Image forming apparatus

摘要

An image forming apparatus of this invention determines a correction amount for each image signal so as to correct banding as periodic density unevenness in a sub scanning direction, corrects each pixel value of an n-bit image signal in accordance with the correction amount, generates the first corrected image signal, and quantizes, for each pixel, the first corrected image signal into a second corrected image signal of m bits smaller than n bits. This image forming apparatus diffuses, in a main scanning direction, quantization errors at the time of quantization of the first corrected image signal into the second corrected image signal so as to cancel the quantization errors within a predetermined region including a plurality of continuous pixels on a main scanning line.

主权项

1. An image forming apparatus comprising:
a correction amount determination unit which determines a correction amount for an image signal so as to correct banding as periodic density unevenness in a sub-scanning direction; an image correction unit which corrects each pixel value of an n-bit image signal in accordance with the correction amount determined by said correction amount determination unit and outputs the image signal as a first corrected image signal; and a quantization unit which quantizes, for each pixel, the first corrected image signal corrected by said image correction unit into a second corrected image signal of m bits smaller than n bits, wherein said quantization unit diffuses, in a main scanning direction which is a direction perpendicular to a correcting direction of the banding, quantization errors at the time of quantization of the first corrected image signal into the second corrected image signal so as to cancel the quantization errors within a predetermined region including a plurality of continuous pixels on a main scanning line.