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Compression vs. Resolution (Pentax Optio S) - Photography

If you buy a 3 MP camera you may as well use all 3 MP. For web or e-mail display it probably doesn't make any difference which way you go because you wioll have to reduce the number of pixels you use so severly, anyway. For Printing, you would probably do better with 2048 X 1536 at maximum compression. More Pixels is usually better. However, I suspect that when you see how good a print you can make at 2048 x 1536 with lowest compression, you will print a lot more than you think you will right now. Memory cards ...

  1. #1

    Default Re: Compression vs. Resolution (Pentax Optio S)

    If you buy a 3 MP camera you may as well use all 3 MP.
    For web or e-mail display it probably doesn't make any difference which
    way you go because you wioll have to reduce the number of pixels you use
    so severly, anyway.
    For Printing, you would probably do better with 2048 X 1536 at maximum
    compression. More Pixels is usually better.
    However, I suspect that when you see how good a print you can make at
    2048 x 1536 with lowest compression, you will print a lot more than you
    think you will right now.
    Memory cards are so reasonably priced, nowadays that I'd just put in a
    128 MB card and save at lowest compression.
    Time between shots may be alittle longer, but how often do you need to
    shoot pictures at high sequential speed.
    If you REALLY need high sequential speed, then accept higher compresion,
    but don't make high compression your default choice. Just my opinion.
    Bob Williams

    "William M. Miller" wrote:
     

    Robert Guest

  2. #2

    Default Re: Compression vs. Resolution (Pentax Optio S)


    "William M. Miller" <std.com> wrote in message
    news:bfc5dk$d89fo$news.uni-berlin.de... 

    The size of a digital image is X by Y pixels. The unit for file size is
    bytes, usuall expressed as Kb or Mb.
     

    Compression doesn't change the number of pixels, but it can cause other
    image defects. The greater the compression, the more chance that these
    defects will show up, but the less the ocmpression the bigger the file
    size - and the smaller the number of files that will fit in a memory card. 
     

    A good test is to look at an area of slightly changing colors, like a
    cloudless sky. With too much compression you'lll see banding. 

    This refers to resizing the image - changing the number of pixels in the
    width and height. A good image editor should let you choose the compression
    algorithm; if you don't like the result, undo it and try another algorithm.
    I use Paint Shop Pro. If it is done in the camera, you don't have that
    control. I always take photos at the largest number of pictures that my
    camera allows, unless I'm on a long trip and am running out of memory cards.
     

    Take a series of test shots with different image sizes and compresssions.
    Compare them critically. Then decide what you want to use most of the time.
    For the occasional critical picture, you can reset the camera for maximum
    number of pixels and minimum compression, or even use an uncompressed
    format, such as TIFF.

    Always save the files directly from the camera, without any change. Storage
    on a CD is the most cost-effective. Blank CDs cost a few cents on sale, and
    can store hundreds of image files, and if your computer only has a CD-R
    drive, you can replace it with a CD-R/W drive at low cost. When you edit a
    picture and have to save it, do not overwrite the original file, but save
    the altered file with a new name or in a different folder. That way, you
    can always go back to the original file.
     


    Marvin Guest

  3. #3

    Default Re: Compression vs. Resolution (Pentax Optio S)



    "William M. Miller" wrote:
     

    Higher resolution with higher compression is better(for a
    given file size), as long as the compression is not extreme.
     

    JK Guest

  4. #4

    Default Re: Compression vs. Resolution (Pentax Optio S)

    The only reason you would take photos in the higher resolution is to print
    them. It doesn't make any difference for viewing in the computer screen.
    That's why you didn't notice a difference.

    Compression could make a difference in what you notice on the computer
    screen, if you compress a lot. Most of the time probably noticeable either.

    For printing snapshot size you wouldn't need the largest resolution either.
    It can help for large size prints.

    The thing is, even if you won't print most, you might occasionally want to
    print one, even make an enlargement. So, with storage and memory cheap these
    days, you could take the photos at a higher resolution, save them to CDs at
    that resolution, but would need to shrink them if you are going to e-mail
    them or put them on the web.

    Experiment some when you get the camera, and see how the results are with
    different settings, both on the computer screen and printed at different
    sizes. Of course it also depends on how large a memory card you get (Sandisk
    256 MB SD cards are now selling for less than $70 at many places), and how
    long you will go (if you're on a trip, for example) without being able to
    transfer them to computer, etc.



    "William M. Miller" <std.com> wrote in message
    news:bfc5dk$d89fo$news.uni-berlin.de... 


    MS Guest

  5. #5

    Default Re: Compression vs. Resolution (Pentax Optio S)

    In message <supernews.com>,
    "Marvin Margoshes" <net> wrote:
     

    Do you mean "tiling"? I've never seen banding in a JPEG due to
    compression. I see the 8*8 tiles, and how the edges of the tiles have
    more contrast than the information within the them.
    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <komm> 
    JPS@no.komm Guest

  6. #6

    Default Re: Compression vs. Resolution (Pentax Optio S)

    In message <nethere.net>,
    " MS" <com> wrote:
     

    The in-camera downsizing is actually better in many cases than what most
    viewing programs use for on-screen downsizing. Most viewing programs
    still seem to assume 486 computers that would take over a minute to do a
    decent downsizing with real resampling. Irfanview is one that does a
    half-way decent job, but only in full-screen mode, and only if you
    enable the option in the preferences.
    --

    <>>< ><<> ><<> <>>< ><<> <>>< <>>< ><<>
    John P Sheehy <komm> 
    JPS@no.komm Guest

  7. #7

    Default Re: Compression vs. Resolution (Pentax Optio S)


    <komm> wrote in message
    news:com... 
    >
    > Do you mean "tiling"? I've never seen banding in a JPEG due to
    > compression. I see the 8*8 tiles, and how the edges of the tiles have
    > more contrast than the information within the them.
    > --[/ref]
    Too much jpg compression reduces the number of colors in the image. Thus,
    the colors change less gradually, with distinct boundaries. You can get the
    same effect by reducing the monitor's number of colors. *The shape of each
    color region can be irregular. An 8X8 square would be unusual.


    Marvin Guest

  8. #8

    Default Re: Compression vs. Resolution (Pentax Optio S)

    William M. Miller wrote:
     

    For a given file size, more compression and more resolution
    generally beats less compression and lower resolution.

    See

    http://www.wfu.edu/~matthews/misc/graphics/ResVsComp/JpgResVsComp.html

    Rick Matthews

    matthews Guest

  9. #9

    Default Re: Compression vs. Resolution (Pentax Optio S)

    "matthews" <edu> wrote in message
    news:bfmt38$msu$spenet.wfu.edu... 
    >
    > For a given file size, more compression and more resolution
    > generally beats less compression and lower resolution.
    >
    > See
    >
    > http://www.wfu.edu/~matthews/misc/graphics/ResVsComp/JpgResVsComp.html[/ref]

    Thanks! That was a very helpful ysis.

    -- William M. Miller


    William Guest

  10. #10

    Default Re: Compression vs. Resolution (Pentax Optio S)

    matthews <edu> wrote in message news:<bfmt38$msu$spenet.wfu.edu>... 
    >
    > For a given file size, more compression and more resolution
    > generally beats less compression and lower resolution.
    >
    > See
    >
    > http://www.wfu.edu/~matthews/misc/graphics/ResVsComp/JpgResVsComp.html[/ref]

    Just a couple of comments:

    1. At extreme compression levels where blocking artifacts are clearly
    evident, the lower resolution scheme is generally preferable. This is
    the approach that JPEG 2000 takes, and it outperforms JPEG quite a bit
    at high compression ratios.

    2. JPEG is generally visually/perceptually lossless at about 20:1,
    when printed at 300 dpi on normal photoprocessed prints. Even at the
    highest compression setting on the optio s, the compression is less
    than this. In other words, even at the worst quality setting the
    artifacts you will see in print are due to the camera and not the
    compression. The caveat is that on monitor you will see artifacts
    more readily. However, most people are unlikely to view images at
    full res on screen simply because they won't fit; the downsampling
    process is likely to mitigate some of the effects of compression
    artifacts.

    3. I just purchased the optio s and I love everything about
    it....except the image quality: too much noise on indoor shots. The
    noise combined with the Bayer filter array interpolation causes a lot
    of ugly noise. But I'm probably more sensitive to this kind of thing
    because I used to evaluate image quality for a living....
    Troy Guest

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