Help! Need explanation of "X & Y resolution"

Discussion in 'Digital Photography' started by Ralph O'Rourke, Jul 15, 2003.

  1. Just got a new Pentax Optio S.

    Copied first round of photos to my computer software and checked the
    complete metadata.

    There were entries for X resolution = 72 and Y resolution = 72.

    Now the photo itself was taken at 2048 x 1536 pixels and at *** (best)
    compression.

    Compared to the above settings, 72 kinda seems low--whatever it
    means--especially since my old $50 1.3mp Concord shot X/Y at 96
    resolution.

    What DOES it mean, anyway?
     
    Ralph O'Rourke, Jul 15, 2003
    #1
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  2. Ralph O'Rourke

    Charlie Guest

    On Tue, 15 Jul 2003 02:28:36 GMT, Ralph O'Rourke
    <> wrote:

    >Just got a new Pentax Optio S.
    >
    >Copied first round of photos to my computer software and checked the
    >complete metadata.
    >
    >There were entries for X resolution = 72 and Y resolution = 72.
    >
    >Now the photo itself was taken at 2048 x 1536 pixels and at *** (best)
    >compression.
    >
    >Compared to the above settings, 72 kinda seems low--whatever it
    >means--especially since my old $50 1.3mp Concord shot X/Y at 96
    >resolution.
    >
    >What DOES it mean, anyway?


    Nothing. Ignore completely any dpi or ppi value unless you're talking
    about making a print. In the camera or in the computer the term is
    meaningless.

    The 2048 x 1536 is meaningful, as is the compression value used
    because they relate to how much real image data is in the picture.
    --
    Charlie Hoffpauir
    http://freepages.genealogy.rootsweb.com/~charlieh/
    If you really want to reply via email, my valid
    address is available on my web site.
     
    Charlie, Jul 15, 2003
    #2
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  3. Ralph O'Rourke

    Paul Cordes Guest

    "Ralph O'Rourke" <> wrote in message
    news:...
    > Just got a new Pentax Optio S.
    >
    > Copied first round of photos to my computer software and checked the
    > complete metadata.
    >
    > There were entries for X resolution = 72 and Y resolution = 72.
    >
    > Now the photo itself was taken at 2048 x 1536 pixels and at *** (best)
    > compression.
    >
    > Compared to the above settings, 72 kinda seems low--whatever it
    > means--especially since my old $50 1.3mp Concord shot X/Y at 96
    > resolution.
    >
    > What DOES it mean, anyway?


    72 dpi is the resolution of your monitor and since that's what your looking
    at the photo on that's what the "resolution" is.
    The pixels are pixels. Eventually you'll end up changing the "resolution"
    so that your printer will like the photo, usually anywhere from 220 to 330
    dpi.......and the pixels will still just be the pixels.

    Clear as mud?
     
    Paul Cordes, Jul 15, 2003
    #3
  4. Ralph O'Rourke

    Jim Townsend Guest

    Ralph O'Rourke wrote:

    > Just got a new Pentax Optio S.
    >
    > Copied first round of photos to my computer software and checked the
    > complete metadata.
    >
    > There were entries for X resolution = 72 and Y resolution = 72.
    >
    > Now the photo itself was taken at 2048 x 1536 pixels and at *** (best)
    > compression.
    >
    > Compared to the above settings, 72 kinda seems low--whatever it
    > means--especially since my old $50 1.3mp Concord shot X/Y at 96
    > resolution.
    >
    > What DOES it mean, anyway?


    Check whatever imaging editing software you are using.. You'll see that the X
    and Y resolution are in pixels per inch (or sometimes dots per inch) PPI and
    DPI are often used interchangeably.

    In this window you will have both 'pixels per inch' AND size in inches. The
    resolution you are asking about shows the size the image will be when it is
    printed on paper. It has nothing to do with the resolution of the digital
    image your camera just produced.

    Pixels per inch are incredibly easy to understand.

    If you take a 1000 pixel wide image and print it on paper and make it 10 inches
    wide.. you just spread 1000 pixels evenly across 10 inches of paper. If you
    want to know how many pixels there are in just one inch, of this 10 inch
    picture simply divide..

    1000 pixels divided by 10 inches = 100 Pixels per inch. (That wasn't hard was
    it :)

    Now back to your 2048 x 1536 image. You'll see it shows a size of 28.44 inches
    by 21.33 inches. Again.. Those inches are the size your image will be if you
    try print it on paper.

    The math is shown below:

    2048 pixels divided by 72 pixels per inch = 28.44 inches
    1536 pixels divided by 72 pixels per inch = 21.33 inches

    You should also notice you can change this value of 72 to anything you want.
    If you don't like 72.. well, then change it to 300... If you do change it to
    300, the you'll see the image size in inches changes as well.. It will change
    to:

    2048 pixels divided by 300 pixels per inch = 6.82 inches
    1536 pixels divided by 300 pixels per inch = 5.12 inches

    So you see, this resolution is ONLY for printing on paper. It's simply the
    total pixels divided by the desired print size. 72 is a common default
    resolution. It's there because someone thought it would be nice. It has no
    effect on your image.

    All you change when you change this 'resolution' is a couple of bytes in the
    image header. All the other bytes, pixels and everything else remains the
    same. These couple of bytes in the image header are read by your printer
    software and determine how big the image will be when it is printed on paper.
     
    Jim Townsend, Jul 15, 2003
    #4
  5. Thank you for your explanation.

    My concern is NOT display resolution--I could care less about that.
    My concern is PRINT resolution.

    My software = Adobe Photoshop Elements2.0 and THIS is where the X/Y
    resolution shows as in the metadata. Within the same software, the
    photo next to it--taken with a $50 Concord--shows as 96 resolution.

    I just want to make sure I'm gonna be able to aprint at 300dpi, and I
    cannot see any additional settings on the cmera (other that # of
    pixels, and the amount of compression.

    Do you happen to know offhand, where I set the 300dpi specification
    for printing in Elements?

    Thx,
    RR

    |||||Ralph O'Rourke wrote:
    |||||
    |||||> Just got a new Pentax Optio S.
    |||||>
    |||||> Copied first round of photos to my computer software and checked the
    |||||> complete metadata.
    |||||>
    |||||> There were entries for X resolution = 72 and Y resolution = 72.
    |||||>
    |||||> Now the photo itself was taken at 2048 x 1536 pixels and at *** (best)
    |||||> compression.
    |||||>
    |||||> Compared to the above settings, 72 kinda seems low--whatever it
    |||||> means--especially since my old $50 1.3mp Concord shot X/Y at 96
    |||||> resolution.
    |||||>
    |||||> What DOES it mean, anyway?
    |||||
    |||||Check whatever imaging editing software you are using.. You'll see that the X
    |||||and Y resolution are in pixels per inch (or sometimes dots per inch) PPI and
    |||||DPI are often used interchangeably.
    |||||
    |||||In this window you will have both 'pixels per inch' AND size in inches. The
    |||||resolution you are asking about shows the size the image will be when it is
    |||||printed on paper. It has nothing to do with the resolution of the digital
    |||||image your camera just produced.
    |||||
    |||||Pixels per inch are incredibly easy to understand.
    |||||If you take a 1000 pixel wide image and print it on paper and make it 10 inches
    |||||wide.. you just spread 1000 pixels evenly across 10 inches of paper. If you
    |||||want to know how many pixels there are in just one inch, of this 10 inch
    |||||picture simply divide..
    |||||
    |||||1000 pixels divided by 10 inches = 100 Pixels per inch. (That wasn't hard was
    |||||it :)
    |||||
    |||||Now back to your 2048 x 1536 image. You'll see it shows a size of 28.44 inches
    |||||by 21.33 inches. Again.. Those inches are the size your image will be if you
    |||||try print it on paper.
    |||||
    |||||The math is shown below:
    |||||
    |||||2048 pixels divided by 72 pixels per inch = 28.44 inches
    |||||1536 pixels divided by 72 pixels per inch = 21.33 inches
    |||||
    |||||You should also notice you can change this value of 72 to anything you want.
    |||||If you don't like 72.. well, then change it to 300... If you do change it to
    |||||300, the you'll see the image size in inches changes as well.. It will change
    |||||to:
    |||||
    |||||2048 pixels divided by 300 pixels per inch = 6.82 inches
    |||||1536 pixels divided by 300 pixels per inch = 5.12 inches
    |||||
    |||||So you see, this resolution is ONLY for printing on paper. It's simply the
    |||||total pixels divided by the desired print size. 72 is a common default
    |||||resolution. It's there because someone thought it would be nice. It has no
    |||||effect on your image.
    |||||
    |||||All you change when you change this 'resolution' is a couple of bytes in the
    |||||image header. All the other bytes, pixels and everything else remains the
    |||||same. These couple of bytes in the image header are read by your printer
    |||||software and determine how big the image will be when it is printed on paper.
    |||||
     
    Ralph O'Rourke, Jul 15, 2003
    #5
  6. Jim: CORRECTION TO THE BELOW.
    PRINT SOFTWARE = ADOBE PHOTOSHOP ALBUM, NOT ELEMENTS

    Thank you for your explanation.

    My concern is NOT display resolution--I could care less about that.
    My concern is PRINT resolution.

    My software = Adobe Photoshop Elements2.0 and THIS is where the X/Y
    resolution shows as in the metadata. Within the same software, the
    photo next to it--taken with a $50 Concord--shows as 96 resolution.

    I just want to make sure I'm gonna be able to aprint at 300dpi, and I
    cannot see any additional settings on the cmera (other that # of
    pixels, and the amount of compression.

    Do you happen to know offhand, where I set the 300dpi specification
    for printing in Elements?

    Thx,
    RR

    |||||Ralph O'Rourke wrote:
    |||||
    |||||> Just got a new Pentax Optio S.
    |||||>
    |||||> Copied first round of photos to my computer software and checked the
    |||||> complete metadata.
    |||||>
    |||||> There were entries for X resolution = 72 and Y resolution = 72.
    |||||>
    |||||> Now the photo itself was taken at 2048 x 1536 pixels and at *** (best)
    |||||> compression.
    |||||>
    |||||> Compared to the above settings, 72 kinda seems low--whatever it
    |||||> means--especially since my old $50 1.3mp Concord shot X/Y at 96
    |||||> resolution.
    |||||>
    |||||> What DOES it mean, anyway?
    |||||
    |||||Check whatever imaging editing software you are using.. You'll see that the X
    |||||and Y resolution are in pixels per inch (or sometimes dots per inch) PPI and
    |||||DPI are often used interchangeably.
    |||||
    |||||In this window you will have both 'pixels per inch' AND size in inches. The
    |||||resolution you are asking about shows the size the image will be when it is
    |||||printed on paper. It has nothing to do with the resolution of the digital
    |||||image your camera just produced.
    |||||
    |||||Pixels per inch are incredibly easy to understand.
    |||||If you take a 1000 pixel wide image and print it on paper and make it 10 inches
    |||||wide.. you just spread 1000 pixels evenly across 10 inches of paper. If you
    |||||want to know how many pixels there are in just one inch, of this 10 inch
    |||||picture simply divide..
    |||||
    |||||1000 pixels divided by 10 inches = 100 Pixels per inch. (That wasn't hard was
    |||||it :)
    |||||
    |||||Now back to your 2048 x 1536 image. You'll see it shows a size of 28.44 inches
    |||||by 21.33 inches. Again.. Those inches are the size your image will be if you
    |||||try print it on paper.
    |||||
    |||||The math is shown below:
    |||||
    |||||2048 pixels divided by 72 pixels per inch = 28.44 inches
    |||||1536 pixels divided by 72 pixels per inch = 21.33 inches
    |||||
    |||||You should also notice you can change this value of 72 to anything you want.
    |||||If you don't like 72.. well, then change it to 300... If you do change it to
    |||||300, the you'll see the image size in inches changes as well.. It will change
    |||||to:
    |||||
    |||||2048 pixels divided by 300 pixels per inch = 6.82 inches
    |||||1536 pixels divided by 300 pixels per inch = 5.12 inches
    |||||
    |||||So you see, this resolution is ONLY for printing on paper. It's simply the
    |||||total pixels divided by the desired print size. 72 is a common default
    |||||resolution. It's there because someone thought it would be nice. It has no
    |||||effect on your image.
    |||||
    |||||All you change when you change this 'resolution' is a couple of bytes in the
    |||||image header. All the other bytes, pixels and everything else remains the
    |||||same. These couple of bytes in the image header are read by your printer
    |||||software and determine how big the image will be when it is printed on paper.
    |||||
     
    Ralph O'Rourke, Jul 15, 2003
    #6
  7. Ralph O'Rourke

    Paul Cordes Guest

    "Ralph O'Rourke" <> wrote in message
    news:p...
    > Thank you for your explanation.
    >
    > My concern is NOT display resolution--I could care less about that.
    > My concern is PRINT resolution.
    >
    > My software = Adobe Photoshop Elements2.0 and THIS is where the X/Y
    > resolution shows as in the metadata. Within the same software, the
    > photo next to it--taken with a $50 Concord--shows as 96 resolution.
    >
    > I just want to make sure I'm gonna be able to aprint at 300dpi, and I
    > cannot see any additional settings on the cmera (other that # of
    > pixels, and the amount of compression.
    >
    > Do you happen to know offhand, where I set the 300dpi specification
    > for printing in Elements?
    >
    > Thx,
    > RR


    You have the picture on the screen in Elements.
    Now, Image> Resize> Image Size.
    Take the checkmark in the Resample box (lower left) and remove it.
    Now pick a size for one of the dimensions of the print, like the heigth of 4
    for a 4X6.
    You'll see the dpi change to the right amount for that print size. If you
    want to print larger than 4X6 you may want to have the resample box checked
    and make sure that the picture gets to 300dpi......but that's a whole nother
    discussion.

    Now, print away!
     
    Paul Cordes, Jul 15, 2003
    #7
  8. Ralph O'Rourke

    Paul Cordes Guest

    "Ralph O'Rourke" <> wrote in message
    news:...
    > Paul:
    > Thank you for responding.
    >
    > Are you familiar with Adobe Photoshop Album? If so, can you tell me
    > where I specify 200/300dpi for printing in Album? I can only find
    > inches and centimeters.
    >
    > RR


    Don't have Album.
    But in general you just specify the inches that you want and let the dpi
    fall where it may. Your Pentax will be good for all print sizes up to 8X10
    without worrying about the dpi. If you want to print posters then you'll
    have to get into the proper dpi and how to get it from the amount of pixels
    you have to work with.

    As an aside if you specify 4 inches for one dimension you notice that the
    other is 5.3 inches. Not the 4X6 you had in mind. That's because the
    camera is not in the same ratio as 4X6. So you'll want to crop to that
    ratio first. Ditto 5X7 and 8X10. They're all different ratios than the one
    the camera comes in.

    Clear as mud?
     
    Paul Cordes, Jul 15, 2003
    #8
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