| 摘要 |
<p>A method for checking a mark comprises the steps of: converting an image signal for pixels to digital signals each corresponding to densities, detecting a maximum value and a minimum value, respectively, of image signal densities of a noted pixel and one or more pixels around the noted pixel, binary converting the noted pixel using a threshold selected as a medium value between the maximum and minimum values detected, extracting respective characteristic quantities of a plurality of independent patterns which are separate from each other in a standard image; defining a relative coordinate system based on respective positions of center of gravitation of two independent patterns which can be defined by different characteristic quantities; registering respective positions of center of gravitation of and respective characteristic quantities of the plurality of independent patterns, respectively, in the relative coordinate system; collating the independent patterns in the objective image with the independent patterns in the standard image; and comparing characteristic quantities between corresponding patterns to discriminate defects of the mark, if any.</p> |
