| 摘要 |
PURPOSE:To measure seal line width and white area without being affected by the density variation of the ink of a seal nor variation of lighting by varying a slice level according to variation in the area of the seal part and variation in the ground signal level of the seal. CONSTITUTION:A video signal inputted from an input terminal 1 is inputted to a DC detector 5 to extract the signal level of the seal ground and a DC component and an integrator 7 extracts the area signal of a section determined by a synchronizing circuit 11. The slice level outputted by a latch circuit 10 is inputted to a comparator 3 and the original video signal is converted into a binary signal. Therefore, the slice level inputted to the comparator 3 id determined by the variation rate of the area signal within the range determined by the synchronizing circuit 11 and the variation rate of the signal level of the seal ground.
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