I have noticed this problem: using DXVA acceleration under winXp, and often even w/o DXVA, will result in wrong levels: 16-235 insteadof 0-255. mplayer classic can correct this, but it's pixel shaders are too complex for our gpu. This cause black to appear like dark grey, white not very white,and generally an image *not* with perfect contrast. I have found a way to correct this! Using the intel utility, set brightness at -16, and rise contrast up of 2!!
EDIT: or of 1, more will enchance brilliance, but it will halter normal desktop colors, so you will have to switch these setting every time you watch a video if use more.