Canon Compression: Superfine, Fine, or Normal

Discussion in 'Canon' started by NadCixelsyd, Feb 18, 2009.

  1. NadCixelsyd

    NadCixelsyd Guest

    What's the difference if I select Superfine, Fine, or Normal
    compression on my new Canon SD880. Yes, I know that Superfine files
    are larger than Fine or Normal, but where is the loss? Is the loss
    obtained because pixels are eliminated? Are the losses due to fewer
    colors?

    I could experiment, but I assume some-of-you pros have some feel for
    what's the best tradeoff between size and picture quality. (I'm
    thinking Fine quality in either 2816x2112 pixels or 3648x2048)

    90% of the photos I take are compressed down to (about) 2000pixels
    wide when I edit them. Should I just set a lower quality? Does that
    cause the same effect?
     
    NadCixelsyd, Feb 18, 2009
    #1
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  2. NadCixelsyd

    OG Guest

    Firstly, I don't know your particular camera, so this is a layman's
    explanation of the basic principles.

    Assuming you are producing jpeg format files, the compression used is lossy.
    All compression attempts to analyse the overall data held in the pixels and
    find an effective means of representing the pixels that uses less data to
    store than is in the original image. Because jpeg compression is lossy, when
    the image is displayed, you get 2 types of changes - in some areas details
    will be lost, and in other areas, artifacts will be added to the image. This
    can be particularly evident in strongly contrasting areas of the image, for
    example branches next to sky etc (you may see the sky being distorted with a
    sort of blocky background)

    If you were to experiment, as you move down the image quality range, you'll
    see more and more artifacts in those areas.

    Since camera memory is relatively cheap, I would recommend saving the images
    at the highest quality settings, because although you can always reduce
    quality to match a required file size, you can never put back accuracy that
    you've already lost.

    Don't forget that jpeg compression takes place every time you save the
    file - so if working on an image, take a copy first, and try to make
    changes all in one edit session with only one save (or save using a
    non-lossy format such as PNG between the original format and the final
    export to jpeg).
     
    OG, Feb 18, 2009
    #2
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  3. NadCixelsyd

    Paul Furman Guest

    With photoshop, you are fine as long as you don't close the file,
    there's only one jpeg compression that sticks then.


    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
     
    Paul Furman, Feb 18, 2009
    #3
  4. NadCixelsyd

    Paul Furman Guest

    The standard DSLR group answer is going to be shoot at the highest
    quality because you never know when that 10% of 'keeper' photos will
    occur. Of course you could have special needs like only posting to a web
    site, just documenting stuff for work, never a need to crop or zoom in
    later, etc.

    The Superfine/Fine/Normal distinction is jpeg compression which saves
    space by abstracting large simple areas of the photo. That can show
    blocky shapes in smooth gradations in an image & decrease your ability
    to adjust exposure & contrast later. The 'pixels are eliminated' in
    simpler parts of the photo, the overall pixel count isn't reduced
    though, just the color information is simplified & made more sketchy. If
    I NEVER needed more detail than a web page, I would chose a smaller
    pixel count before choosing a more compressed file. If I didn't care if
    it looked kinda blocky some times in the blurry areas - as long as I
    could still see all the details in the sharp areas, then I'd go with the
    more compressed jpeg & keep the pixel count maximized. If I wanted to
    take appealing photos for various uses I would maximize everything &
    just get spare memory cards & hard drive to store it.

    --
    Paul Furman
    www.edgehill.net
    www.baynatives.com

    all google groups messages filtered due to spam
     
    Paul Furman, Feb 19, 2009
    #4
  5. NadCixelsyd

    D-Mac Guest

    You arrogant bastard.

    You rewrite the charter for a group to accommodate your own
    anti-netiquette signature line, Cross post all over the planet to
    totally irrelevant groups and have the gall to chastise someone for
    asking a legitimate question.

    Idiots like you are the ones who destroy what they came to enjoy and
    lament on the decline of Usenet in general. Congratulations dumb Canuck...

    You are doing a good job of driving people we desperately need to
    encourage, right off to moderated forums where bigots like you are
    censured... If you ever got allowed in.

    D-Mac.info
     
    D-Mac, Feb 19, 2009
    #5
  6. One area I tend to notice jpeg compression is in hair. With
    low compression (e.g. superfine) you see hair, with high
    compression (e.g. normal or economy) you may see an
    even-coloured area.

    -Wolfgang
     
    Wolfgang Weisselberg, Feb 19, 2009
    #6
  7. NadCixelsyd

    Robert Coe Guest

    NadCixelsyd wrote:
    : > What's the difference if I select Superfine, Fine, or Normal
    : > compression on my new Canon SD880. Yes, I know that Superfine files
    :
    : OG and Paul have answered (I suppose), however this NG is for D.SLR
    : cameras (we tolerate some almost-D.SLR cameras, sort of).
    :
    : For your camera, in the future, the right NG is rec.photo.digital .

    Bullshit. My 50D has equivalent settings. Many settings of that sort are
    similar across Canon's entire product line. The P&S/SLR distinction is
    meaningless for this discussion, so it's just as relevant here as in the other
    group.

    Bob
     
    Robert Coe, Feb 20, 2009
    #7
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