1. A computer-implemented method comprising: mapping one or more pieces of artwork of an illustration, the one or more pieces of artwork having a degree of transparency onto a grid; mapping at least a portion of an opaque piece of artwork onto the grid; determining whether the mapping of the opaque piece of artwork includes a grid cell included in the mapping of the one or more pieces of artwork having a degree of transparency; and based on the determining, excluding at least a portion of the opaque artwork from a flattening of at least some of the pieces of artwork, wherein the excluding is performed by one or more processors.