Many people hear the mantra over and over again, and that is "For viewing with total light control, a white screen is best."
Like has been said many times in this thread, yes and no.
Every Home Theater setup is different. Even if two people lived in a housing development where the contractors built all the houses with the exact same floor plan, and two home owners decided to build Home Theaters in the exact same room, and set them up exactly the same with the exact same projectors... it is highly unlikely that they both would have the exact same viewing tastes. (I think I just used my yearly quota of that word in one sentence!)
The new digital projectors are bridging the performance gap between them and CRT projectors with each new model that comes out. As much as people hate to believe it though, CRT is still king in many ways. It produces stunning images with brilliant whites and deep dark blacks that even the best digital projectors have yet to match. Some are getting close, but they still haven't reached that level yet. Their size and typically low lumen output is the biggest detractors of the mighty CRT projectors, and that is where digital reigns.
There is a larger majority of people out there with older projectors, or newer projectors that are more of the budget variety. These projectors are still very good units, but they cannot produce the blacks of the much more expensive models, which as stated still have yet to match CRTs. For some people blacks are a crucial element of what they desire in a projector image. Gray helps in this area even with lights off. True a white screen is the most accurate at reproducing the image the projector puts out, but if that projector doesn't produce stellar blacks, even with light control some people may not be satisfied.
As stated, white is the most accurate at reproducing the image, but it doesn't have to be that way. A neutral gray will absorb some of the lumen's the projector is throwing at it, but reflect the colors back with the least amount of color skewing than other grays that are not very well balanced. This makes the screen more efficient too so the image will be slightly brighter than an unbalanced gray close to the same shade.
A person with total light control won't need as dark of a gray as someone viewing content with some ambient light. This part is a juggling act and is where the lumen chart will come into play when it is finished. A gray in the N9 shade is sufficient to give a projector deeper blacks than a pure white screen while retaining a bright and vivid image where the colors remain true. N9 is actually a very light gray, in fact some commercial screen manufacturers sell white screens that are actually a very light gray. (The High Contrast Matte White screen is actually closer to N8 than N9 in shade)
Here is N9 again. As it can be seen this is a very light gray indeed.
Here are some lights out images with a gray screen.
Sin City is a tough movie to shoot because of how Rodriguez filmed it. He used black and white with with computer enhanced bold vivid colors only on certain elements of the image. Some may initially say the shadow detail is poor in that shot, but that is a very true image as compared to what I see on my HDTV. Any problems with shadow detail is a fault of my projector only having a 250:1 CR. Now look at the image again, especially the wisps of hair. The detail is very much there, as are the colors, image brightness, and the blacks are very deep and dark.
What about the whites?
So one thing to remember about forums, is there will be many people giving advice. Most of it is actually very good advice, some is good advice with personal preferences and opinions mixed in. Everyone has the best of intentions, but as I pointed out with the example of the two home owners, their tastes just may be very different from your own. Like me, I love deep blacks and prefer watching movies with the lights out, but I personally prefer a gray screen... someone else may hate it and swear by white only. The key is to determine what shade of gray your projector can handle without the whites becoming muddy, and the colors dull. From there only you can decided whether you prefer a white screen over a gray screen, but don't totally discount gray just because you have a dedicated HT room.
tomorrow night, how to determine if gray is for you...