Patent ID: 7474443
Filing Date: 2009-01-06
Classification: H04N

Abstract:
1. An image forming apparatus, for forming an image with using two or more types of dots having different densities per unit area in a same hue, comprising: a first dot formation determining section, for making comparison between a pixel value of a target pixel in the input image data and a first threshold value allocated at a position corresponding to the target pixel in a prescribed threshold value matrix, and for determining, based on a result of the comparison, whether or not a first type of dot, out of two or more types of dots having the different densities per unit area, should be formed at a position corresponding to the target pixel in an image to be formed; a first calculating section for calculating a corrected threshold value matrix by correcting the prescribed threshold value matrix; a second calculating section for calculating a second determining condition by reflecting the corrected threshold value matrix, to determine whether or not a second type of dot out of the two or more types of dots should be formed; and a second dot formation determining section for determining whether or not the second type of dot should be formed, based on a value obtained by assigning an error to the pixel value of the target pixel with an error diffusion process and the second determining condition, at the position where the first dot formation section has determined not to form the first type of dot.