Image processing apparatus

An image processing apparatus comprising:

• a) first correction means for correcting an error of a multilevel image data input by an input unit from a document, so as to supply first corrected data having a specified number of bits;
• b) multilevel rendition means for performing the functions of:
• 1) generating (i) multilevel rendition data and (ii) first error data, by comparing the first corrected data with a plurality of predetermined threshold levels;
• and
• 2) supplying corrected multilevel image data to an output unit, wherein the corrected multilevel image data allows the output unit to output an output image in which multilevel image data is assigned to each pixel of the output image;
• and
• c) error diffusion means for performing the functions of:
• 1) carrying out a prescribed error diffusion of the first error data;
• and
• 2) supplying second error data to the first correction means for use in an error correction process applied to subsequent input image data;
• wherein the diffusion means includes
• 1) level selection means for selecting a number of bits for the second error data, so as to allow the multilevel rendition means to correct the multilevel rendition data using first corrected data which has been corrected using the selected number of bits of the second error data.