Resolution vs. size vs. quality question

Discussion in 'Digital Photography' started by Destroy, Oct 27, 2003.

  1. Destroy

    Destroy Guest

    I'm kind of confused about quality digital pics.

    Say for example I have 2 cameras. Both exactly the same except one is
    2MP vs 5MP.

    Now say I take one pic with each camera at 640x480 res.

    Will both pics have the same quality? Why or why not?

    In a similar vein, say I want a smaller size pic.

    Using one camera, would one achieve better pic results by taking a
    1600x1200 pic within the camera and reducing it later with a editor or
    simply by taking the pic in 640x480 to begin with and using its original

    Destroy, Oct 27, 2003
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  2. Destroy

    JackD Guest

    If they are exactly the same the result would be exactly the same, however,
    since they are different they will be different for a number of reasons.

    Whether a reduced pic is done best in the camera or in the editor depends on
    the software implementation. In either case, if you are looking for 640x480
    either camera is sufficient. The biggest advantage of doing it in camera is
    that the file size is lower so you can store more pics. The biggest
    advantage of doing it afterwards is that you have the original file with
    higher resolution in case you decide that 640x480 is not enough.

    JackD, Oct 28, 2003
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  3. Quality is different than resolution. While each camera may have captured
    the same amount of information the quality of the information may be very
    different. This is due to the design of the camera hardware. The ability to
    capture detail in highlights and shadows, the color temperature and accuracy
    all have a significant role in image quality regardless of the image size.
    There is little if any image quality loss when downsampling an image. The
    advantage of a larger image is that you can make larger prints. I scan my
    film at the highest machine resolution possible and downsample for sizes
    less than the largest.
    Joe Thibodeau, Oct 28, 2003
  4. Destroy

    Mark Herring Guest

    Most digicams use the Bayer filter pattern in which color resolution
    is lower that luminance resolution. (and the colors are not spatially
    registered.) Thus, 5Mp downsampled to 640x480 will likely be hugely
    better than a native 640x480 camera (Can one even buy such a boat
    anchor anymore?)

    Personal habit: memory is cheap---I always take all pix (or scans) at
    the maximum resolution available. I can always downsample later in
    the computer, and who knows when you might want a blow up of some
    unique shot.


    digital photos, more and better computers,
    and never enough time to do the projects.
    Private e-mail: Just say no to No
    Mark Herring, Oct 28, 2003
  5. Destroy

    Don Stauffer Guest

    It may depend on the software. In each case the cameras are doing
    downsampling. It is possible with really good software that the camera
    with more pixels MAY do a better job of downsampling, but that is not
    assured entirely by number of pixels.

    While the number of pixels is the prime factor in quality (actual
    resolution vs just number of pixels), there ARE other factors that
    influence actual resolution.

    By ACTUAL resolution I mean it in the sense in which it is used in film
    photography, the number of alternating black and white lines actually
    visible in a capture image of a bar chart.
    Don Stauffer, Oct 28, 2003
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