| 摘要 |
PURPOSE:To make color discrimination of two colors by simple circuit configuration by making the threshold level that binary codes specific color component larger than threshold level of a complementary color system by a fixed amount. CONSTITUTION:An A/D convertor 9 digitizes a red color signal outputted from a photoelectric transducer 6 and an A/D convertor 10 digitizes a blue green color signal which is complementary color of red color outputted from a photoe lectric transducer 8. Comparators 13 and 14 compares these red color and blue green color signals with threshold levels Vref1, Vref2 and binary codes them, and outputs a monochrome detection signal S7 and a red detection signal S9 respectively. In above-mentioned comparators 13,14, the threshold level Vref1 of red color system is made larger than that of blue green system by a fixed amount. Accordingly, even when deviation occurs between above-mentioned red and blue green signal levels in reading a gray colored original, discrimina tion of white or black can be surely made.
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