| 摘要 |
PROBLEM TO BE SOLVED: To adjust a dynamic range of a read image by a method that enables elimination of noise and dispersion in components attending a conventional analog processing and cost cut with a simple circuit. SOLUTION: A gain arithmetic section 39 multiplies a gain coefficient by input image data from a digital processing stage, that is, an analog/digital converter 34 to adjust output data to have an object output level (adjustment of dynamic range). A gain calculation section 38 obtains the gain coefficient from a level detection value by white/background level detection sections 36, 37 of a reference section (reference white board/background of original) and the object output level. A different gain coefficient is calculated in correspondence with a reading of the reference white board/original in a background elimination non-background elimination mode or a non-background elimination mode. In the case of a plurality of pixel (even number/odd number) systems, the processing of other pixels is simplified by a ratio to the reference pixel.
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