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Managing Projector Image Distortion

Take a look at the image above. Do you see the stone at the center of the arch? You know, the one with the arrow pointing right at it?

Well, in the world of architecture, which is several years older than the audiovisual world, they call that center stone (as you can tell from the image) a keystone.

Look closer. Now, where have you seen that sort of trapezoid shape before? Here’s a hint – think about the last time you set up a projector on a conference room table.

You may have tilted the front of the projector upward to get the image higher on the wall. Maybe added a book under the front for a little more tilt. And voilà. There up on the wall…your PowerPoint presentation, nicely distorted into the shape of a keystone.

In the audiovisual industry we call that “keystoning,” a term used for any projected distortion – up, down or even horizontally when the projector isn’t parallel to the wall. Your audience, however, will probably just call it annoying.

There’s a fix for that.

Fixed keystone correction lets projectors project their images upward without physically tilting the projector. The projector’s specification sheet will tell you the maximum angle before distortion sets in.

Once you’ve hit that limit, your next line of defense is digital keystone correction, which is a function of the projector’s scaler. It will digitally correct keystone problems.

Most of the newer projectors will have these capabilities, however they generally will not have the ability to compensate for horizontal distortion – you might want to check out some of the products that are considered to be the Best Video Projectors you can buy to see if they have the capabilities and features you require.

That’s the good news.

The bad news is that using the scaler to digitally correct keystoning introduces its own problems. While the image will be perfectly shaped, the image itself will have noticeable distortions and artifacts.

But, there’s a fix for that.

Rather than propping up projectors and having them take up space on conference room tables, you can have them installed so they are either hanging from the ceiling or concealed in other parts of the room. However, you will want to put that kind of installation in the hands of a professional A/V systems integrator to ensure everything is perfectly measured, calculated and adjusted. By turning to a company like ExhibitOne, you can bring picture-perfect presentations to your audience…and leave the keystones to the architects.


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