1. A printing device for forming dots in pixels arranged on a printing medium according to an input image data and printing an image to perform printing of an output printed image, the printing device comprising: a printing unit configured to print the output printed image by dividing formation of the dots in a common region into a plurality of pixel groups, in a case where first and second pixels belonging, respectively, to two pixel groups among the plurality of pixel groups are proximal pixels in a predetermined gradation range in which probabilities k1 and k2 at which a dot is formed in the first and second pixels are such that k1<0.5 and k2<0.5, a probability K of a dot being formed on both of the proximal pixels is set to be close to k1·k2.