Here is what i did that made the demo look pretty sharp. So, i can only imagine that it might work in the full game since i have heard people say that they have needed to bring down their brightness levels.
1)Brightness at around 60-70
2)Bump up the color on your t.v(will give the game a more vibrant look)
3)DO NOT play at 1080i
4)force ps3 to play at 720p or 1080p( I would do 720p since it is its native resolution and not 1080p wich is upscaled)