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Contrast Ratio/brightness

Discussion in 'Plasma TVs' started by AGC, Aug 16, 2004.

  1. AGC

    AGC
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    Please help ...

    Can someone please explain what they both mean. ie which is better, 1000:1 or 3000:1 contrast ratio and 800 cd/m2 or 1000 cd/m2 brightness

    To me, these are just different numbers, but what does it really mean in viewing quality?
     
  2. Piers

    Piers
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    AGC,

    The numbers are pretty much meaningless as every manufacturer seems to measure contrast ratio differently. Some compare the light output at maximum brightness against light output with the screen switched off! The real figure that you need is light output at peak white versus light output at full black. It is easily measured with the right test equipment and the results can be interesting when compared to manufacturer's claims!

    cd/m2 are units of brightness. The higher the reading the more light the panel is putting out. Again easily measured with the right gear.


    Piers
    Home Cinema Engineering

    www.homecinemaengineering.com
     
  3. Joe Fernand

    Joe Fernand
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    AGC

    As Piers says were getting into the realms of watts per channel!

    Brightness - most displays these days are bright enough in all but the highest ambient lighting conditions; in fact most displays have the ability to output far more light than you want in medium to low ambient lighting.

    Contrast - this is the important one and as Piers says until everyone adopts one measurement you'll never actually know what to expect by looking through manufacturers specifications.

    As an example lets look at a Series 6 Panasonic Plasma Display - touted by most as 'the' Plasma to have if you want the best contrast in your video picture.

    The TH-42PWD6BX has an indicted contrast ratio of 4000:1 in a Dark room (no ambient light) add in a measly 150 lux of ambient light and the same panel measures at 160:1.

    So not only do we need a standard way to measure contrast we need to look at contrast readings under varying ambient lighting conditions.

    Best regards

    Joe

    PS Any photographers out there jump in with a guide to what 150 lux 'looks' like!
     

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