| 摘要 |
PURPOSE:To obtain a binary-coding signal where the variation of the sensitivity of a photoelectric transducing cell and the lighting of an original are corrected by generating a threshold data from the combination between a dark reference data and a light reference data so as to store the result in a RAM. CONSTITUTION:A dark original with less glitter is read from an image sensor at first and given to the 1st address input of a ROM 4 via an A/D converter 2 and a latch circuit 3. The data are writen in a RAM 5. Then white paper with high reflectance is read by the image sensor and given to the 1st address input A1 of the ROM 4 similarly as the light reference data. The dark reference data stored in the RAM 5 is given to the 2nd address input A2 of the ROM 4, resulting that the threshold data corresponding to the combination of the dark reference data and the light reference data is outputted from the ROM 4 and written in the RAM 5. The picture data read are subjected to binary coding processing based on the said threshold data.
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