What does OPTIMIZATION do for the IrfanView JPEG lossless transformation plugin?

Discussion in 'Photoshop' started by Joy, May 18, 2007.

  1. Joy

    Joy Guest

    What does the IrfanView lossless JPEG rotation plugin "optimization"
    actually do?

    When I rotate a JPG digital photograph using the IrfanView "Options -> JPEG
    Lossless Operations" plugin, one of the options is to "Optimize JPG file".

    The IrfanView 3.98 help doesn't explain what it means to "Optimize the JPEG
    file".

    Does anyone know what this "optimization" setting actually does?
    Should we leave it checked or unchecked?
     
    Joy, May 18, 2007
    #1
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  2. Perhaps ask the programmer, or an Irfanview /generic group.

    PS does its 'own' thing.
     
    Sir F. A. Rien, May 18, 2007
    #2
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  3. Joy

    Ron Hunter Guest

    I can't answer your question, but recommend upgrading to the current
    (4.0) version of Irfanview. Don't forget to upgrade the plugins at the
    same time!
     
    Ron Hunter, May 22, 2007
    #3
  4. Joy

    Sachin Garg Guest

    Jpeg is a two step algorithm where first step transforms the image
    into a more easily compressible form and drops visually less important
    information. Second step (huffman) encodes the remaining information
    in as few bits as it can.

    In Jpeg, the Huffman part can either use a predefined set of tables or
    try to come up with custom tables based on what will work best for
    that image. First option is obviously easier to implement and uses
    less processing power so most implementations just do this due to
    laziness and cameras do this to save battery.

    Irfan view's 'optimization' setting makes it calculate and use custom
    tables which means better compression at no additional loss of
    quality.
    I think you can use it safely. Some old or badly written applications
    might not support Jpegs with custom tables but this should be rare.

    Sachin Garg [India]
    www.sachingarg.com | www.c10n.info
     
    Sachin Garg, May 23, 2007
    #4
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