| 摘要 |
PURPOSE:To emphasize a picture signal, and to prevent an error from occurring with a simple circuit, by setting the picture signal to a white signal in the case of generating an overflow compulsorily, and setting it to a black signal in the case of generating an underflow compulsorily. CONSTITUTION:An overflow/underflow detection circuit 61 is a circuit which detects an overflow or an underflow with the most significant bit of a difference data from a subtractor 55, and an overflow signal from an adder 58, and outputs the overflow signal, or an underflow signal, as a detected result, and is constituted with inverter circuits 64 and 65, an OR circuit 66, and a NOR circuit 67. A compulsory black and white circuit 63, when neither the overflow signal nor the underflow signal is supplied, outputs a signal from a binarization circuit 60 as a white signal '1', or a black signal '0', and when the overflow signal is supplied, it outputs the white signal '1' compulsorily regardless of the signal from the binarization circuit 60, and when the underflow signal is supplied, it outputs the black signal '0' compulsorily regardless of the signal from the binarization circuit 60.
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