How LCD makers inflate their contrast ratio scores

How LCD makers inflate their contrast ratio scores

Summary: If you've ever wondered why contrast ratios claims of LCD monitors can swing so wildly from product to product, here's the explanation:There are "dynamic contrast ratios" and then there are "static contrast ratios".  Static contrast ratios is defined by the ratio of the brightest part of an LCD screen to the darkest part of an LCD screen that can be simultaneously displayed on the screen.

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If you've ever wondered why contrast ratios claims of LCD monitors can swing so wildly from product to product, here's the explanation:

There are "dynamic contrast ratios" and then there are "static contrast ratios".  Static contrast ratios is defined by the ratio of the brightest part of an LCD screen to the darkest part of an LCD screen that can be simultaneously displayed on the screen.  Dynamic contrast ratios are measured by the darkest dark from one image to the brightest bright from another image being displayed at different times.

This is achieved by dynamically altering the brightness of the entire screen or darken the entire screen when scenes are mostly bright or are mostly dark.  This increases the "blackness" of the screen during dark scenes and it increases the brightness of the lighter scenes.

This effectively allows LCD makers to claim a larger dynamic contrast ratio of "3000:1" as oppose to a static contrast ratio of "800:1".  While this technique can definitely improve the video quality for some mostly bright scenes or mostly dark scenes, you can't actually get that level of contrast on the screen and the actual contrast ratio is not altered.

So when you see these inflated contrast ratio scores, you're not being lied to but the numbers are confusing.  Having an LCD that dynamically shifts brightness is a desirable feature but it isn't a substitute for true contrast ratios.

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  • Frank S

    Sony provides both static (which they call on-screen) and dynamic contrast ratios in their specs. But I notice retailers aren't as forthcoming when they advertise them--you're less likely to see the static contrast ration in a newspaper ad.
    frank_s
  • Kind of, sort of, like RMS vs Peak power ....

    I remember the old days when Monkey Wards sold "800 watt"stereos!
    Yeah, right! 800 watts for 1/10,000 of a second.

    Thanks for the info. Don't let the reindeer step on your toes!
    kd5auq
    • I would say it's slightly better than RMS versus Peak

      I would say it's slightly better than RMS versus Peak, but not much better. There are a significant portion of scenes where nearly all of the pixel data is below the 50% threshold or above the 50% threshold for brightness. In those situations, diming the entire screen or brightening it does significantly improve screen quality. It's just not true contrast ratio and it probably needs to be clearly labeled because consumers are confused by it.
      georgeou
    • not just that...

      also for some specific frequencies, and and without guaranteeing distortion values
      patibulo
  • Good site for real specs?

    I can't seem to find a good easy place to get the real, untouched-by-marketers specs on LCD panels. I'd love to be able to search by things like kind of panel (TN, etc.), contrast ratio (split between these two types), viewing angle, color accuracy, etc., somehow all with quantitative standardized metrics. Probably will be a few years until someone manages that, though. Any suggestions in the meantime?
    AySz88
    • I linked to that in my LCD viewing angle post

      http://blogs.zdnet.com/Ou/?p=930
      I linked to that in my LCD viewing angle post. Just click on the picture and it will take you to http://www.behardware.com/articles/686-8/review-of-the-dell-2407wfp-hc.html. That site has one of the best LCD reviews I've seen. Unfortunately, they don't review every single display.

      Over the weekend I noticed a $499 LG 24" display that uses a superb MVA type screen. The cheap $300 Soyo 24" LCD is also an MVA or PVA but it has no frills and some people in forums questioned the reliability. I'm going to go get one of those Soyos and check it out for a review.
      georgeou
  • ZDNet, Fix Your Stupid Article

    Biometric database article is broken..you'd think they would test their articles before they post them...guess they are too busy deleting people's posts to do that.
    itanalyst
  • Name me ONE product, that ISN'T marketed...

    ...majorly based perceived differences and BS aimed at human insecurity. I'm surprised some SOFTWARE MAKER doesn't proudly proclaim they've been "CFC-FREE, SINCE '83"...
    Look what the auto industry has done to the World. Thanx to them, we've got resource wars and pollution. And this turmoil has only just begun.
    Feldwebel Wolfenstool
    • Ok here are a few

      In a broad category, items that are not marketed to consumers but to the industrial crowd tend not to make grandiose statements. When an industrial electric motor is rated at 2 hp it really is a 2 horse motor. In the consumer realm a lot of exageration does take place. So a 7hp compressor really is 4.5 hp compressor. However I am not so cynical that I believe that is always the case. Many products that I have purchased have performed exactly as marketed.


      Another area would be agricultural products. Typically if you get a tractor and it says it is a 50 hp tractor, it will be a 50 hp tractor, rated at the wheels. PTO horsepower is given as well. They tend to be very specific in how much it will lift, pull, etc.

      for more specifics see www.eatoncompressor.com. They guarantee not exagerations to their specs.
      DevGuy_z
    • I remember...

      way back in the 80s there was some guy marketing software which he claimed evenly distributed the 1s and 0s on your hard drive. His sales pitch was basically that it was possible that all your data might wind up on one side of a hard drive platter, throw the platter off balance and crash it into the heads. People will come up with any marketing ploy if they think it'll make them a buck.
      jasonp9
  • Question about Dynamic contrast

    From the description it would seem to me that what is actually happening would be the same as burning in the bright scenes in a photograph and reducing the print exposure time for the dark scenes. In both cases this reduces the actual scene contrast in the changed area.

    For better pictures, the procedure is to burn in the shadows to bring out what is in shadow and to reduce the exposure of the bright areas to prevent washout of the details. This procedure does have the effect of reducing the overall contrast ratio of the picture, but it does provide much more information about the subject.
    Update victim
  • RE: How LCD makers inflate their contrast ratio scores

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    yman25