Patent ID: 7171047

Claim:
A computer-implemented method for recognizing edges in a scanning electron microscope (SEM) digital image, the image having a plurality of pixels with gray-scale values defining features, the method comprising: recognizing edge regions of the features in the SEM digital image by creating a new image in which pixels in the new image corresponding to pixels in the gray-scale image that have a brightness value meeting a predetermined threshold are assigned a first binary value to represent edge regions, while remaining pixels in the new image are assigned a second value to represent both background and internal areas of the features; performing area recognition to distinguish internal feature areas from background areas; detecting edge lines that separate features from background areas and internal feature areas; determining a brightness level of each pixel based on brightness levels of a plurality of pixels within an N×N pixel window surrounding each respective pixel selecting pixels within the SEM image as starting points P[i], i=1 . . . k; and generating a passport vector for each of the starting points P[i] that contains brightness values of different groups of surrounding pixels.