| abstract |
Method and apparatus for automatic optical inspection of a substantially two-dimensional pattern using digital image processing techniques are described. In a first processing step, all regions of a digitized stored image derived from the two-dimensional pattern are scanned for edges or lines, that is, transitions between regions having optically different characteristics. The scanned edge regions are marked in the image storage. In a subsequent second processing step all non-marked regions of the image storage are scanned and tested for the presence of permissible grey levels. A meander-shaped scanning track is used for scanning the edge or lined regions. The apparatus for implementing this method includes special latch circuitry for eliminating the further processing of marked regions, thus increasing the overall speed at which the two-dimensional pattern can be optically inspected. |