| 摘要 |
PURPOSE:To detect an original size without working a platen cover by detecting the position of the shadow of an original side edge in a main scanning direction and a subscanning direction which is generated on the platen cover when the original is illuminated, CONSTITUTION:The original G is placed on an original platen and scanned, and as to the image signal of a line (1) which is obtained as the result, the image signal obtained every picture element section H1, H2...Hn is integrated in the subscanning direction with reference to all the scanning lines. The picture element sections H1 to Hn are set by dividing the width A of the original platen at equal intervals. Next, the integrated value obtained every picture element section is differentiated, then, the length L of the original G is obtained based on the position of a change point where the obtained rate of change exceeds a threshold at first from the final scanning line position, that is, the position of the shadow of the trailing end of the original. On the other hand, the piece number (k) of the positions of the shadow included within a central value Lc + or -an error value DELTAL is inspected among (n) pieces of picture element sections H1 to Hn, and the width W of the original G is calculated by multiplying the piece number (k) by a pitch (w) of the picture element section. |
