Sure plasma's have good black levels, but don't you care about the whites?

[linkgx1]

Okay, so I've always wondered why LEDs can sometimes look blacker than a plasma. For years I've been told plasmas have superior blacks. But one thing people seems to miss is the white levels. Plasmas dont' have the best white levels compared to leds. The way our eyes/brains work things seem darker depending on the brightness of the image. For example, if you put a grey square in between two black squares the image will look somewhat lighter. But if you but a greay square in between two white ones then it will look consideribly darker than the former.

Why don't people mention this?