An image transmission apparatus includes a display device, a display image data generator, a storage device, a storage controller, a transmitter, and a display controller. The image transmission apparatus is connectable to a plurality of image projection apparatuses. The display image data generator is configured to generate display image data, the storage device is configured to store the display image data, and the transmitter is configured to transmit the display image data for display on each image transmission apparatus connected to the image transmission apparatus according to an overall layout display for the combination of potentially connected image transmission apparatuses. The display controller is configured to display an image on the display device using the display image data and to display a plurality of layout display images corresponding to the display image data transmitted to the image projection apparatuses in a layout display region on the display device.