Are white screens obsolete? - AVS Forum
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post #1 of 14 Old 11-04-2000, 10:53 PM - Thread Starter
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After living with a grey screen for several months, it made me ask myself the question, "Why would anybody ever buy an expensive white screen?"

So I though I'd see if I could bait anybody into responding. The vast majority of screens being sold commercially are white.

I can understand those who own CRTs need the extra brightness. In the past two years the need for white has dropped substantially. With the release of brighter projectors, the need for white would seem to be dropping as well. I see that Mitsubishi has started shipping the x400. Even if you aren't crazy about LCDs, the x400 looked darn good in extremely high ambient at Infocomm. Of course it was 3000 lumens into about a 50" screen.

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post #2 of 14 Old 11-05-2000, 11:19 PM
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No

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post #3 of 14 Old 11-06-2000, 07:30 AM - Thread Starter
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MrWiggles,

Given your terse response, its hard to know the basis for your opinion, please let us know,

1) Have you owned, made, or seen a gray screen in action?
2) Own a projector with >1000 lumens?
3) Have ambient in your viewing environment?

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post #4 of 14 Old 11-06-2000, 08:35 AM
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When digitally based projection systems mangage to get TRUE black level, or something so close to it that it nearly a given, then white screens could easily and properly be used with that projection system.

My main comment with the usage of the current examples of digitally based projectors requiring the grey screens deals with the human visual mechanism and the 'falsification' of a 'apparent' black level, thus bringing about a 'apparent' better image with the use of a grey screen. If true cut off is achieved with one of these projection systems, then white once again becomes a extemely valid choice.

CRT= infinte black level, and lmited output, thus white is valid.

Digital= limited black level and an extremely high white level, thus grey is valid, instead of black, as the white level is NOT infinite, and neither end of that scale is 'locked down' as it is in the crt.. the black level.

Due to the 'floating' (meaning well off of a true black, I fully realize that it does not float or move about) characteristic of the black level, and the non-infinite white level, there will have to emerge many different values of grey if the market is to be properly outfitted with the screens that are required for all those different black level/lumen count differences between the various projectors.


what I mean is one man's perfect grey is another man's poor choice.

It MUST be fitted to your projector. A limited range of output means that grey matching is CRITICAL to getting the greatest contrast range possible out of your projector. Compared to a CRT, (at this time) you have very little headroom or room to move in this regard.

I hope to be able to send out 'grey level matching' kits. This aspect is critical for folks. I do not think at this time that the average user or grey screen prospective buyer realizes how critical it is.

That limited contrast range can be destroyed even further by a poor grey choice. you don't need to take a barely realized 300:1 contrast range and halve it by making a poor grey choice.

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[This message has been edited by KBK (edited 11-06-2000).]

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post #5 of 14 Old 11-06-2000, 10:28 PM - Thread Starter
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I agree,

For example, I just got a sample of the new Dalite Gary DaMat. Its just a little bit too dark for my projector. I wonder where the .8 gain number came from, it looks closer to .4. Also got a Super Wonder Lite sample. Its too bright, even though it has a silvery, grayish cast. Should be nice in ambient ,though. It also has some texture and is rated for a gain of 1.8, but appears grayish, when side-by-side with a Kodak 90% white card.

Ideally,if I could have the texture of the DaMat with the silvery reflectance of the Super Wonder Lite with a touch more dark, it would be optimal for my current projector.

My guess is the DaMat needs about 2000 lumens in 100" to be optimal.

Super Wonder Lite is close to Ralph Lauren Candlelight Silver on a cloth base in appearance. Of course, its much more uniform.




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post #6 of 14 Old 11-08-2000, 05:39 PM
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Quote:
Originally posted by kelliot:
I can understand those who own CRTs need the extra brightness.
You make it sound like CRTs "need the extra brightness" and therefore cannot get the benefit of a grey screen, when in fact CRTs DO NOT need grey screens because they can do black.

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post #7 of 14 Old 11-08-2000, 07:07 PM - Thread Starter
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Check out my photos at
http://www.avsforum.com/ubb/Forum9/HTML/000507.html

My point is gray looks much better under modest ambient.

CRTs would have problems handling virtually any ambient light. Which is the problem with white screens. They are inferior at handling ambient without looking washed out.

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post #8 of 14 Old 11-09-2000, 11:15 AM
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"Of course it was 3000 lumens into about a 50" screen."

On a unity-gain screen, that's 360 ft-L!!

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post #9 of 14 Old 11-09-2000, 07:42 PM - Thread Starter
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Noah,
It may have been 360 ft-lamberts but the ambient was very bright room light. The ft-lambert rule of thumb only holds for dark movie theatres.

I was visiting my brother a few weeks ago and went to the KC Chiefs/Oakland Raider game at Arrowhead Stadium. The scoreboard has a very nice outdoor display. I can only wonder at the brightness in terms of ft-lamberts.

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post #10 of 14 Old 11-09-2000, 09:02 PM
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Ken,

Yes, or the displays on the sides of buildings on Tokyo that hold up in direct sunlight.

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post #11 of 14 Old 11-10-2000, 08:12 PM - Thread Starter
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I have a theory that the least objectionable (notice I didn't say best picture) viewing conditions are when the ambient of the room is very close or slightly higher the minimum black level of the projector + screen.

The reasoning (and observation) is that this prevents solid black or mostly solid black scenes from being brighter than the background and it looks darker by contrast.

It explains why even modest levels of gray(.8) in a screen works.

It also explains why my LCD sometimes seems to looks better in very low ambient than in complete darkness. If one varies the ambient, there is a threshold at which the ambient exceeds the black level and the contrast begins to degrade rapidly. This threshold gets higher as projected intensity get brighter and favors brighter projectors with good contrast ratios.

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post #12 of 14 Old 11-12-2000, 09:00 PM
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Ken, I looked at your pictures--thanks for posting them. What kind of projector are you using?

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post #13 of 14 Old 11-13-2000, 07:31 AM - Thread Starter
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I use a NEC MT1040 with a DTC100 and VHDC300 for broadcast and an HTPC for DVD. DILAs are better dut at least twice what I paid for the projector.

Don't forget digital cameras have less dynamic range than one's eyes. The black's look darker in the photo than in real life. Also the screen door doesn't show in a distance photo.

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post #14 of 14 Old 11-13-2000, 01:04 PM
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Ken,

Have you considered backlighting? I use rope light, about 1/2: dia. It looks like your screen plane is a few inches in front of the wall, so it would not wash out the screen.

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