1. An image processing apparatus for carrying out a process of adding the specific image data of a specific image to the 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 showing the detail information of 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 to said obtained image data on the basis of the image data of the generated two-dimensional code and the pattern image data.