Plasma vs. LCD: Black Level
Contrast ratio is the measurement for a television that determines how many shades of gray are available on a particular display. This is often referred to as "black levels." A television with good black levels will show inky blacks without sacrificing shadow detail. Different television technologies offer various levels of contrast quality. Currently, there are two competitors in the high-definition TV (HDTV) market: plasma and LCD.
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The Contrast Controversy
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Television manufacturers employ different methods when measuring contrast ratio. There are no industry standards in place for contrast ratios, leaving the numbers printed on advertising subjective. Without having the right equipment, consumers shopping for a new television should rely on their eyesight rather than the numbers on the stickers.
LCD
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LCD televisions have less contrast ratio than plasma displays. CCFL backlit LCDs use fluorescent tube light bulbs to illuminate portions of the screen. These light bulbs run horizontally across the television and always remain lit.
Though the CCFL lighting dims certain portions of the screen, its fluidity is diminished because of the heavy reliance upon the LCD panel to block light. For instance, when watching movies with both dark and bright parts in the scene, the fluorescent light can only dim its particular section of the television. All of the other lights have to compensate brightness levels to match. The LCD panel's ability to block light effectively determines the overall contrast.
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LED LCD TVs
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Local dimming and edge-lit LED LCD TVs show a significant improvement in contrast ratios over traditional LCD televisions. On a local dimming LED LCD display, LEDs control smaller areas of the screen. This prevents light seepage through the LCD panel by reducing the overall light needed to illuminate brighter areas of the picture.
Edge-lit LED LCD televisions do not have the contrast ratios as local dimming TVs but they are still a big improvement over CCFL backlit LCDs. This is because LEDs can be turned completely off while the television is on and the backlighting does not run the entire length of the screen.
Plasma
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Plasma televisions still dominate in the area of contrast ratios. The pixels on a plasma TV control color and brightness and do not rely on backlighting to illuminate the panel. This means that each pixel has the ability to turn itself off independent from the other pixels.
The pixels on a completely black portion of the screen will turn off. While some pixels display blacks as lighter shades of gray, the other pixels can provide full illumination in the same scene.
Conclusion
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The ability to control each pixel independently is what makes plasma the leader in contrast ratio. For an LCD television to compete, over two million LEDs would be needed to backlight each pixel. While LCD televisions have come a long way with the new LED backlighting, plasma still offers much better black levels.
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References
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Comments
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oceanwaves77
Jun 13, 2010
The conversation is stupid because no matter how well of a job the local dimming does on LCD, you will always say the plasma is superior because you are aware of the fact that when it's a dark scene, it's really off on the pixel. Because of this, you will never fairly compare the two, but simply state which one did black better in a technical sense. And most people who write about this will only be plasma owners. I can almost bet you have a plasma. But that doesn't mean it's a better TV. It just means you want your plasma to rule. Fact is if a TV can achieve 99% of the perfect black effect, there is no real point in the last little bit if there are other downsides to plasma and there certainly are. This is the reason most manufacturers are abandoning plasma. Higher manufacturing costs, running hotter, having problems with burn in, and longevity issues, lower resolutions are... -
oceanwaves77
Jun 13, 2010
cont just a few. And you wouldn't need 2 million pixels. Yes, technically if you care about making sure each black pixel is independent, but no one can even see that. We aren't talking about bright red, or white pixels glowing here. We are talking about the dark shadows and blackness. A small zone will suffice to produce an image that probably even you couldn't tell apart from a plasma to save your own tv in a bet. Assuming you don't cherry pick special images etc. But then this would ONLY happen when some huge portions of the screen where black or nearly black. In that case it appropriately dims. Something you will struggle very hard to find. If anything if plasma wants to compete with the new LCD's it will have to do something fast as I see it as a sinking ship. Blackness this, blackness that. Blackness is NOT everything, nor is it the major factor. Especially when...
