Originally Posted by JohnnyWilkinson
OK, but take an imperfect projector, one which isn't capable of displaying deep blacks.
Darkening the room will likely improve the picture quality to a point, but once you go far lower than the black floor of the projector, it's possible that you risk simply making the flaws of the projector more obvious, right? If the room is perfectly black, the grey 'black' floor of the projector will stand out that much more against the very dark backdrop.
Yah, it's somewhat true, but only on a smaller amount of content.
It mostly only affects scenes just above total blackouts (credits, small starfields, etc...), and even then it is mostly the edges of the image that look too gray rather than the overall image.
Although total blackouts are affected too, I find that most total blackouts happen after a scene that is quite a lot brighter, and in that case everything looks pitch black for a couple seconds until your eyes adjust (because the room is so dark from all the TBV treatments).
Scenes with a lot of stars in them still look better, but if the scene is incredibly dark and your eyes are fully adjusted, the black velvet does have the effect of making the edges of the scene look slightly more washed out on my older JVC. I'm sure with an RS-540/640 it would be much less so.
However, even bright scenes are improved, and most dark scenes, so it outweighs the negatives.