Why does lossless jpg rotation make a larger file?

Discussion in 'Digital Photography' started by louise, Jan 28, 2004.

  1. louise

    louise Guest

    Thanks for all your responses to my questions about
    rotation.

    I have now tried rotating an image in Irfanview and in
    Adobe PhotoImpressions. I have chosen lossless rotation in
    Irfanview and rotation - best quality, in PhotoImpressions.

    In both cases the resulting file is larger - about 500+ kb
    larger - with the same final size and number of megapixels.

    I think I don't understand the concepts involved and so I
    don't understand why the image doesn't stay exactly the
    same size.

    If data is actually added, does this really improve the
    image I would eventually print or have printed, does it
    make no difference in the image, or what is happening?

    Thanks again.
    Louise ()
     
    louise, Jan 28, 2004
    #1
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  2. louise

    Ed Wurster Guest

    If you know the original JPG quality setting, then choose lossless rotation,
    and save with the same quality setting, the file size is the same.

    I confirmed this with Irfanview.

    Ed
     
    Ed Wurster, Jan 29, 2004
    #2
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