An image processing apparatus determines an embedding method for embedding sub information into a main image to be printed on a recording layer based on the degree of optical shielding of a protection layer or a security layer formed on the surface of the recording layer, on which an image is to be printed, with respect to the surface of the recording layer in a recording medium, and generates a composite image obtained by embedding the sub information into the main image by the determined embedding method as the image to be printed on the recording layer of the recording medium.