A condition on the attribute of an image for generating multi-frame image data containing a plurality of frames of images per file from image data is stored beforehand. When image data is received, multi-frame image data is generated from the received image data based on incidental information contained in the image data and the condition stored beforehand. Then, the generated multi-frame image data is archived. When a request for an image is made by a certain terminal, an application functioning on the terminal is identified, and multi-frame image data appropriate for the application is sent from among the generated multi-frame image data.