Provided is a method for fabricating a semiconductor device including generating an ideal image using measured contour data and fitted conventional model terms. The method further includes using the fitted conventional model terms and a mask layout to provide a conventional model aerial image. In some embodiments, the method further includes generating a plurality of mask raster images using the mask layout, where the plurality of mask raster images is generated for each measurement site of the measured contour data. In various embodiments, the method also include training a neural network to mimic the ideal image, where the generated ideal image provides a target output of the neural network, and where the conventional model aerial image and the plurality of mask raster images provide inputs to the neural network.