1. A system, comprising: an interface that receives a color defined by a first coordinate in a first Cyan, Magenta, Yellow, and Key black (CMYK) color space; a color management unit that converts the color to a second coordinate for a second CMYK color space having a black level that matches the black level of the color by selecting a set of points, in the second CMYK color space, that are sampled to cover an entire range of black values in the second CMYK color space and luminosity values in a perceptual color space, determines a location in the perceptual color space for each of the first coordinate and the second coordinate, identifies a distance between the locations in the perceptual color space, and reduces the distance in the perceptual color space between the two locations by iteratively revising the second coordinate in the second CMYK color space while holding the black level of the second coordinate constant.