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Contrast Ratios

Discussion in 'Projectors, Screens & Video Processors' started by Dr_Mike, Aug 2, 2004.

  1. Dr_Mike

    Dr_Mike
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    Contrast ratios are oft quoted in prjoector circles but I don't find them particularly meaningful without a reference point.

    Anyone know what sort of contrast ratio the average cinema would get with a film projector or what you'd get with a typicall TV set (CRT) ?
     
  2. DVDcake

    DVDcake
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    I read this somewhere once. IIRC a CRT television typically has a contrast ratio around 3000:1 and cinema film over 10000:1, but don't quote me. :suicide:

    Of course this is assuming a perfectly set up TV and film viewed in blackout conditions without ambient light. This can washout even the best film projection and cause reflections off a CRT thus lowering the contrast.
     
  3. Dr_Mike

    Dr_Mike
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    Thanks,

    So even state of the art digital projection still has some way to go to match film like contrast levels (on paper at least). I suppose it depends at what point you stop noticing the difference.

    The "dye" or whatever you call it in celluloid film must be pretty amazing to block out all but 1/10000 of light shining on it in the projector
     
  4. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    Actually I'd think that on/off contrast of a normal TV would be more like 30,000+:1

    Dr Mike you are correct to be wary of contrast ratios.

    There are lots of ways to measure contrast and it in itself is not a guarantee of quality. You could for instance have a contrast of 10000:1 (full on/full off) on a display but it only be able to show two light intensities....full on or full off. Measures great but would look rather broken. This is an extreme example of course but colour gammut, ablity to show graduations of colour/brightness, contrast, absolute level of black, pixel density (in fixed pixel ddevices).....they all have major parts to play in image quality.

    Gordon


    P.S. Do you think that marketing depts mean full on full off to be
    1> Maxmum light output with input 100ire signal and unt calibrated to be at correct colour temperature and no clipping of detail against light level when fed 0ire signal when exhibting no crushing of black level detail.
    or
    2> Light output at max contrast and nutter high temeperature against unit turned off with mains removed and no light coming out........

    ;)
     
  5. Dr_Mike

    Dr_Mike
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    From what I've read, I think most manufacturers massage their CR figures at least a little bit. a common trick seems to be to measure white level with the iris open and black level with iris closed down.

    I was really going off the independently calibrated CRs on sites like http://www.cine4home.de . The best LCDs seem to be currently around 1,200:1 (TX100) although this is with additional filters to correct the colour. The newest DLPs (and Sony Qualias) seem to be between 2,000:1 and 2,500:1

    So still some way short of film, but could the average viewer tell the difference between 2,500:1 and 10,000:1 ?
     
  6. DVDcake

    DVDcake
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    To win the money, i'll take option 2. :D
     

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