Resolution or Compression?

Discussion in 'Digital Photography' started by John Wright, Sep 8, 2004.

  1. John Wright

    John Wright Guest

    All digicams provide several resolution levels and compression levels. Using the highest resolution and the lowest compression produces maximum image file sizes. If you wanted to pack more photos into your card, you would have to reduce file sizes by either reducing resolution, by increasing compression, or both.

    When is increasing compression better than reducing resolution?

    And when is reducing resolution better than increasing compression?

    Regards - JW
    John Wright, Sep 8, 2004
    #1
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  2. Reducing either is ill advised. If the detail is not on the chip then it can
    never be in the photo. Don't think of it as a compromise from best
    JPG...best JPG is a compromise. Its best to take RAW files....some cameras
    can't do that so their best is TIF. Both of these take a lot of chip space
    and time between shots so many of us advocate the compromise of best JPG.
    Any more compromise is too much. Buy another chip.

    That being said....try it and see. Take the same shot at all levels of JPG
    and print using a wet process (normal photo print processing) at 8x10 to see
    if you can see a difference. If you start with a 12 mp camera then maybe a
    smaller number of pixels is ok....you don't say what you start with.


    "John Wright" <> wrote in message
    news:413e3ddc$0$15471$...
    All digicams provide several resolution levels and compression levels. Using
    the highest resolution and the lowest compression produces maximum image
    file sizes. If you wanted to pack more photos into your card, you would have
    to reduce file sizes by either reducing resolution, by increasing
    compression, or both.

    When is increasing compression better than reducing resolution?

    And when is reducing resolution better than increasing compression?

    Regards - JW
    Gene Palmiter, Sep 8, 2004
    #2
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  3. John Wright

    Mxsmanic Guest

    John Wright writes:

    > When is increasing compression better than reducing resolution?


    They resolve to the same thing, actually. A highly compressed image of
    large dimensions will be no more detailed than an uncompressed image of
    small dimensions. So it's your call.

    In general, I tend to increase compression when I reduce size, instead
    of the opposite. The logic is that any image that is really small
    doesn't have to have much detail, anyway, since file size is probably
    the real issue, so why not just increase compression as well? For very
    high-resolution photos, I set the compression very low--otherwise why
    bother with the high-resolution?

    Overall, the total amount of information is the same either way. And
    you can tell how much information the image contains by the number of
    bytes required for the compressed file.

    --
    Transpose hotmail and mxsmanic in my e-mail address to reach me directly.
    Mxsmanic, Sep 8, 2004
    #3
  4. "Mxsmanic" <> wrote:
    > John Wright writes:
    >
    > > When is increasing compression better than reducing resolution?

    >
    > They resolve to the same thing, actually. A highly compressed image of
    > large dimensions will be no more detailed than an uncompressed image of
    > small dimensions. So it's your call.


    That would be true if image data were random, but it's not. Most images have
    enormous areas of slowly varying colors and tones. Even landscapes with
    corner to corner detail often have vast expanses of sky.

    As a practical matter, best quality jpeg in photoshop compresses images
    files to 1/3 the size with no visible reduction in detail/quality. And best
    quality jpeg from the Sony F707 was indistinguishable from the tiff for the
    same image.

    > In general, I tend to increase compression when I reduce size, instead
    > of the opposite. The logic is that any image that is really small
    > doesn't have to have much detail, anyway, since file size is probably
    > the real issue, so why not just increase compression as well?


    Bad logic. Small files will almost always be viewed at 100% on the screen,
    so the jpeg artifacts will be blatant. Larger files are usually printed, and
    unless printing very large, quite a bit less sensitive to minor jpeg
    artifacts.

    > For very
    > high-resolution photos, I set the compression very low--otherwise why
    > bother with the high-resolution?


    For files one is going to manipulate, one wants to keep the compression low
    or zero.

    > Overall, the total amount of information is the same either way.


    Again, that assumes that the information in the file is truly random. It's
    not, and there's lots of room for compression. The pixel matrix is a
    horrendously innefficient way to represent images.

    > And
    > you can tell how much information the image contains by the number of
    > bytes required for the compressed file.


    While that's correct in theory, in practice (with digital cameras), the size
    of a compressed file is most closely related to the noise, i.e. the ISO at
    which it was shot.

    David J. Littleboy
    Tokyo, Japan
    David J. Littleboy, Sep 8, 2004
    #4
  5. John Wright

    Hunt Guest

    In article <413e3ddc$0$15471$>,
    says...
    >
    >This is a multi-part message in MIME format.
    >
    >------=_NextPart_000_005B_01C49582.794C7F00
    >Content-Type: text/plain;
    > charset="iso-8859-1"
    >Content-Transfer-Encoding: quoted-printable
    >
    >All digicams provide several resolution levels and compression levels. =
    >Using the highest resolution and the lowest compression produces maximum =
    >image file sizes. If you wanted to pack more photos into your card, you =
    >would have to reduce file sizes by either reducing resolution, by =
    >increasing compression, or both.
    >
    >When is increasing compression better than reducing resolution?
    >
    >And when is reducing resolution better than increasing compression?
    >
    >Regards - JW

    [HTML SNIP'ped]

    It is all a matter of what you can live with. If you are only going to Web,
    then 640x480 (or similar) High JPG compression will probably get you by. If
    you are going to a full-page magazine ad, then none - RAW would be your best
    choice, or, as said above, TIFF. You have to define the end use. Just
    remember, you can't go back, once you choose low rez, or high-compression, or
    any combination of the two.

    Hunt
    Hunt, Sep 8, 2004
    #5
  6. John Wright

    Patrick L. Guest

    "John Wright" <> wrote in message
    news:413e770d$0$18007$...
    > "David J. Littleboy" wrote
    > > Most images have
    > > enormous areas of slowly varying colors and tones. Even landscapes with
    > > corner to corner detail often have vast expanses of sky.

    >
    > > As a practical matter, best quality jpeg in photoshop compresses images
    > > files to 1/3 the size with no visible reduction in detail/quality. And
    > > best
    > > quality jpeg from the Sony F707 was indistinguishable from the tiff for
    > > the
    > > same image.

    >
    > What you say makes sense.
    >
    > Are you therefore saying that where I am forced to reduce the file size, I
    > am *ALWAYS* better off increasing compression rather than reducing
    > resolution? Are there no exceptions to this rule?



    Yes, as long as you do not compress to such a degree that artifacts are
    visible to the normal eye on the target media at a given size.



    I shoot with a 5 megapixel camera, jpeg at 8:1, and get nice 11x14 prints,
    I do this all the time. I can even get a 16x20. You couldn't get a 16x20
    enlargement with a one megapixel tiff.


    Patrick
    Patrick L., Sep 8, 2004
    #6
  7. John Wright

    John Wright Guest

    "David J. Littleboy" wrote
    > Most images have
    > enormous areas of slowly varying colors and tones. Even landscapes with
    > corner to corner detail often have vast expanses of sky.


    > As a practical matter, best quality jpeg in photoshop compresses images
    > files to 1/3 the size with no visible reduction in detail/quality. And
    > best
    > quality jpeg from the Sony F707 was indistinguishable from the tiff for
    > the
    > same image.


    What you say makes sense.

    Are you therefore saying that where I am forced to reduce the file size, I
    am *ALWAYS* better off increasing compression rather than reducing
    resolution? Are there no exceptions to this rule? One would think that
    manufacturers would have latched on to this conclusion and provided just the
    one (the highest) resolution and say 9 compression steps, rather than three
    resolution and three compression steps.

    Regards - JW
    John Wright, Sep 8, 2004
    #7
  8. "John Wright" <> wrote in message
    news:413e3ddc$0$15471$...
    All digicams provide several resolution levels and compression levels.
    Using the highest resolution and the lowest compression produces maximum
    image file sizes. If you wanted to pack more photos into your card, you
    would have to reduce file sizes by either reducing resolution, by
    increasing compression, or both.

    When is increasing compression better than reducing resolution?

    And when is reducing resolution better than increasing compression?

    Regards - JW
    -------------------

    John,

    Carry out tests with typical subjects on your camera. I did this, and
    found that increasing compression was more acceptable than reducing
    resolution. Mind you, I think that Nikon has some of the best JPEG
    compression algorithm tuning that I have seen (compared to Minolta and
    Canon).

    Also, although I sometimes print, most of my work is displayed via CRT or
    LCD monitors so even though I crop, each displayed pixel is interpolated
    from a number of taking pixels, which will help reduce the effects of
    greater JPEG compression.

    Cheers,
    David
    David J Taylor, Sep 8, 2004
    #8
  9. John Wright

    grim Guest

    Always increase compression if you need smaller files. Only decrease
    resolution as a last resort. It's always better to use more jpeg
    compression, since it will result it less loss of detail than a smaller
    image resolution with the same file size.

    The only reason why you'd ever shoot low-resolution and low-compression is
    if you knew in advance your resolution had to be 640x480 because it has to
    fit on a web page or something. And even that presupposes you don't have any
    picture-editing software to do the shrinking later.


    "John Wright" <> wrote in message
    news:413e3ddc$0$15471$...
    All digicams provide several resolution levels and compression levels. Using
    the highest resolution and the lowest compression produces maximum image
    file sizes. If you wanted to pack more photos into your card, you would have
    to reduce file sizes by either reducing resolution, by increasing
    compression, or both.

    When is increasing compression better than reducing resolution?

    And when is reducing resolution better than increasing compression?

    Regards - JW
    grim, Sep 8, 2004
    #9
  10. John Wright

    bob Guest

    "John Wright" <> wrote in news:413e3ddc$0$15471
    $:

    > When is increasing compression better than reducing resolution?
    >


    Almost always. Someone did a series of experiments and posted the results
    on the web a year or two ago.

    I shoot low res sometimes. For instance, when I take pictures of objects
    for Ebay, or when I am documenting something, like taking a picture of a
    sign, instead of writing it down.

    As an aside, several people who have done tests with Nikon CP5000 cameras
    have found that, when evaluating the final prints, RAW and Fine .jpg are
    essentially indistinguishable. I like Larry's website http://www.larry-
    bolch.com/ for his essay on layering bracketed shots to extend dynamic
    range, and also on RAW mode.

    Bob

    --
    Delete the inverse SPAM to reply
    bob, Sep 8, 2004
    #10
  11. John Wright

    Guest

    Kibo informs me that bob <> stated that:

    >As an aside, several people who have done tests with Nikon CP5000 cameras
    >have found that, when evaluating the final prints, RAW and Fine .jpg are
    >essentially indistinguishable. I like Larry's website http://www.larry-
    >bolch.com/ for his essay on layering bracketed shots to extend dynamic
    >range, and also on RAW mode.


    *Fascinating* stuff on Larry's website, Bob. Thanks for posting the
    link. :)

    --
    W
    . | ,. w , "Some people are alive only because
    \|/ \|/ it is illegal to kill them." Perna condita delenda est
    ---^----^---------------------------------------------------------------
    , Sep 8, 2004
    #11
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