An image processing system readily provides a client PC with preview of a target image for printing or transmission. In accordance with a request from a client PC (information transmission direction i), a server 2 requests a MFP 1 to generate base image data by reducing the size of an original image and to transmit information of image editing contents available for the MFP 1 to the server 2 (information transmission direction ii). In accordance with the requests from the server 2, the MFP 1 subsequently provides the base image data and necessary information to the server 2 (information transmission direction iii). Then, the server 2 provides the client PC with a preview window to display the image data obtained by reducing the size of the base image data and an image editing window to display image editing contents available for the MFP 1 (information transmission direction iv).