PURPOSE:To generate a compressing signal for the first white picture of one line with simple constitution by providing a circuit for replacing a black picture element into a white picture element when the head of inputted picture data is a black picture element. CONSTITUTION:A binary picture signal VIDEO is inputted to an FF222 and after a video enable signal VEN rises, a change signal of the picture signal VIDEO is inputted to a negative logic OR gate 217 from an exclusive OR gate 225. Run length counters 211-213 count a clock signal CLK, and when an output is obtained from the gate 217, the count value at that time is transited to registers 232-234 and the value is transmitted to a compression code generating circuit 236 together with a kind signal of a picture element in the register 231. Then the compression code is generated. The register 231 outputs a white picture element signal by one clock only even when the first line is a black picture element.
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