Canon vs Kodak jpg file size very different

Discussion in 'Kodak' started by Louise, Mar 26, 2005.

  1. Louise

    Louise Guest

    I have a Canon S400 which is 4 megapixels. A friend just purchased a
    Kodak CX7430 which is also 4 megpixels.

    We both use what appears to be the "best" quality settings. I take the
    same shot with both cameras.

    Both cameras produce an image size of approximately 2200x1700.

    On download from the memory card(s) to the computer however, each camera
    produces a radically different size jpg file and the larger, of course,
    seems to produce a more detailed picture.

    Canon - 1743kb
    Kodak - 736kb

    Why would two cameras, both with the same number of pixels, both
    producing a very similar image size, then produce jpg files of such
    totally different sizes?


    Louise, Mar 26, 2005
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  2. Louise

    Ron Recer Guest

    JPG files use lossy compression. The higher the compression, the more
    detail is lost and the smaller the file size. PhotoShop Elements allows for
    12 compression rates and you will get a different file size for each. The
    Canon apparently uses less compression than the Kodak, thus more detail and
    larger file size.

    Ron Recer, Mar 26, 2005
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  3. Louise

    Ron Hunter Guest

    Because JPEG compression is subject to various parameters which affect
    the compression, thus the size of the file. It's what JPEG DOES. The
    Kodak camera compresses more, giving a smaller file, but somewhat less
    quality for that savings. Some would say Kodak was a bit overzealous at
    conserving flash card space.
    Ron Hunter, Mar 27, 2005
  4. Louise

    Louise Guest

    Thanks everybody - it's very clear now. I'm glad I have the Canon and
    not the Kodak. And the next time I purchase a camera, I'll make sure it
    has a raw mode as well.

    Louise, Mar 27, 2005
  5. Louise wrote:
    Louise, if you take the same photo with each camera - can you see the
    difference in the JPEG compression other than in the file size, under your
    own typical viewing conditions? If so, then the Kodak is over compressed,
    if not, then the Canon has too little compression.

    Remember that JPEG is designed so that the compression it does is
    invisible - but the visibility of the artefacts will depend on viewing
    conditions. Print and view a 6 x 4 inch and an 8 x 10 inch image - you
    will likely be more critical of the larger image because you view it
    closer - i.e. the image diagonal will subtend a greater angle.

    What I am saying is that there will be an optimum JPEG compression for
    each circumstance. Go beyond that and you are simply wasting memory.
    David J Taylor, Mar 27, 2005
  6. Louise

    Ron Hunter Guest

    In 99% of the cases, the advantage is with the Kodak and its higher
    compression. As for raw mode, be prepared to WAIT between shots, as
    long as 30 extra seconds, as the raw file gets written to the flash
    media. It's a great feature, but only on a camera that has a very large
    ram buffer, or a very fast flash card, and card interface.
    Ron Hunter, Mar 27, 2005
  7. Louise

    Ron Hunter Guest

    In a few (very few) pictures I have taken, the Kodak compression becomes
    a problem. More often (99% of my pictures), it is an advantage is
    saving storage. I would say that if you take a LOT of pictures of trees
    and grass, you might want to avoid the Kodak cameras before the DX7440,
    which has an optional 'fine' compression.
    Ron Hunter, Mar 27, 2005
  8. Louise

    ASAAR Guest

    Louise, I'm not familiar with your Canon S400, but with several
    cameras that I've used (Canons and Fujis), the highest resolution
    settings had multiple jpg compression levels available. Two for the
    Fujis and three for the Canons. The S400 may only have one
    compression level, but if you aren't completely sure, just check the
    manual. The camera's menu may not make it obvious.

    Also, before selecting a new camera based on whether it has a RAW
    mode, make sure it's not going to be impractical to use. My Fuji,
    for example, requires lots of PC processing before you can see or
    use any of its raw images. And using a 500MB card that can hold
    either 268 or 532 of the highest resolution images (depending on the
    compression that was selected), if raw mode is used the card would
    only be able to hold 61 images. Some cameras may also not be able
    to take successive pictures rapidly when shooting in raw mode.
    ASAAR, Mar 27, 2005
  9. What camera takes 30 seconds to write a raw file?

    My old Canon G2, using an older standard-grade (not fast) CF card, takes
    a few seconds to write a raw image. It's longer than a JPEG image,
    certainly, but it's on the order of 5 seconds not 30.

    Dave Martindale, Mar 27, 2005
  10. Louise

    Larry Guest

    The longest wait in the industry (I think) is the Sony F 828 with a 12 to 13
    second delay while writing a RAW file (It seems like MUCH longer, but it
    Larry, Mar 28, 2005
  11. Louise

    Ron Hunter Guest

    And that is how may megapixels?
    Ron Hunter, Mar 28, 2005
  12. Louise

    Louise Guest

    Oh - 61 images isn't very much. I guess I will consider that when I
    think about wanting RAW.

    Louise, Mar 28, 2005
  13. Louise

    Ron Hunter Guest

    Don't worry too much as large capacity cards keep getting cheaper (and
    we hope faster).
    Ron Hunter, Mar 28, 2005
  14. It's 4 MP.

    If you assume that 8 MP cameras have no faster interface to the CF card,
    you might extrapolate that 8 MP would take 10 seconds for a P&S camera.
    Some DSLRs have more pixels than this, but they also have faster card
    interfaces and larger RAM buffers making this less of a problem.

    Now, how about an example of a camera that takes anywhere near 30
    seconds to write a RAW image of any size? Actually, you said "30 extra
    seconds", not "30 seconds", so you must believe that there is some
    camera that takes 30 seconds longer for RAW than for JPEG, and thus more
    than 30 seconds total.

    Dave Martindale, Mar 28, 2005
  15. Louise

    ASAAR Guest

    Hmm. Why am I not surprised at who has given contrarian advice?
    :) There's no reason to worry, but my recommendation still holds,
    even if it's used 10 years from now. If making a purchase based on
    the fact that a camera has RAW mode, even far in the future, make
    sure that it's not going to be impractical to use. Yes, cards will
    be larger. But sensors and image sizes will also be larger,
    somewhat canceling the advantage of larger cards. And if the camera
    will often be used for action photography, RAW pictures may (or may
    not) slow the camera down. Again, try to know exactly what you're
    getting. It's better for the blood pressure to get the facts
    before, not after the purchase.

    Returning to a familiar topic, who knows but that in several years
    cameras might be able to take 500 pictures using a single AA
    battery. In support of this contention, Sony makes minidisc
    recorders (that use very small magneto-optical discs), that can
    store up to 45 hours of stereo audio on a single disc with very high
    quality, easily comparable to FM stereo at the highest compression
    levels. I believe this to be higher than 20:1, much more than the
    compression used in cameras. Even with this high compression that
    adds to battery consumption, these MDs can play up to about 24 hours
    - and this is from a single alkaline AA battery. While you can't
    get as many hours when recording, writing to the disc probably
    requires more current than writing to a flash card since the disc's
    surface must be heated for recording to occur. Even then, a single
    alkaline battery can last up to 9 hours when recording. Think of
    how many pictures a camera could take in only one hour of operation.
    Mine can continuously shoot 1.6 frames per second. But allowing for
    frequent pauses to select different subjects the average could be
    reduced to 1 frame per second. That's still enough to take well
    over 3000 shots, far more pictures than you or I take in a year!
    Even if AF and zooming had to be replaced with manual focus and
    zooming (which I'd prefer, actually) to get so many pictures from a
    single battery, it would be quite an achievement, and not as
    improbable as 'common sense' would have us believe.

    Maybe Sony should consider putting a minidisc in their cameras.
    That's not entirely unreasonable, as there's at least one MD
    recorder they make that's extremely thin, probably taking up 1/3 or
    1/4 the volume of a moderately small camera such as Canon's A80.
    And 1GB minidiscs are far cheaper than the smallest, most
    inexpensive CF or SD card.

    But no, I don't think Sony will consider doing anything this
    radical. It would be nice if they did though. Optical discs are
    much more rugged, and supposedly have much longer archival life than
    ASAAR, Mar 28, 2005
  16. Louise

    Ron Hunter Guest

    You make many assumptions, many of which aren't true in general.

    It takes my camera about 25 seconds to write 6 jpg pictures to the flash
    card. The files are about 1 meg each. Given a write speed in that
    range, you figure out how long it would take to write a RAW file from a
    camera with 8 MP. If you snap pictures until you fill the camera's
    buffer, it will probably take at least that 30 seconds before it has
    emptied the buffer to the card, UNLESS you have a very fast camera, and
    a very fast card. So the warning is well-founded.
    Ron Hunter, Mar 29, 2005
  17. Louise

    Ron Hunter Guest

    I have been expecting to see minidiscs in high end cameras way before
    now. Surely by the end of this year. Other than that, I think you are
    way out there on your speculations.
    Ron Hunter, Mar 29, 2005
  18. Louise

    ASAAR Guest

    Well of course. I didn't say you'd see anything like such an
    efficient camera anytime this year. Or within five, if ever. But
    it's doable today. Might even have been done already by one of our
    "skunk works" if there was a need for it. There are other toys
    that'll keep our attention diverted. Someone, probably Canon will
    soon have a very small camera with a very big 3" LCD, including
    built-in wifi, so you can immediately upload shots to a website,
    etc. Now that's one camera I'm sure won't be used with alkalines. :)
    ASAAR, Mar 29, 2005
  19. Louise

    Ron Hunter Guest

    Uhhh, Kodak has one coming in June, I believe.

    Medical imaging already does some rather interesting things, such as a
    large pill that you can swallow that transmits thousands of images from
    inside your body to a receiver as it passes through the digestive
    system. It contains imaging system, light, battery, and transmitter.
    But it isn't cheap!
    Ron Hunter, Mar 29, 2005
  20. If you extrapolate from your camera (what is it?) to an 8 MP camera, you
    may well get a 30 sec write speed. But, in fact, are there any 8 MP
    cameras that take this long? Or do all 8 MP cameras have faster
    interfaces? I certainly don't recall reading any reviews of cameras
    with that sort of single-image RAW write times. That was my point.
    But the time to empty a full buffer is very different from the time to
    write a single image. I thought we were talking about the latter in
    this branch of the thread.

    Dave Martindale, Mar 29, 2005
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