Patent US 6,038,335

A flaw detection apparatus detects a flaw formed on an object's surface based on a digital image data indicative of said object's surface as regions which are groups of plural pixels utilizing the image processing technique. An image processor is provided for detecting an extending direction in which each region extends based on a contour line of each region, so that regions extending in the same direction are clustered as one region. The image processor further produces a flaw signal indicating sizes of thus clustered regions.