| 摘要 |
PURPOSE:To enable pattern defects to be surely detected even if reference image data deviate from check image data in position by a method wherein the differential direction of the differentially processed image data whose differential value is the smallest of those of all differentially processed image data of a second differential processing means is detected, and the differentially processed image data of a first differential processing means in the differential direction concerned is compared with a threshold value to judge that a pattern is defective or not. CONSTITUTION:Check image data are differentiated in directions of X, Y, and + or -45 deg. through a first differential processing circuit 20, reference image data are differentiated in directions of X, Y, and + or -45 deg., the differential direction of the differentially processed image data whose differential value is the smallest of those of all differentially processed image data of the reference image data is detected, and the differentially processed image data of the check image data in the differential direction concerned is selected. The selected differentially processed image data is compared with a threshold value S10 to judge that a pattern is defective or not. By this setup, the differentially processed image data of reference image data the smallest in differential value becomes zero in differential value, so that only a defective pact is made to appear when the check image data are differentiated in the differential direction concerned. Therefore, even if a reference image data pattern deviates from a check image data pattern in position, defects can be surely detected. |
