of at least a portion of the image.