a
Projector can be very effective, but you are right to be concerned about "projected black".
For any
projector that you can afford, this will be a real concern.
When the lights are on, it will look great. However you will want to use a hard
shutter to
cover the
lens after you
fade the
image out.
There are automated,
DMX controllable products out there for that very purpose. I think
City Theatrical sells one...but it's not cheap, and does not dim.
If you use it while the
image is on, it looks a little like a wipe, instead of a
fade.
When we used
LCD projectors at Cornell U, I made a home made dimming
shutter system based on the old AS100 shutters for Pani Projectors.
Pani used grey scale glass (which we could not afford), but I made mine out of poster-board, and old CD drawers out of "retired" computers. Total cost was about $20 plus a few hours of labor and experimentation.
if you open your hands in front of your
face, and spread your fingers slightly, then move your hands together and apart (one just in front of the other), you can get a rough idea of how it works.
basically I took 2 CD drawers out of old computers, and wired them to a 3 position
switch. then I had open, close, and stop.
on the end of the drawers I attached "fingers" of black poster-board cut in a long zig-zag
pattern, so that as the drawers moved to the open position, the posterboard moved in front of the aperture, thus
blocking the light. The
image was gradually blocked across the entire surface. when the Drawers were fully deployed, no light could get through. when they were fully retracted, no light was blocked. all of this was mounted on a piece of wood that was attached to the same surface that the
LCD projector sat on.
the more acute the angles cut into the paper (so the more "fingers" in the same vertical space), the better the
unit worked for dimming... as long as the shutters can get all the way into and out of the optical path, it works great.
It is not silent.
for a super low budget solution, you can have a flap of posterboard, or a piece of black fabric on a string deployed by a
stagehand in the
catwalk.
Either way, you want to black the
image out when it's not in use.
If you're dimming digitally, then you can just
block the front of the
projector (low budget).
If you make a
dimmer (like the one I describe above),
blackout after the
image is blocked.
I hope that helps.