Abstract: In certain aspects, a quasi-rigorous electromagnetic simulation, such as a domain decomposition-based simulation, is applied to an area of interest of a lithographic mask to produce an approximate prediction of the electromagnetic field from the area of interest. This is then applied as input to a machine learning model, which improves the electromagnetic field prediction from the quasi-rigorous simulation, thus yielding results which are closer to a fully-rigorous Maxwell simulation but without requiring the same computational load.