A digital signage system comprising: a first display device ; a second display device arranged to be at a first spatial distance (d1) from the first display device and having a display screen that at least partially overlaps a display screen on the first display device ; a third display device arranged to be at a second spatial distance (d2) from the second display device and having a display screen that at least partially overlaps the display screen on the second display device , and a controller configured to: control the first display device to display single image data during a first time interval (ti1), and control the second display device to display the single image data during a second time interval (ti2) based on the first spatial interval (d1) between the first display device and the second display device , control the third display device to display the single image data during a third time interval (ti3) based on the second spatial interval (d2) between the second display device and the third display device ; differently control a brightness of the first display device , the second display device , and the third display device , via lamp units , wherein each of the first display device , the second display device and the third display device include a lamp unit ; control the brightness of the display device (610, 710, 810, 910; 620, 720, 820, 920; 730, 830) that is currently displaying the single image to be brighter than the brightness of the other display devices (610, 710, 810, 910; 620, 720, 820, 920; 730, 830) that are currently not displaying the single image, wherein at least one of the first display device , the second display device , and the third display device is a transparent display . a first display device ; a second display device arranged to be at a first spatial distance (d1) from the first display device and having a display screen that at least partially overlaps a display screen on the first display device ; a third display device arranged to be at a second spatial distance (d2) from the second display device and having a display screen that at least partially overlaps the display screen on the second display device , and a controller configured to: control the first display device to display single image data during a first time interval (ti1), and control the second display device to display the single image data during a second time interval (ti2) based on the first spatial interval (d1) between the first display device and the second display device , control the first display device to display single image data during a first time interval (ti1), and control the second display device to display the single image data during a second time interval (ti2) based on the first spatial interval (d1) between the first display device and the second display device , control the third display device to display the single image data during a third time interval (ti3) based on the second spatial interval (d2) between the second display device and the third display device ; differently control a brightness of the first display device , the second display device , and the third display device , via lamp units , wherein each of the first display device , the second display device and the third display device include a lamp unit ; control the brightness of the display device (610, 710, 810, 910; 620, 720, 820, 920; 730, 830) that is currently displaying the single image to be brighter than the brightness of the other display devices (610, 710, 810, 910; 620, 720, 820, 920; 730, 830) that are currently not displaying the single image, wherein at least one of the first display device , the second display device , and the third display device is a transparent display . <EOS>