| 摘要 |
PURPOSE:To prevent deterioration of the gradation representability, which is caused by variable density of an original, by detecting a variable density level of the original by other detection element at the same time when the original is scanned by the solid scanning element, and setting a threshold level of dither matrix. CONSTITUTION:An original 1 is scanned by the solid scanning element 4, and a gradation signal is output by the dither matrix. At the same time when said scanning is executed, variable density of the original is detected by the photodetector 5 which has been installed in front of the solid scanning element 4 in the subscanning direction D2. This detection output S is made a reference level of the dither. In this way, a threshold level of the dither matrix is set in accordance with variable density of the original, and the gradation representability is not deteriorated even when variable density of an original has been changed. |
