When image blending, we overlap projectors to create what is referred to as an overlap region. The answer lies with the use of image blending. This results in a tiled appearance, rather than a seamless one as shown in Figure 2. Some areas will overlap whilst others will have a gap. Secondly, it is a difficult task to manually adjust a projector to exactly the right position so that they match up at the edges. For example, an image may drift as they warm up and the brightness and colors will also differ slightly even if the same projector brand and model are used.
Firstly, different projectors have different characteristics, even if you are using the same brand and model. In principle it sounds easy, but in practice it is very hard to do. Unfortunately, achieving a seamless image using this technique is near impossible. To try and accomplish this, the projectors are carefully arranged so that the right-hand edge of the left-hand projector sits perfectly next to the left-hand edge of the right-hand projector. This method is technically referred to as image butting because the projected images are butted up next to one another.
Figure 1: A wide image that we want to project using three projectors.Īt first glance it might appear that the easiest way to produce this image across three projectors would be to line up the projectors next to each other. In both cases, a number of projectors are needed which are firstly overlapped and then visually joined together using an edge blending technique. Typically, this is done to increase the size of a projected image to make a very wide image, or by combining a number of lower resolution devices together to increase the total resolution of a display. In order to blend it together, you need to reduce the brightness in addition to matching the image.Edge blending is a technique used to describe the process of visually combining several projected images to make a single seamless image. If you have two images side by side and the middle 20% is doubled, obviously that portion is going to be brighter than the rest of your image. The second part of the process involves feathering the images to eliminate the “hot spot” that is guaranteed to occur. This overlapping gives you a larger area to match up which eliminates the hard edge you’d see if you simply placed the two images side by side. Essentially you send the same portion of your image across two projectors. The first is basically just overlapping two images. So, how does edge blending really work? There’s basically two processes.
Essentially, this is what edge blending will accomplish. Much like when you paint a wall, you always overlap your strokes to get as even a coverage as possible. When you place two projectors side by side, the human eye will notice the edge, the mismatched colors, and the split or overlap of the images. Simply put, when you have two projectors lined up next to each other creating one solid image, you will never be able to create a seamless edge without edge blending. We have used all three with varying results. There are numerous ways to handle edge blending including software, hardware, and physical applications. We’ve touched on the concept of edge blending before, but have never dived too deeply into the subject matter.Īt it’s basic form, edge blending occurs when you combine (overlap) the edges of two projectors in a multiscreen setup.