JPS55166377A - Reading device for double-color original - Google Patents

Abstract

PURPOSE:To eliminate the error of the color decision appearing to the reproduced color, by performing the arithmetic process through the delay of the analog signal obtained with the photoelectric conversion after the value multiplication given. CONSTITUTION:Analog color signals 9 and 10 of red and bluish green each sent from photoelectric converter 1 are turned into multiple value in 8 steps through value multiplying circuit 26, and red signal 20 is supplied to delay circuit 27 to receive the delay of 7 hours until next value-multiplied signal 21 is obtained. Signals 20 and 21 are supplied to arithmetic process circuit 28 at one time to obtain difference signal 22. And in case the original is white in color, signals 20 and 21 show a high logic level each. These logic levels are low and intermediate when the original is black and gray respectively. Thus red color decision signal 23 is obtained with logic level 1 referred to as the red color by binary-coding signal 22 through binary-coding circuit 29a and with a proper threshold level. For signal 20, black color decision signal 24 is obtained in the same way through binary-coding circuit 29b in case the original is black. In such constitution, the error of the color decision or the distortion of the signal waveform can be eliminated.