| 摘要 |
PURPOSE:To prevent a variation in density and a change in image quality from occurring by a method wherein a gradation is normalized using printer characteristics and a maximum image, density, obtained from a test pattern made visible after developing properties are fixed, as the reference. CONSTITUTION:A data operation part D generates a signal by logarithmically converting a ratio of a rated maximum output (an output in the absence of a toner on an image holding body) of a patch detection sensor C to an output voltage normalized to 256 gradation by A/D converting a luminance signal by taking a difference between a density of the image holding body and a density of transfer paper into consideration. For removing a detection error caused by a vibration produced during rotation of an image holding body B, a luminance signal obtained from a plurality of gray scales made visible, for example, on the image holding body B is subjected to the aforesaid processing to be averaged, and a signal of the averaged value is transmitted to an image processing part E and a process CPU 90. In this manner, the image processing part E and the process CPU 90 can detect printer characteristics and a maximum image density without a detection error. |
