| 摘要 |
PURPOSE:To binarize a high quality picture by providing a reference reflecting plate which scans prior to scanning an original, a memory tracking the background of each picture element in a main scan direction and a means tracking the background. CONSTITUTION:Prior to reading the original 1, a lamp 4 reading a scanner part, mirrors 6, 7 and 8, a projecting lens 9, a CCD sensor 10 scan the reference reflecting plate 5, and set the initial value of the background at every picture element. In terms of original scanning, only when the number of picture elements necessary for updating the contents in the memory used for tracking the background at every picture element in the main scan direction exceeds the regulated value, the background of all picture elements on one scan line is tracked according to a predetermined function, and the background is corrected. Afterwards, it is binarized. Even if the omission of the background due to a file punching hole, a reinforcing punch, a notch, etc., is present, the background tracking is not disturbed, whereby a high quality binarization picture can be obtained.
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