Edge Blending With Projectors

For some applications, a single projector just may not cut it. It’s axiomatic that people prefer larger, more dramatically shaped images. Going strongly horizontal or vertical is a simple way to execute an impactful look, but it does take a little fine tuning to get it right. Fortunately, modern projectors are designed to facilitate edge blending modes, so a little fine tuning is all it takes. And edge blending is typically only needed when the image is displayed on a surface that can be best described as environmentally neutral. In most cases, edge blending isn’t necessary when putting together environmental projection imagery. Still, edge blending is a valuable feature to look for in a projector, and a valuable skill to nail down.

Why bother with edge blending?

The question remains, why even fiddle with edge blending to begin with? Can’t the projectors just be arranged so that their projected images are right next to each other? Both of those questions are easy to answer and suggest why edge blending is particularly useful. Consider some of the applications that edge blending can be deployed for, including:

1. Education – Projectors are a mainstay at universities, and have gained some traction among K-12 schools as well. In a standard size classroom, edge blending may not be desirable, but in a large lecture hall or auditorium, it can be taken full advantage of. There is plenty of room in a lecture hall to fit two or more projectors, and that takes care of the only significant impediment to edge blending.

Because edge blending extends image boundaries, educators can use this extra space for additional lecture notes or for media. As students often have difficulty remaining engaged when sitting far away from a lecturer, educators can compensate for this by providing supersized presentation material.

2. Business – Engagement is the key word for businesses, especially when it comes to media. Restaurants and shops have to work hard to get consumer attention, and the best way to do this is with compelling visuals. But, of course, people are able to attenuate most forms of advertising and branding. Today’s world of bright, viral, social marketing makes that a necessity.

But most people still respond well to images that don’t fit the standard. Going big and dramatic is one way to avoid boring branding, and edge blending opens up that possibility. Imagine a restaurant greeting its patrons with looming photos of menu items or specials, and keeping those patrons interested while waiting for a table. Imagine a luxury clothing store using projectors to group images of like accessories together. It’s an approach that can be used with any kind of business – jewelry, toys, hardware, sporting goods, electronics or kitchen accessories. The applications are truly endless.

3. Government – For most people, interacting with governmental organizations isn’t an exciting experience. Whether in line at the DMV or at the courthouse, there’s a lot of boring waiting, and usually a lot of information for visitors to digest. Both issues can be dealt with simultaneously, using projectors with edge blending. Larger imagery will get peoples’ attention while waiting in line, and this provides a perfect opportunity for government facilities to relay essential procedures or other useful information. And because this is delivered in a novel way, it will keep people from getting agitated from boredom.

4. Museums and galleries – Outsized images are a natural fit for art galleries and museums. The extra visual real estate means galleries can present some interesting exhibits. Museums need every square inch of space they can get to deliver as much information as possible, but engagement must also be maintained. Edge blending does both, and can be used with any kind of science, history or art exhibit.

There are, in short, plenty of applications for large imagery, but is edge blending really the best way to deliver that imagery? The answer is yes, as long as projectors are the preferred medium.

Edge Blending Beats All

At a glance, edge blending may seem like a waste of effort. Why not just align the projectors so their projected images are right next to each other? The problem with this approach is obvious – it doesn’t work. People are extremely adept at picking out any incongruities in an image. Humans are pattern seeking animals, after all. And this ability to suss out rough spots means those hard edges between the projected images will stick out like a sore thumb. In fact, those hard edges will undermine the entire project, so it’s not as simple as just sticking a few projectors next to each other and wiggling them around until the fit is mostly there. Mostly isn’t good enough, but edge blending takes “mostly there” to “perfect fit.” How does it work? Fortunately, current generation projectors are built with intuitive modes for quick and easy edge blending. The only thing a user needs is more than one projector. The process is slightly different for every projector brand and model, but it usually looks something like this:

1. Turn on the projectors’ test card – Prior to edge blending, users should select a test card that will be used as a reference for image adjustment. Projectors usually come with a test card that facilitates edge blending or other tasks, and that should be used. Normally, the test card comes with a grid and simple geometric designs so users can make precise, fine adjustments with immediate feedback. Test cards also rely on high contrast, so users don’t have to walk up to the projector and pick out hard to see details. For this reason, it’s less helpful to use a standard image.
2. Arrange the projectors next to each other – The projectors should be set next to each other so that they are on a level plane. If the projectors are level, it will make fine adjustments much easier when using the edge blending mode. The projections should be overlapped at this point, even though the images won’t be blended. They will just run over each other, but that’s okay. The edge blending mode hasn’t taken over yet. Most experts believe 10 to 15 percent overlap is optimal, to allow for maximum image size while making the transition between projections as smooth as possible.
3. Focus the images – This is something every projector user should be familiar with, but it’s important to do it now, before blending. Make sure every image is in focus. If one image is out of focus after blending, it will be tougher to bring it back into line.
4. Use the projector’s edge blending mode to define outputs – The edge blending mode works by combining images and automatically adjusting the brightness and contrast values in the overlapped areas. But the edge blending mode needs each projector’s output area defined so it knows where to make those adjustments. This is simple enough, as most edge blending interfaces are intuitive and graphical. In most cases, it’s as easy as drag selecting each projector’s output area and assigning it to that projector.
5. Hit the button and make fine adjustments, where needed – Once each projector’s output area is defined, the edge blending mode will take care of the rest. If, however, there are still some slight differences present, users can compensate for them using gamma, brightness and curve settings. It’s also recommended to boost the brightness of the non-overlapped areas just a touch, as the overlapped areas will feature lighter black colors.

Bigger is usually better when it comes to projections, whether for educational, branding or artistic purposes. And edge blending makes bigger possible, and in a way that’s intuitive for most people. For additional information one edge blending with projectors, contact a reputable A/V integrator.