Plasma technology has certainly achieved quite high contrast ratios, a measure of the blackest black compared to the whitest white. Many plasma display manufacturers boast a contrast ratio of 40,000:1 these days though our tests using a standardized ANSI checkerboard pattern have not proven these numbers out. Plasma displays achieve such impressive black levels by using internal algorithms to block the power to particular pixels in order to render a pixel "dark" or black. While this can limit a plasma television's gray scaling, it does produce exceptionally black blacks - depending on the manufactured plasma display element (i.e. glass). A plasma TV uses maximum power when it is producing full white. As a result, some 2nd tier manufactured brands of plasma TVs have an audible buzz or whining sound when displaying white or very light images.
LCD (liquid crystal diode) displays, by contrast, utilize electric charges to twist and untwist liquid crystals, which causes them to block light and, hence, emit blacks. The higher the voltage passing through the liquid crystals in a given pixel, the more fully those crystals untwist and effectively block light - all of which makes these pixels darker. As opposed to plasma, LCD TVs use the most power when displaying a very dark or black image. This is a difficult process, and despite recent improvements in LCD black levels, only the best LCD televisions have managed to come close to plasma technology in contrast ratio. The one continual drawback here for LCD is off axis viewing, when black levels consistently drop. We have noted some improvement from LCD manufacturers lately in off axis viewing contrast.
ADVANTAGE: Closer than a year ago, but still Plasma. LCD TV manufacturers have made great improvements in black levels and in many cases have nearly managed to match the contrast ratio of plasma TVs. However, Plasma displays still maintain a clear advantage in this category due to fading blacks when viewing LCDs from off axis. For scenes with a lot of dark and light images shown simultaneously - as with content originating from DVDs, video games, and NTSC TV signals - plasmas still consistently outperform LCD TVs.
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