While edge blending is not a new practice, it has regained attention due to the rapidly growing demand for immersive exhibitions. This technique is particularly sensitive in applications involving dark contents.

In an edge blending setup, a specific challenge arises: the overlapped section of the image appears unnaturally brighter than other regions, especially when projecting dark scenes in a dark environment. This issue occurs because projectors emit a faint amount of light onto the screen, even when projecting a black image. When two or more projected images overlap, the overlaid light leads to an uneven black level across the entire screen, resulting in a “banding effect” in the overlap area. We consider this to be a consequence of the inherent limitations of projector technology. In general, the higher the native contrast ratio* of the projectors, the lower the light leakage and the less obvious the banding effect when showing dark scenes.

*Note: Native contrast ratio is the ratio of white and black measurements from the same image at the same time. This is considered relatively true contrast ratio comparing to Dynamic contrast ratio or so called “full-on full-off contrast ratio”.