| 摘要 |
PURPOSE:To convert a color picture signal into a black and white picture information of well-balanced density by decreasing the color picture signal to accomplish the said convertion. CONSTITUTION:In an electronic file 101, four colors of Y (yellow), M (mazenda), C (cyan), and Bk (black) for purpose of subtractive mixing are stored. The Bk signal 103-1 is supplied to an OR gate 110 without being decreased. Respective picture elements of Y-signal 103-2, of M-signal 103-3, and of C-signal 103-4 are respectively thined in order to provide a density balance i.e. to make proper proportions to the black. The period of decreasing is set by selecting a prime number in order to prevent a bit-missing in the direction of subscanning or moire pattern from occurring due to the repeated decreasing. The decreased signals of Y, M and C (the output from And gates 107, 108, and 109) are synthesized by the OR gate 110 to drive the driver 111 of a laser diode.
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