1. A method for inspecting a photomask to identify lithographically significant defects, the method comprising: providing the photomask comprising one or more printable features and one or more non-printable features, the photomask configured to achieve lithographic transfer of the one or more printable features onto a substrate using a lithography system; producing test light intensity images of the photomask using an inspection apparatus, the test light intensity images comprising a test transmission image and a test reflection image; constructing a band limited mask pattern; providing a model of the lithography system to be employed in the lithographic transfer; constructing an aerial image of the band limited mask pattern by applying the model of the lithography system to the band limited mask pattern, wherein constructing the aerial image comprises separating the one or more non-printable features from the one or more printable features based on optical intensity distributions in the aerial image; building a model-based feature map using the aerial image of the mask pattern, wherein the model-based feature map differentiates between the one or more printable features and the one or more non-printable features; and analyzing the test light intensity images using the model-based feature map to identify any lithographically significant defects.