| 摘要 |
PROBLEM TO BE SOLVED: To permit satisfactory range correcting processing without requiring prescan by reading an original image while dividing it into plural lines, determining the correction reference value of the original image by calculating the correction reference value for the unit of a line based on these image data for the unit of a line, and performing density range correcting processing to the image data for the unit of a line corresponding to the original image. SOLUTION: The shading corrected image data for one line of an original stored in a line memory are successively provided to a multilevel page memory control part 97. Based on the shading corrected image data, a histogram preparing part 201 prepares a density histogram for one line of the original and successively provides the result to a reference value calculating part 202. The reference value calculating part 202 calculates a temporary white reference value R10 and a temporary black reference value R20 for one line of the original in real time and supplies them to a reference value determining part 203. The reference value determining part 203 provides determined white reference value R11 and black reference value R21 to a range correcting part 204 and performs the range correcting processing to the image data. |
