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Gamma correction

Discussion in 'Electronic Design' started by [email protected], Jan 25, 2009.

  1. Guest

    I have this small lcd display
    http://www.sharpsme.com/Page.aspx/europe/en/part/LQ043T3DX02/
    and i've read something about gamma correction (correct me if i'm
    wrong)....In lcd display gamma correction is performed by lcd drive
    circuit: it applies an ac voltage in lc cell to obtain desidered
    Transmittivity/voltage characteristics (transmittivity/voltage without
    correction is a sigmoidal fuction). How can i know corrected function?
    is it linear or power-law (as crt)?
    Another question:
    i've read this relationship:
    backlight_luminance*transmittivity=output_luminance. If transmittivity
    is a linear function, when is more useful a contrast change respect to
    a backlight_luminance change? Backlight_luminance change is more power
    saving, so i can obtain the same output result with less power...or
    not?
    Thanks for the help (i'm new in this field, so excuse me for the
    questions)
     
  2. Guest

    Do you know any link and/or tutorial about its correct use?
    I don't undestand: the output effect should't be the same?
    :)
     
  3. Jasen Betts

    Jasen Betts Guest


    do a linear ramp and a black & white Burkes dither of a linear ramp adjacent in the same
    image adjust gamma until they agree.
     
  4. qrk

    qrk Guest

    There are many web sites with gamma charts. This site gives info on
    gamma and has a few charts about midway through the article. Look
    around enough and you'll find different types of charts.
    http://www.normankoren.com/makingfineprints1A.html

    If you need to adjust gamma on your monitor, you'll probably need to
    do it though the graphics card driver. I'm finding that some LCD
    panels don't do brightness and contrast properly. Most modern graphics
    drivers have gamma adjust burried somewhere in there menu structure.
     
  5. Guest

    Thanks everybody for the help....
    Ok, i understand now, but i'm not able to apply this answer in this
    function
    http://img401.imageshack.us/img401/1339/functionrq3.jpg
    with b[0;1] =backlight factor=luminance/maximum luminance
    If contrast changes, dt(x)/dx changes....what happens if backlight
    varies?I shoud obtain (in agreement with your answer) an offset in
    luminance function, but i'm not able to display it....
    Thanks
     
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