the modifications resulting in distorting features on the wafer further if one only compares an actual mask with a particular opced mask design layout some final wafer pattern fidelity problems caused by other variables in the photolithography process may not be identified the present disclosure provides an improved method and system for evaluating the mask quality and the effectiveness of the opc models fig1 illustrates a general process 100 for conducting a mask pattern fidelity inspection according to one example of the present disclosure starting from a mask design in a database a selected opc model is applied to make a mask through an actual mask making process step 102 a graphical image of the physical mask is obtained in step 104 through a selected standard tool such as a critical dimension scanning electron microscope cdsem the graphical image whatever the format it is in may be referred to generally as a mask picture through the assistance of available standard software the mask picture derived from the physical mask can then be converted into a simulation required digital file in step 106 such as a gds file this simulation required digital file may be referred to simply as a u201c mask based simulation file u201d a simulation is conducted using this simulation file under a set of predetermined photolithography process conditions step 108 the result of the simulation will render certain two dimensional and three dimensional wafer resist profile images in addition if desired an aerial image is also obtainable to represent the wafer resist profile the wafer.