| 摘要 |
PURPOSE:To obtain a stable binarized output signal by enabling automatic operation without operator's adjustment, by automatically correcting the variation of a signal without receiving restriction from an apparatus or a subject. CONSTITUTION:From video signal input S1, the max. value corresponding to a copper foil level is detected by a detector 1 and the min. value corresponding to a base material level is detected by a detector 2 and the arbitrary intermediate value of the signals from both of them is set as one input of a comparator 4 through a dividing circuit 3 and compared with the signal S1 to be binarized. Further, a pattern detection part 5 detecting the presence of a copper foil pattern from the signal S1 is provided. Only when the output of the detection part 5 judged 'pattern presence', the max. and min. values are sampled and, when judged' pattern absence', the max. and min. values at that time are held and, next, binarization is performed on the basis of a definite threshold value until a pattern is obtained. By this method, even when the frequency of appearance of the copper foil pattern is low, the threshold value is stable and accurate binarization can be performed.
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