A printed material is read to provide an image data thereof. The printed material includes an image of an original, and an additional image not recognized or hard to be recognized with naked eyes. The additional image is to be visualized when an image is formed based on the image data with an image forming apparatus. Further, the printed material includes and a code which represents information. When the code is detected in the image data, a stamp image is synthesized with the image data based on the detected code. Then, the image data synthesized with the stamp image is provided. For example, an image is printed based on the image data.