1. A method for emulation of a photolithographic process for generating on a wafer an overall structure that is divided into at least two substructures, the two substructures on the wafer being produced based on two corresponding substructures on at least two masks, the method comprising: generating aerial images of the at least two substructures on the at least two masks, the at least two substructures including at least a first substructure on a first one of the at least two masks and at least a second substructure on a second one of the at least two masks, and at least one of the aerial images being captured with a mask inspection microscope; correcting, by using a processing unit, errors in the at least one aerial image captured with the mask inspection microscope, the errors including aberrations or distortions introduced into the at least one captured aerial image by the mask inspection microscope, in which correcting the errors includes modifying the at least one aerial image to reduce the aberrations or distortions; and overlaying, using the processing unit, the aerial images of the at least two substructures to form an overall aerial image of the overall structure that includes the first and second substructures, in which prior to the overlaying, one of the aerial images has an image of the first substructure but not the second substructure, and another one of the aerial images has an image of the second substructure but not the first substructure, in which the overlaying the aerial images is performed after correcting errors in the at least one aerial image; wherein a resist simulation is performed as an adjustment of the aerial images, and before the overlaying of the aerial images of the at least two substructures, the aerial images are adjusted to the ratio of the doses to be used for the masks in a scanner by multiplying all the intensity values of at least one of the aerial images by a factor.