1. An image processing apparatus for carrying out a process of adding specific image data of a specific image to obtained image data, comprising: a receiving section for receiving first data and second data concerning the security of the obtained image data; a code generation section for generating image data for a two-dimensional code having a number of cells on the basis of said first data; an encryption section for encrypting said second data and details data identifying said specific image; a pattern generation section for generating pattern image data showing a gradation pattern in a cell of said two-dimensional code on the basis of the encrypted second data and details data; and an addition section for adding additional image data of an additional image based on the generated image data of the two-dimensional code and the pattern image data, and the specific image data to said obtained image data.