Method and apparatus for detecting extended defects in an object

摘要

A method and apparatus is provided that detects extended defects in a surface, by detecting connected features and classifying the connected features so as to identify defects. A method and apparatus is described which processes an image for edges, thresholds the edge and then determines whether the edges are connected features by examining the orientation of the edges compared to their neighboring edges. Application of the method to read/write heads in a storage-drive assembly application is disclosed. Particular enhancements of the method and apparatus for that application are described, including classifying the defects on a head based on their relationship to the boundary of the head, and applying hysteresis thresholding or diffusion to identify cracks which interfere with the function of the heads.