According to the present invention there is provided a projection device, which is configured to project an image which is co-operable with images projected by one or more other projection devices, wherein the projection device comprises a detector operable to detect characteristics of images projected on a display surface by the projection device and one or more other projection devices, and a controller operable to adjust the projection device and/or to adjust one or more of the other projection devices, based on the characteristics of the images detected by the detector, such that the images projected by each projection device co-operate on the display surfaces.