1. A computer-implemented method for detecting defects in reticle design data, comprising: using a computer system to perform steps of: generating a first simulated image illustrating how the reticle design data will be printed on a reticle using a reticle manufacturing process; generating second simulated images using the first simulated image, wherein the second simulated images illustrate how the reticle will be printed on a wafer at different values of one or more parameters of a wafer printing process; and detecting defects in the reticle design data using the second simulated images without fabricating the reticle.