1. An image forming apparatus, comprising: a noise adding unit configured to add a noise pattern to a print image; and a controller configured to perform printing of the print image in which the noise pattern has been added; wherein the noise pattern is a pattern obtained by two-dimensionally arranging plural noises of which each has a local planar distribution; and each of the plural noises has a local planar distribution in which pixel values monotonically vary with a distance from a pixel having a peak pixel value.