To enhance the operating efficiency of an image forming device by preventing excess toner consumption, earlier wear of a photoreceptor, and load increase in a cleaner or the like while maintaining prescribed image quality so as to reduce the time for image correction processing.
A density of a gradation test pattern formed by a simple medium tone process control with a small forming number of pattern images is measured (101, 102), and approximated data are obtained by applying approximation processing to detected data (103). A rate of change at preceding correction is compared with a rate of change at this correction (104), a detailed medium tone process control with many forming numbers of pattern images is shifted only when a difference is 0.1 or over (105). The detailed medium tone process control is selectively performed on the basis of a gradient of an approximated straight line obtained by the simple medium tone process control and the detailed medium tone process control is not conducted under a state where a sufficiently accurate gradation correction curve can be obtained by the simple medium tone process control.
OTA TOSHIHIRO
IMAGAWA SHINJI
INO TOSHIAKI
KITAGAWA TAKASHI
MAEDA YASUTAKA
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