Darkening the WHITE Walls Either Side of My Screen

[kopkiwi]

Any suggestions? Unfortunately I am renting so cannot apply anything perm.

Just wondering what sort of products are out there that I can use to put on the very white walls either side of my screen?

The glare that comes back off the walls creates a lot of washout on the actual image. I have the Optoma HD66 and was expecting a light cannon of a projector. Thus far haven't really been impressed with the brightness, I am expecting that this is because of the amount of glare bouncing back from the immediate walls.