1. A computer-implemented method, comprising: obtaining a request associated with screen printing an image on a product, the request comprising a source image and a key color value indicating a number of ink colors for use in the screen printing; computationally determining a set of key colors equal in size to the key color value by: filtering the image so that a plurality of contiguous color areas that are close in color space are preserved, determining a plurality of candidate colors for the plurality of contiguous color areas, and grouping the plurality of contiguous color areas into a number of groups equal in size to the key color value based on the plurality of candidate colors; transforming the source image to at least one destination image that is usable in the screen printing of the product using ink colors based on the set of key colors; wherein the method is performed by one or more processors.