| 摘要 |
PURPOSE:To improve the data compression efficiency by irradiating light to the next read point with a set value corresponding to the quantity of emitted light for black discrimination if the preceding read point is discriminated as black and irradiating it with a set value set correspondingly to the quantity of emitted light larger than said set value if the preceding read point is discriminated as white. CONSTITUTION:Read points on a form M1 on which a picture is recorded are illuminated with the quantity of emitted light corresponding to a set value by a light emitting means M2. The intensity of the reflected light is detected by a detecting means M3 and is inputted to a discriminating means M4 and is compared with a prescribed value set preliminating as a black/white discrimination reference of the read point. The discrimination result and the number of the same continuous discrimination results are stored in a storage means M5. If the read point read by the means 4 just before is discriminated as black, a setting means M6 sets the first set value which is set correspondingly to the quantity of emitted light for black discrimination when the next read point is irradiated by the means M2; but if the read point read just before is discriminated as white, the means M6 sets the second set value set correspondingly to the quantity of emitted light larger than the first set value. Thus, the data compression efficiency is improved.
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