| 摘要 |
PURPOSE:To identify the kinds of defects and perform judgement of defect harmful rate by considering power spectrum distribution in frequency space. CONSTITUTION:The image of a defect is formed in an image pickup part 45 by an optical system 44 and is converted to an electric signal 4a which is then sent to a signal processing part 46. In the signal processing part 46, it undergoes necessary preprocessing such as mean value, trend removal, etc. for the defect image information, after which two-dimensional Fourier transformation processing is accomplished. The output 4b of the signal processing part 46 is the frequency space image corresponding to the defect image and the characteristic parameters DFw, DFr, Rw, Rr having beforehand been selected based on this two-dimensional spectrum distribution pattern are operated. The signal 4c of the magnitude thereof is then outputted to respective level discrimination parts 48. In a defect judgement part 49, the kind and size of the defect are judged from the mutual relationship of the levels of the respective parameters. |
