An image processing apparatus performs a density adjustment process for generating an image containing a copy-forgery-inhibited pattern image for warning against the use of copy products. To help users to easily adjust the density of a latent image portion and a background portion in the copy-forgery-inhibited pattern image, the image processing apparatus determines a density relationship of the latent image portion and the background portion by performing a plurality of adjustment operations, in combination, different in the amount of adjustment relating to the range of variable density in at least one of the latent image portion and the background portion, and sets, based on the density relationship, the density data of each of the latent image portion and the background portion in the data of the copy-forgery-inhibited pattern image.