Patent ID: 6956673

Claim:
An image processing apparatus converting first image data having a predetermined number of gray levels into second image data having a smaller number of gray levels than said predetermined number comprising: an input unit successively inputting a signal of each pixel in the first image data; an occurrence probability setting unit setting per pixel an occurrence probability of each gray level of the second image data according to said input signal; a threshold setting unit setting per pixel a threshold used for converting the input signal of each pixel of the first image data into a signal of each pixel of the second image data; a converting unit according to said set occurrence probability and said set threshold to convert said input signal of each pixel of the first image data into the signal of each pixel of the second image data; a calculating unit according to a gray level of said signal of each pixel of the second image data generated by the conversion and to said set occurrence probability or said set threshold to calculate a feedback value for an adjacent unprocessed pixel; and a correcting unit according to said calculated feedback value to correct the occurrence probability or threshold used for converting the unprocessed pixel.