As a result of the processing by the dot arrangement unit, dots are arranged so that in a first edge pixel group located in a first end portion of the object in the scanning direction and adjacent to a boundary between the object and an outside of the object, a ratio of arranging dots in the second regions is lower than a ratio of arranging dots in the first regions, and in a second edge pixel group adjacent to the boundary and located in a second end portion different from the first end portion and on a opposite side of the first end portion in the scanning direction, a ratio of arranging dots in the first regions is lower than a ratio of arranging dots in the second regions.