Canon IXUS (Elph) - Compression Affects Image Quality??

Discussion in 'Digital Photography' started by Steven Wandy, Jun 11, 2004.

  1. Steven Wandy

    Steven Wandy Guest

    I have the 410. Have you printed out any of the images or just looked at
    them on a computer screen? Depending on your eyesight - and your tolerance
    level for clearity - I think you would see a difference. It might not be
    major - have not tried this with the Canon yet but have tried it with many
    other digital cameras over the years - but it will be there. Take some
    pictures with lots of details (trees work well) and print them at different
    sizes. (Or better yet, crop out the center 25% of the images and then print
    them out.)
    Steven Wandy, Jun 11, 2004
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  2. Steven Wandy

    JC Guest

    I've experimented quite a bit with my Canon IXUS 430, and I'm not
    totally convinced that the compression setting affects image quality.
    For example, a series of pictures taken at size M1 (biggest medium
    image size), with compressions of Superfine, Fine, and Normal, all
    seem to result in pretty much the same image quality, just different
    image sizes on disk. Any thoughts on this?
    JC, Jun 11, 2004
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  3. If you have Photoshop or similar image editor, here's a useful trick:
    take a low-compression and high-compression image at the same size, and
    calculat the difference. The result will show you *where* the two
    images differ. Then look in that region in the two originals. If,
    knowing where the computed differences are, you still can't see any
    significant visible difference, then the higher compression image is
    fine for you. But I suspect that, once you know where to look, you will
    see some differences.

    If you can't see the difference, then use the lowest quality to get more
    images on the card. But I can see the difference between the quality
    levels, and I always shoot at Superfine Large (max size, minimum
    compression). I can't *always* see a difference, but with some subject
    matter the differece is visible. For example, try tree branches against
    a bright sky. I eventually decided that memory cards and CD-ROM blanks
    were cheap compared to the cost of having an image that I want to print
    that was damaged by too much compression.

    Dave Martindale, Jun 12, 2004
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