| 摘要 |
PURPOSE:To attain the distinction between two colors with simple circuit constitution by generating a density signal of an original image and a color signal representing whether or not the color is a specific color and applying logical operation to the signals by means of a logic circuit. CONSTITUTION:Red and blue/green signals S1, S2 outputted from photoelectric conversion elements 6, 8 are digitized, then the result is inputted to sum/ subtraction computing elements 13,14. The sum computing element 13 and a comaprator 15 generate a density signal S9 of an original image and the subtraction computing element 14 and a comaprator 16 output a color signal S10 representing whether or not the original image is red. A discrimination circuit comprising inverters 17,18 and AND circutis 19,20 outputs a red detection signal S11 when the density signal S9 represents ''deep'' and a color signal S10 represents a red signal and outputs a black detection signal S12 when the density S9 represents 'deep' and the color signal S10 is other than a red signal. Further, the circuit discriminates a signal as 'white' independently of the color signal S10 when the density signal S9 is 'light'.
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