I bought a dvi > hdmi cable to connect my air to the hdmi port of a samsung 46inch tv. The picture is perfect at 1600x1200, but when i select 1920x1080 it looks really bad, sorta like 16bit colors. When I use a vga cable it looks fine at 1920x1080. So what am i doing wrong? or has it something to do with the dvi > hdmi cable i bought?