| 摘要 |
PURPOSE:To improve the general utility of video signal and to simplify an analog circuit structure by providing the comparator outputting binary image signal of an object when a comparison is made between a low pass filter and a D/S converter which offsets the output of the low pass filter and other comparison is made between video signals and output signals of its low pass filter. CONSTITUTION:A CPU 3 selects a soft setting signal corresponding to the flat areas of a work W which is nearmost to a reference area. Also it is outputted into a D/A converter 4 to convert to an analog quantity A and is added to the output F of the low pass filter 2. Because of a fact that output signal S, being as a floating threshold, is compared sizewise with a video signal V by a comparator 5, the video signal V is converted to a binary image signal T. Thus the offset quantity of the floating threshold is adequately set by the D/A converter 4 and the necessity to perform fine-adjustments of the gain of its low pass filter 2 and also the need for altering the gain at every change of image objects W to be detected are eliminated. In addition, as there is the only low pass filter 2 as the analog circuit, the constitution of the analog circuit is simplified.
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