Home Cinema projector room decoration

All home cinemas fall into one of two categories.

Dedicated - where there is full control of ambient light and the room is only used as a cinema. If there are windows use black out blinds or similar.

General Purpose - where the room has a cinema screen but also has other functions. Like a games room or a living room. Ambient light control maybe compromised by windows or doors leading into a lit corridor etc. 

A dedicated room would probably have a matt black ceiling and the three non image walls would be complementing the image wall with matt minimal reflecting paint. So as not too rely on matt black everywhere for those that find the black too oppressive, just leave the ceiling on matt black and then take an A4 sample card of your screen paint, to your local house paint mixers and get something close with an extra two small squirts of silver. This will provide a relative close compromise of  keeping towards the grey scale of your images reflection.

For a general purpose room you are best with extreme matt, house paint for walls and ceiling. If you can get away with a light grey, which has become quite fashionable, on your walls, that would be favorite. A  matt red or green would bleed  their colour onto reflected surfaces, but a small price to pay for having a large screen experience.