I have a homemade screen with 2x6's and blackout cloth mounted on the wall. Current wall color is white, but I am thinking of painting it a dark red or burgundy color. My question is will the dark paint color make the picture on the screen darker? If so what have others done to prevent this? My option so far has been to mask off the screen and paint around it, but this could be a problem if I decide to go with a larger screen in the future. Any other options/advice? Thanks in advance.

Generally people paint their walls / ceiling darker colors to "absorb" some of the reflected light. It has to do with perception, reducing the amount of light from sources other than your screen will make it appear to be brighter. Another question, did you put a black "felt" border around your screen, that also can minimize the amount of light reflection.

I don't have black felt around the screen. That was one of the reasons for painting the wall, for the contrast. If I paint the entire wall, including behind the screen, will it darken or fade the picture?

screen picture shouldnt be darker if you paint your walls a dark color, if anything perceived contrast should improve.

analogy would be looking at a flash light with the lights on vs the lights off... same light output, but seems brighter since the lights are off... its a win/win situation. better picture and better looking walls.. who likes white walls?