A display system having a number of individual display devices that cooperate to display a large-scale image includes a number of display devices configured to cooperate to produce the large-scale image by each displaying a portion of the large-scale image; at least one camera for imaging the large-scale image displayed by the display devices and an image server receiving output from the camera. The image server is configured to determine whether any mullions exist in the large-scale image using the output from the camera and to modify image signals for the display devices to eliminate any mullions. A method of displaying a large-scale image includes imaging the large-scale image as produced on a display system comprising a plurality of individual display devices that cooperate to display the large-scale image by each displaying a portion of the large-scale image; determine whether any mullions exist in the large-scale image using the imaging of the large-scale image; and modifying image signals for the display devices to eliminate any detected mullions.