Patent attributes
A scanner with an automatic density adjustment function executes image processing in which prescanning is performed and the background level is made white before the next scan starts. However, if an automatic density adjustment is applied when the same document is read as a color image and as a monochrome image, it is necessary to perform prescanning before the color image is read and prescanning before the monochrome image is read. Reading the image therefore takes time. Accordingly, if an automatic density adjustment based upon prescanning has been designated, prescanning is carried out and then a histogram is obtained for each of the components R, G and B and the background levels are calculated for color scanning and monochrome scanning. A table in a scanner image processor is set in accordance with a background peak value PeakBW for monochrome scanning. For color scanning, on the other hand, the table in the scanner image processor is set in accordance with a background peak value PeakCL for the color scan.
