1. A computer-implemented method for enhancing black density of a halftoned bitmap, comprising: receiving a halftoned bitmap into computer memory; using a computer, identifying at least one black-only pixel in the halftoned bitmap; for each of the identified black-only pixels, identifying at least one black-only pixel as a candidate for adding color based at least in part on the location of the black-only pixel with respect to an edge in the halftoned bitmap; modifying the halftoned bitmap by adding color to at least one of the candidate black-only pixels; and outputting the modified halftoned bitmap.