| 摘要 |
PROBLEM TO BE SOLVED: To provide an image data reader in which its arithmetic circuit can be made small-sized, which accelerate its operation speed and whose cost can be lowered. SOLUTION: Multi-gradation luminance value data of a picked-up image are read out of a frame memory 302, a 1st timing circuit 401 generates a luminance value which is a read cycle behind now, and a subtracting circuit 402 generates a luminance variation quantity; and a 2nd timing circuit 403 generates luminance value variation quantities of three cycles matching the read cycle, a border reference point and correction point setting circuit 404 generates a maximum and a minimum point from those variation quantities and regards the detected points as border reference points and a point which is larger in absolute points between two adjacent point as a border correction point, a correcting circuit 405 derives a correction quantity for a black-and-white border from the luminance value variation quantities of the reference points and correction point, and a border pulse generating circuit 406 converts the correction quantity into time amount to generate border pulses, thereby a black- and-white border is set. |
