| 摘要 |
PROBLEM TO BE SOLVED: To improve image quality in reading a color image at a monochrome image reading speed by using a four-line CCD sensor. SOLUTION: A color image signal read at a monochrome image reading speed is averaged by an averaging circuit 530 of a color signal correcting circuit 335 such that an S/N of the color image signal is improved. In a CrCb calculation circuit 540 and an RGB resolution correction circuit 550, the resolution of the color image signal is improved using a monochrome signal K as a luminance signal Y of the color image signal. A color photo-diode array (RGB) and a monochrome photo-diode array (K) of an image sensor unit 310 are shifted by 1/2 pixel in a main scanning direction, and centerlines of the color image signal and the monochrome image signal after averaging processing are matched, thereby eliminating color shift between the color image and the monochrome image. COPYRIGHT: (C)2007,JPO&INPIT
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