An information processing system includes an information processor for transmitting image data to an image processor together with device information, and plural image processors for performing, according to the device information, processes to the transmitted image data. The information processor comprises a setter to set the device information and command information, and a transmitter to transmit data including the device and command information to the image processor. The image processor comprises a device information memory, a device information setter to set the device information to the memory, and a selector to, according to the transmitted device information, set the device information according to the command information to the memory, change the command information, and select whether to transmit the data including the changed command information to the next image processor or transmit the transmitted data to the next image processor as it is.