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, including: a threshold value matrix; 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 corresponding to the target pixel in the threshold value matrix, and for determining, whether to form or not to form any one of the two or more types of dots, 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 is low and/or high, than that for gradation regions in which the dot density is in average level.