for archiving to a specific filesize: reduced TIFFs or full-size JPGs?

Discussion in 'Scanners' started by scanubis, Oct 29, 2003.

  1. scanubis

    scanubis Guest

    I'm a newbie to this scanner thing, and I'm just archiving some photos
    (color prints) and will be destroying the originals. Quality isn't
    paramount, or I'd just leave them as their full size TIFFs at 20MB+
    each.

    Source scan is 600dpi
    Processing images with Photoshop 7.01 on Windows XP

    My target filesize is <=2MB, but of course I'd like to maintain the
    very best image quality within this limit, especially for future
    editing or enlargements.

    Realizing that JPG is lossy, but so is image reduction, am I better
    off to keep it in TIFF format and scale the image down (say, to fit
    within 1280x1024) or to maintain the original scan size and simply
    store it in a lossy format such as JPG? In my brief experimentation,
    the latter approach maintained far better detail on zooming in.

    If I go the JPG route, any opinions on which JPG compression level is
    acceptable? I've been using the "7" setting in Photoshop but haven't
    done a huge amount of experimentation yet.

    Any opinions or criticism you may have are welcome.
     
    scanubis, Oct 29, 2003
    #1
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  2. scanubis

    AArDvarK Guest

    You only need 300 dpi (dots per inch) but call it
    PPI (pixels per inch >digital), which is more than
    enough for ink jet printing and just right for chemical
    photo printing. This will cut your sizes in half. The
    uncompressed tiff is perfect for color 'fullness' of
    an original, and the compressed tiff will give you your
    target file size but may not be the color consistancy
    you desire. A 100% or "12" JPG will do better and
    be smaller that an uncompressed tiff, and is not Lossy.
    "7" is definitely far to low.

    DPI is better as a discryption for ink dots, such as
    printing at 1440 x 720 dpi >ink.

    A better size to consider for storage is 1600 x 1200
    as a "12" -100% JPG for full color consistancy.
    That way is it easier to scale larger for printing in the
    future. Experiment further.

    Alex
     
    AArDvarK, Oct 29, 2003
    #2
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  3. <scanubis> wrote in message
    SNIP
    In your case I'd go the JPEG route. If you downsize/rescale later, you can
    somewhat compensate for the loss of color accuracy that's inherent in JPEG's
    lossy compression.
    Depending on the Photoshop version you use, you can "Save for Web" and get a
    preview or before/after comparison, and an estimate of file size. Otherwise
    it's almost impossible to predict the size after compression, because it's
    image content dependent. Lots of detail compresses less than large uniform
    or out-of-focus areas.

    Bart
     
    Bart van der Wolf, Oct 29, 2003
    #3
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