Projector Blending

"Don't cross the streams. That would be bad."
Or is it?

Putting aside my poor Ghostbusters joke we are going to talk about the world of projector blending. What is it and why do it? We hope to answer these questions here today.

In many spaces, it’s hard to know what to do with a large stage area. Updating with new set pieces and lighting is expensive and time consuming. It’s also necessary to work around existing displays being used in the space for content. This is why many people make the choice to merge content display with stage design by using a large screen. Often large screens are made up of LED walls which allow custom sizing, and bright, sharp content display. Unfortunately, many times LED wall displays are out of the price range of many churches and other businesses. So, what other options are there?

Enter projection blending. Projection blending is the art and science of connecting multiple projectors to a single system and using them to display a single shared image. Projection blending and multi-screen projection was very popular more than 10 years ago due to the lower lumen output of projectors. By using multiple cheaper projectors, tech teams were able to create a combined, larger screen of high resolution. These setups though, had many reliability issues. They struggled with early versions of ProPresenter, with troublesome triple head 2 go image splitters, and even with bulb-based projectors that were hard to blend and keep color consistency.

Today, the market has affordable high output laser projectors and great modern software like ProPresenter 7 that now makes this cost saving technology a reliable and obtainable option.

The first step to looking at a projector blend setup is screen size. Screen size is important because it determines the number of projectors you will need for the blend. Blends can be as small as 2 projectors wide or two projectors tall. They can technically be as wide as you want, with computer limitations of course. Using an app like BlendZ can help you determine what you need based on your desired width.
​
Now, any projector blend setup requires a ‘blend’ or ‘overlap’ region. This is an area on your screen where what is displayed is doubled so the images can overlap. Ideally, this region is 15% - 25% of the overall image; too little or too much will not allow the image to blend correctly.

Screen material can be a few options, but we always recommend a good quality professional screen if possible as it will help to project a bright and clear image. We also recommend using professional grade laser projectors. These types of projectors don’t have bulbs that need replacing, stay consistently bright, have consistent coloring, and have a higher lumen output in the 6000 to 10000 lumen range. You will want to make sure that all projectors match as much as possible in exact model and age for best results not only with image, but with software.
Once you have a screen and projectors selected it’s important to hang them with precision and use as little image correction as possible. It’s useful in ProPresenter to use the "blend grid" test pattern option for lining up the projectors and overlapping the images correctly. This is a great job for a seasoned AV integrator with experience as it can be very tedious process. It’s important to use a blend app to setup overlap as you will need to put this number of overlapped pixels into a software like ProPresenter to correctly divide up the image across each projector. ProPresenter 7 has some great tutorials available on their website to help. But, once it’s set, it will be relatively easy to maintain.
What’s next? Now that you have a beautiful set of blended projectors on a large screen the last piece of this puzzle will be creating content to fill. Usually, a blended screen has a custom resolution and will not display regular content across its entirety. You will need to either build content or in the case of church worship designs, you can pay for a content service and download the "ultrawide" versions to use.

In our most recent blend project, we filled a large church’s back wall with a 2-projector blend, ultra-wide screen. Both projectors are 1080P creating a nearly 4k wide image spread across the back wall. As the projectors are mounted close to in room speakers, we added vibration absorbing mounts to help keep the projectors from moving once they were adjusted. The large screen filled up some space on the tall stage and is now a great option for scenic back drops to be digitally added rather than constructed. This also created a smaller space below the screen for supplemental stage-based lighting, adding to the aesthetic. This is all driven from ProPresenter with a Blackmagic output card. ProPresenter natively sees the ultrawide screen as a single display to show standard 16x9 content centered or on each side, but also adds the ability to divide it up for different service options. To make control easier we added in a free module called Bitfocus companion to create a single webpage-based button for turning both projectors on and off at the same time. No more messing with remotes.
We loved building this project for our client, and they have loved using it. It’s always fun to revisit an old way of using technology, but adding all the new benefits of updated tech. In this case, it allowed a cheaper way of displaying large scenic content and made it more reliable and versatile. Looking at wanting a LED based display, but maybe can’t afford it? A projection blend could be a great option for you.

Let's Talk!