| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a defect detection method for performing detection and classification on injurious defects by using an effective feature quantity with respect to local frequency of a luminance signal and directionality of the spread of a defect. <P>SOLUTION: This defect detection method for detecting a defect developed on a surface of an industrial product by an optical method is characterized by dissolving an image signal acquired by imaging into multiple resolution components by two-dimensional wavelet transform, previously selecting multiple resolution components corresponding to the characteristics of the defect to restore images by two-dimensional inverse wavelet transform, and selectively extracting images of defective and non-defective elements each having an intrinsic local frequency and an intrinsic shape. Edges of a steel sheet can be detected by binarizing the restored images and extracting linear factors by means of Hough transform. Different combinations of the resolution components and the number of remaining pixels of the binarized images can be used. Further, defects can be classified by applying a maximum likelihood determination method to the number of remaining pixels. <P>COPYRIGHT: (C)2004,JPO |
