1. An image processing apparatus for generating image data having a dot image used to suppress information leakage, comprising: a generation unit configured to combine a first dot image, which is visually recognizable on a copied material and includes a latent image and a background image used to suppress information leakage, with a second dot image, which is embedded with information used to suppress information leakage, and to generate a third dot image including the latent image and the information used to suppress information leakage; and an image data generation unit configured to generate image data having the third dot image by combining the third dot image with predetermined image data, wherein, the generation unit is also configured to convert a region of the latent image and a region of the background image in the first dot image into binary data so as to have different binary data from each other, convert a region of the latent image in the binary data into dot data by expressing the region of the latent image as dots, convert the second dot image into outline data by removing dots of a region corresponding to the region of the latent image to form an outline region, and wherein the dot data is combined with the outline data to generate the third dot image in which the outline data is generated as a latent image and the dot data is generated as a background image.