Patent Document ID: 5553168
Application ID: 08185610
Patent Status: 1

Claim One:
1. A method of identifying visual characters against a noisy background on a semiconductor wafer comprising the steps of; capturing a video image of a scope-of-view window containing the characters; converting the video image to a digital image by using a video-to-digital converter; isolating the visual characters on the digital image; converting the visual characters to image primitives; comparing the image primitives for each character to a plurality of sets of grammar primitives in a grammar database containing known characters to determine the known character whose grammar primitives are least different from the image primitives of each character; and identifying each visual character with the known character whose grammar primitives were least different from the image primitives, wherein the characters comprise a predetermined number of SEMI font characters and wherein the step of isolating the visual character on the digital image comprises the steps of: determining the upper left corner (X.sub.0, Y.sub.0) of the character by: determining the marginal distribution F.sub.y relative to the vertical axis of the scope-of-view window (0.ltoreq.x.ltoreq.n; 0.ltoreq.y=m) where the visual image is Y=f(x,y); determining the marginal distribution F.sub.x relative to the horizontal axis of the scope-of-view window; determining the minimum value of F.sub.x over the scope-of-view window and equating X.sub.0 with the minimum value of F.sub.x ; and determining the maximum value of F.sub.y' over the scope-of-view window where F.sub.y, =dF.sub.y (y)/dy and equating Y.sub.0 with the y value at that point; and creating a character window for each character with the left upper corner of the character window located at (X.sub.0, Y.sub.0).