1. An image forming apparatus comprising: a unit configured to generate a normalized tile image from a tile image, wherein the normalized tile image is a unit of a pixel pattern representing a characteristic of the tile image; a unit configured to calculate the number of the normalized tile images that can be arranged in a drawing region after variable magnification of the tile image with a predetermined variable magnification rate; a unit configured to generate a tile image in which the calculated number of the normalized tile images are arranged in the drawing region after the variable magnification, as the tile image after the variable magnification, if the calculated number is greater than or equal to a first threshold value; and wherein the unit configured to generate a tile image as the tile image after the variable magnification generates, as the tile image after the variable magnification, an image obtained by variably magnifying the normalized tile image so that the size of the normalized tile image becomes the same as that of the drawing region after the variable magnification, if the calculated number is less than the first threshold value.