1. A method, executed by at least one processor of a computer, comprising: receiving layout data for one or more layout designs; determining isolated mask feature component diffraction signals associated with individual layout feature components in the one or more layout designs based on a component-based mask diffraction modeling method; determining mask feature component diffraction signals based on the isolated mask feature component diffraction signals, the layout data and predetermined crosstalk signals, wherein the predetermined crosstalk signals are derived based on mask feature component diffraction signals computed using an electromagnetic field solver and the component-based mask diffraction modeling method, respectively; processing the one or more layout designs based on the mask feature component diffraction signals; and storing results of the processed one or more layout designs in a tangible medium.