| 摘要 |
PURPOSE:To execute the smoothing of density without losing the necessary sharpness of a gradation characteristic picture by providing a means to generate a pseudo half tone dither pattern. CONSTITUTION:A subtracter 2 subtracts picture data at the present time point from the just before picture data held at a latch 1 and sends the result to a gate 3. The gate 3 detects whether or not the absolute value of the subtracting result is 1 and when a control signal E is 1, the gate outputs the result. At such a time, an adder/subtracter 4, by a sign signal S, decreases 1 from picture data GD when the output of the subtracter 2 is -1 and increases 1 when the output is +1. Input picture data GD to the adder subtracter 4 shifts and inputs digits to the higher order of one bit and therefore, finally when the difference between the just before picture data and the picture data at the present time point is + or -1, the circuit is operated so that the pseudo half tone dither pattern can be generated.
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