Patent ID: 7554697

Claim:
An image forming apparatus, for forming an image with using distributions of two or more types of dots having different densities per unit area in a same hue, comprising: a threshold value matrix having a size of a prescribed region smaller than an input image; and a dot formation determining section for carrying out comparison between a pixel value at a target pixel in the input image and a threshold value allocated at a position corresponding to the target pixel in the threshold value matrix, and for determining, based on a result of the comparison, whether to form or not to form any one of the two or more types of dots having different densities per unit area at the position corresponding to the target pixel, wherein, the dot formation determining section comprises: a first dot formation determining section for comparing the pixel value with the threshold value allocated at a position corresponding to the target pixel, and determining whether to form a first type of dot among the two or more types of dots; and a second dot formation determining section for determining whether or not to form a second type of dot among the two or more types of dots at a position where the first dot formation determining section has determined not to form the first type of dot, wherein, threshold values in the threshold value matrix are configured so that a frequency of dot formation is lower, for gradation regions in which a dot density of any of the two or more types of dots having different densities is low and/or high, than a frequency of dot formation for gradation regions in which the dot density is in average level.