file size

Discussion in 'Digital Point & Shoot Camera' started by mcola, May 31, 2005.

  1. mcola

    mcola Guest

    Excuse this basic question which im sure has been asked before, but i can't
    seem to find an answer anywhere else.
    If my camera is set to a certain resolution, why are the resulting pictures
    not all the same file size?
    mcola, May 31, 2005
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  2. mcola

    nelly bly Guest

    Hi Mike,
    The amount of detail, complexity, and color the camera is capturing in a
    particular shot also helps to determine the file size.
    nelly bly, May 31, 2005
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  3. A non-compressed bitmap (where each pixel is "the same size" - i.e.
    ten times the pixel count will give a filesize 10 times larger)
    would be exactly the same size. For the format used in most
    digicams, JPEG (.jpg), because it allows for different degrees of
    (lossy) compression it will result in different resulting file
    sizes. See
    Rolf Egil Sølvik, May 31, 2005
  4. mcola

    Mike Mills Guest

    Try this experiment.
    take 3 pix at night trying to capture blackness, now put your hand
    over the lens and shoot again.
    check the filesizes.
    Not all black is real black.
    the agony of having 16 million colours!
    As complexity rises the filesize rises too.
    Now check over your biggest filesizes and look at the histogram
    that is available in some viewers.
    See how the energy is distributed across the colour bandwidth.
    Mike Mills, May 31, 2005
  5. Rolf Egil Sølvik commented courteously...
    I pretty much understand JPEG, but this is still a great
    article. Thanks.
    All Things Mopar, Jun 1, 2005
  6. mcola

    mcola Guest

    Thanks all for the replies. As I now understand it, ea. pic has diff.
    degrees of complexity (pixel wise) and thus jpeg compression results in
    differing final file size. But all pics taken at a certain resolution will
    have the same number of pixels in raw format and thus the same sharpness
    qualilty. Basic, but correct explanation? Thanks again, Mike
    mcola, Jun 1, 2005
  7. Mike,

    Your summary is correct. I use a Canon camera and always use the raw
    format (CRW files), and thus the file sizes are always the same.

    Got digital photos? Show them off!
    Charles Kerekes, Jun 9, 2005
  8. Yes and to see how jpegs work, take a noisy picture (highest ISO and long
    exposure) and you will often produce a larger file. The noise (fine
    details) produced by the high ISO is more difficult to compress.
    Charles Schuler, Jun 13, 2005
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