Just How Important is the Projection Screen?

(Originally published June 14, 2016)

We all know that guy in college that had the projector setup in his dorm room. It was fun for parties and great for playing movies in the background, but the picture never looked that great. The projected image always looked washed out, and you could see every dent and scratch on the wall! But movies shown in theaters today use projectors, and they look amazing! What was college guy’s problem?

It turns out the surface you’re projecting on, usually a projection screen, can be just as important as the projector itself. College guy was projecting directly onto the dorm room wall, where textured paint, bumps, and scratches all act to reflect the light away from the eyes and cause the picture to look dim and washed out.

Light reflects randomly off of a textured wall. 
Source: http://evilrealm.org/

Projection screens are designed to reflect the light directly back to the viewer, which keeps the image nice and bright. However, there is a tradeoff: the more directly the light is reflected back (or the higher gain), the maximum viewing angle is reduced. In contrast, a screen with perfect diffusion would allow viewing from much wider angles, but the overall brightness would be reduced.

A screen with perfect diffusion would look great from any angle, but brighness would be lower from any specific point. A screen with high gain would look very bright when viewed from the center, but the screen would not be viewable form other angles.
Source: www.projectorreviews.com
Modest gain screen vs high gain screen. 
Source: www.projectorreviews.com

Projector “uniformity” refers to the brightness of the image across the entire screen. In other words, are the corners of the image as bright as the center? While this is mainly driven by the quality of the projector itself, projection screens can help to diffuse the light more evenly. Some screens add an optical coating to increase the total light uniformity.

A projection setup with good uniformity would fill the entire screen evenly. Source: www.mycockpit.org

Finally, projection screens play a large role in maintaining image contrast. Since projectors do not actually produce the color black, a projection screen is required to keep contrast high, especially in an environment with ambient light. High contrast gray screens work well in this situation. The gray screen absorbs ambient light that a white screen would reflect back, and in doing so, the black level on the screen is maintained.

Gray screen (left) vs matte white screen (right). 
Source: www.projectorreviews.com

The point is, a great projected image is much more complicated than simply pointing a projector at a wall! As we continue to develop SPUD, we are considering all of these aspects of the projector-to-screen setup to ensure the best viewing experience. You’ll always have a great picture wherever and whenever you want!

Originally published at www.arovia.io.

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