No problem. Here
is an early pre-finished bedroom conversion I did as a temporary solution until my basement project is finished.
The room is about 14'L x 12'W. Part of the room's length has a tapered ceiling. The paint was a Sherwin-Williams. I found an acceptable color (blue-purple) and bought the darkest shade they could make. I then rented a spray-painter from Home Depot and sprayed the ceiling, walls, doors, window, and all trim.
The actual screen wall has flat-black paint and I can use it as a reference point (of sorts) for 'blacks' in movies. The screen itself is a Draper M1300 100" NTSC (meaning its 4:3, 80"W x 60"H) with about 1.3 gain. The screen is mounted onto a Draper Cineperm tube-frame. The carpet is jet-black, which replaced the stock contractor off-white carpet.
Because of the proximity of the adjacent walls/ceiling to the screen wall in some moderately-bright or brighter scenes the paint's sheen, which is flat, still offers up reflection of light coming off the screen. This illuminates all other room surfaces and, as you can imagine, get reflected back onto the screen as well as directly into my eyes.
I believe that the professional that calibrated my CRT projector measured about 14 foot-Lamberts maximum (100-IRE full-field test pattern). I have wondered if going 'all black' would help, but I think that at this stage of brightness from the projector its the surface reliefs that are doing the majority of the reflection of light. Maybe black velvet all over the walls/ceiling ... as I wouldn't be the first to do that.