Improved contrast with backlighting?  

I don't know what you mean by "void" area; however, you should expect about an 8% reduction in reflected light from a perf. screen. Now, on the other hand, your eye cannot perceive a difference in brightness of less than about 10%. (The difference between dimming a light to 90% bright versus 100% is not realized by you ... only the power company.)

The point about lights in the room (FPTV/RPTV) is a careful balancing act between picture quality and fatigue. Any light *you* can see in the room is also being "seen" by your screen. For example, if you can stand at the screen, with the lights dimmed to "movie" level, and you can tell the walls are red, you have red reflected light on your screen as well.

The degree to which that will affect picture quality is a variable from venue to venue. If any of you have had a FPTV/RPTV calibrated, it was done with zero light in the room.

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D. Erskine
DEsign Cinema Privee
www.DEsignCinema.com
Imagine what you could do, if you could do all you imagine.

Did someone interpret my post to mean, no lights on in the room? Not my intent. One must be careful as to how it is done.

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D. Erskine
DEsign Cinema Privee
www.DEsignCinema.com
Imagine what you could do, if you could do all you imagine.

Peter:
I cannot confirm your findings regarding a perforated screen having a better image. At least not in my setup. Accidently I got at first the Audio Vision fabric instead of the Da-Mat fabric for my screen. And as I have already found out with a screen sample some time ago, the image looked worse. I cannot really define what was wrong, but the image looked kind of strange. Not as good as with my tempory setup slide screen. It looked like a lot of detail had been lost. It was also some kind of soft. I always hunted for the sharpness control of my Pioneer 717 player, but there was a considerable tradeoff here. Either a soft image or some nasty artefacts. I was far from happy. A closer inspection showed that the DLP pixels had nearly the same distance as the holes in the screen. Sometimes a complete pixel row or column hit the holes. This may have caused the loss of detail. Annother point was that I could see the perforation slightly from my normal viewing distance. This may have caused additional distraction because I am very sensitive to regular pixel structures.
Now I have replaced the screen with the non-perforated one and everything looks much much better without any electronic sharpening.

This all said, I would recommend that everyone considering an acoustically transparent screen should test at least a
screen sample with the own projector and look from normal viewing distance. A AT screen may help to increase the perceived contrast as Peter described, but it may also cause other problems depending on the projector used.

Emil

Peter:
The Da-Lite Audio Vision Screen has a similar hole layout like in the negativelightmatrix file. But in contrast to your example the ratio between hole size and pixel size is approximately 1:9 with my setup with a XGA projector. You seem to have much larger larger pixels (1:25?). This comes from using only SVGA projector, projecting a larger image, or having smaller holes. In my setup I just loose to much information when a pixel hits a hole.

Emil

[This message has been edited by Emil Naepflein (edited January 13, 2000).]