| 摘要 |
PURPOSE: To perform an appropriate AE processing regardless of the kind of an original by correcting the base level of formation pictures based on a density histogram for monochromatic pixels among the three-color picture data of the original. CONSTITUTION: Picture data read by a CCD are passed through A/D conversion, shading correction and inter-line correction and turned to red, green and blue picture data R, G and B37-30 . A histogram generation part 602 judges the pixel for which a level difference among the respective colors is smaller than a reference value as the monochromatic pixel for the RGB picture data R, G and B37-30 appropriately interpolated among the entire pixels. When the ratio of the monochromatic pixels occupying an entire screen is less than a prescribed threshold value, a color original is judged and the levels of the respective colors are corrected so as to let a base be white. At the time of judging a monochromatic original, the gradation histograms of the respective colors are generated only for the monochromatic pixels further and the levels of the respective colors are corrected so as to attain the optimum base. |
