printing resolution

Discussion in 'Digital Photography' started by ivan danicic, Nov 1, 2004.

  1. ivan danicic

    ivan danicic Guest

    Hello All, I open a picture in psp7 and click on 'image info'.
    It displays :
    Image: dimension 3072x2048 pixels.
    6.000x4.000 inches.
    pixels per inch 512.

    Where does this information come from? I know about the dimension but not
    about 6x4 (or equivalently 512).
    I have not asked the program for any resolution so far.
    Any comments gratefully received.
    Ivan
     
    ivan danicic, Nov 1, 2004
    #1
    1. Advertising

  2. ivan danicic

    Fred Hiltz Guest

    ivan danicic wrote:
    > Hello All, I open a picture in psp7 and click on 'image info'.
    > It displays :
    > Image: dimension 3072x2048 pixels.
    > 6.000x4.000 inches.
    > pixels per inch 512.
    >
    > Where does this information come from? I know about the dimension
    > but not about 6x4 (or equivalently 512). I have not asked the
    > program for any resolution so far.


    Hi Ivan. Some file formats carry the resolution set by whatever app
    wrote the file, but many do not. If the file does not say, PSP uses
    the default resolution that you set with File Preferences > General
    Program Preferences > Rulers and Units.
    --
    Fred Hiltz, fhiltz at yahoo dot com
     
    Fred Hiltz, Nov 1, 2004
    #2
    1. Advertising

  3. Wasn't it ivan danicic who wrote:
    >Hello All, I open a picture in psp7 and click on 'image info'.
    >It displays :
    >Image: dimension 3072x2048 pixels.
    > 6.000x4.000 inches.
    > pixels per inch 512.
    >
    >Where does this information come from? I know about the dimension but not
    >about 6x4 (or equivalently 512).
    >I have not asked the program for any resolution so far.


    PSP7 always considers an image to have a physical print size as well as
    a dimension in pixels. It's not used very much except when you print the
    image and don't specify anything that overrides it.

    When you create a new image, you enter the resolution and can either
    enter the dimension in pixels or the print size in inches or
    centimetres. So if you ask PSP7 to create an image that is 3072x2048
    pixels and has a resolution of 512 pixels/inch then it will calculate
    the print size in inches for you.

    Some image file formats store the print resolution, and PSP7 will read
    the value when it opens an existing image.

    Some image formats don't have the ability to store the resolution. When
    PSP7 loads such an image it will use the default resolution.

    You can change the default resolution under File => Preferences =>
    General Preferences => Rulers and Units.

    You can change the print size/resolution of an image without changing
    its dimension with Image => Resize by selecting the "Actual/Print Size"
    button.

    --
    Mike Williams
    Gentleman of Leisure
     
    Mike Williams, Nov 1, 2004
    #3
  4. ivan danicic

    Alan Meyer Guest

    "ivan danicic" <> wrote in message
    news:h0qhd.27845$...
    > Hello All, I open a picture in psp7 and click on 'image info'.
    > It displays :
    > Image: dimension 3072x2048 pixels.
    > 6.000x4.000 inches.
    > pixels per inch 512.
    >
    > Where does this information come from? I know about the dimension but not
    > about 6x4 (or equivalently 512).
    > I have not asked the program for any resolution so far.
    > Any comments gratefully received.
    > Ivan


    Dimensions come from the physical properties of the image
    file. Every file has data in it representing so many pixels high
    and so many wide. It is a fixed property of the image unless
    you crop, resize or resample it.

    "pixels per inch" is an indication from some software in the
    camera, scanner, or photo editor to some other software, usually
    in a printer driver, telling it how big to print this image. 512
    pixels per inch is a very high number. Very high quality prints
    are possible at 200-300 ppi. The number is a suggestion.
    Your printer software should be able to print the image at
    any size you tell it to, regardless of that number - though
    in the absence of any other instructions your printer software
    might use this suggestion. This number too is stored in the file.

    "6.000 x 4.000 inches" is just (3072/512) x (2048/512).
    It may not be stored in the file, just computed.

    Alan
     
    Alan Meyer, Nov 1, 2004
    #4
  5. ivan danicic

    ivan danicic Guest

    Hello, As I said, I know about the dimension of the scanned image, 3072x2048
    pixels, but I want to know what theoretical basis there is for the printing
    resolution, here 512 ppi. At this stage I would have thought that PSP knows
    nothing about what printer will be used, yet there is the suggestion that by
    printing at a different resolution something will be lost. Kindly explain.
    Ivan.
    "Mike Williams" <> wrote in message
    news:...
    > Wasn't it ivan danicic who wrote:
    >>Hello All, I open a picture in psp7 and click on 'image info'.
    >>It displays :
    >>Image: dimension 3072x2048 pixels.
    >> 6.000x4.000 inches.
    >> pixels per inch 512.
    >>
    >>Where does this information come from? I know about the dimension but not
    >>about 6x4 (or equivalently 512).
    >>I have not asked the program for any resolution so far.

    >
    > PSP7 always considers an image to have a physical print size as well as
    > a dimension in pixels. It's not used very much except when you print the
    > image and don't specify anything that overrides it.
    >
    > When you create a new image, you enter the resolution and can either
    > enter the dimension in pixels or the print size in inches or
    > centimetres. So if you ask PSP7 to create an image that is 3072x2048
    > pixels and has a resolution of 512 pixels/inch then it will calculate
    > the print size in inches for you.
    >
    > Some image file formats store the print resolution, and PSP7 will read
    > the value when it opens an existing image.
    >
    > Some image formats don't have the ability to store the resolution. When
    > PSP7 loads such an image it will use the default resolution.
    >
    > You can change the default resolution under File => Preferences =>
    > General Preferences => Rulers and Units.
    >
    > You can change the print size/resolution of an image without changing
    > its dimension with Image => Resize by selecting the "Actual/Print Size"
    > button.
    >
    > --
    > Mike Williams
    > Gentleman of Leisure
     
    ivan danicic, Nov 1, 2004
    #5
  6. ivan danicic

    Trev Guest

    "ivan danicic" <> wrote in message
    news:eek:Ruhd.1681$...
    > Hello, As I said, I know about the dimension of the scanned image,
    > 3072x2048 pixels, but I want to know what theoretical basis there is for
    > the printing resolution, here 512 ppi. At this stage I would have thought
    > that PSP knows nothing about what printer will be used, yet there is the
    > suggestion that by printing at a different resolution something will be
    > lost. Kindly explain.
    > Ivan.


    Divide 3072 pixels by 512 pixels to an inch and you get 6 inch. There is no
    change in the image resolution. The printer needs to know how you wish to
    pack the pixels together to get a finished size on paper. Of course if you
    changed the ppi to 307 you would get a 10 inch wide print
     
    Trev, Nov 1, 2004
    #6
  7. Wasn't it ivan danicic who wrote:
    >Hello, As I said, I know about the dimension of the scanned image, 3072x2048
    >pixels, but I want to know what theoretical basis there is for the printing
    >resolution, here 512 ppi. At this stage I would have thought that PSP knows
    >nothing about what printer will be used, yet there is the suggestion that by
    >printing at a different resolution something will be lost. Kindly explain.


    If you've scanned the image, then it might make sense for you to use
    Image->Resize and use "Actual/Print Size" to set the resolution to that
    with which you scanned your image, rather then leaving it at the default
    resolution. Then the print size will match the size of your original
    source.

    It's really up to you what resolution you want PSP to use. PSP7 simply
    tells the printer what you told it (or it picked up from the default
    that you configured). The PIXELS per inch that PSP tells the printer to
    print bears no relationship to the DOTS per inch capability of the
    printer. In some cases that loses some of the detail that you scanned,
    but then you could say that's because you used too high a resolution
    when you scanned it.

    --
    Mike Williams
    Gentleman of Leisure
     
    Mike Williams, Nov 1, 2004
    #7
  8. ivan danicic

    Alan Meyer Guest

    "ivan danicic" <> wrote in message
    news:eek:Ruhd.1681$...
    > Hello, As I said, I know about the dimension of the scanned image,

    3072x2048
    > pixels, but I want to know what theoretical basis there is for the

    printing
    > resolution, here 512 ppi. At this stage I would have thought that PSP

    knows
    > nothing about what printer will be used,


    Correct. This is not a command to a specific printer. PSP does not
    know what printer you might use. It is a generic suggestion to any printer
    to assume that 512 pixels = 1 inch.

    > yet there is the suggestion that by
    > printing at a different resolution something will be lost. Kindly explain.


    What the PSP suggestion is doing is telling the printer that the
    author of this image intended to get a 6x4 inch print - in the
    absence of any other directives from the guy making the print,
    produce a 6x4 inch print for him.

    If anything, information will be lost if you print at 6x4 because the
    printer
    won't be able to actually reproduce 512 pixels per inch and so the driver
    will "downsample" the image to its maximum resolution which might
    only be 150 ppi, or thereabouts. It will average 3-4 pixels in each
    dimension, converting 9-16 (width x height) pixels to a single point
    on the page. Understanding dots per inch vs. pixels per inch is also
    complicated, but that's another story.

    As somebody else pointed out, you may have a setting somewhere
    in your PSP configuration defaults that tells it assume everything
    will be printed at 6x4 and calculate pixels per inch according, or
    to assume everything will be printed at 512 ppi and calculate inches
    accordingly. It's probably not something you set, but something
    that PSP set for you by default.

    You may also see some on screen image viewers respecting this
    number - downsampling the image to display it at around 6x4
    inches, even though the actual display resolution is only somewhere
    between 60 and 100 pixels per inch and pixels must be thrown
    away (or averaged away) to get the image that small.

    Alan
     
    Alan Meyer, Nov 1, 2004
    #8
  9. ivan danicic

    ivan danicic Guest

    Alan Meyer wrote:

    > "ivan danicic" <> wrote in message
    > news:h0qhd.27845$...
    >> Hello All, I open a picture in psp7 and click on 'image info'.
    >> It displays :
    >> Image: dimension 3072x2048 pixels.
    >> 6.000x4.000 inches.
    >> pixels per inch 512.
    >>
    >> Where does this information come from? I know about the dimension but not
    >> about 6x4 (or equivalently 512).
    >> I have not asked the program for any resolution so far.
    >> Any comments gratefully received.
    >> Ivan

    >
    >>

    snip
    > "6.000 x 4.000 inches" is just (3072/512) x (2048/512).
    > It may not be stored in the file, just computed.
    >
    > Alan

    Hello! I have only just installed psp so have had no opportunity to
    influence it in any way. OK; I get from all you kind people said that the
    512 ppi has no particular significance. If I want best quality rather than
    size of print, what should I do, knowing the size of the scanned image and
    the possible dots per inch of which my printer (epson 860) is capable?
    Thanks in advance.
    Ivan.
     
    ivan danicic, Nov 1, 2004
    #9
  10. ivan danicic

    Jim Guest

    "ivan danicic" <> wrote in message
    news:dwwhd.2907$...
    > Alan Meyer wrote:
    >
    > Hello! I have only just installed psp so have had no opportunity to
    > influence it in any way. OK; I get from all you kind people said that the
    > 512 ppi has no particular significance. If I want best quality rather than
    > size of print, what should I do, knowing the size of the scanned image and
    > the possible dots per inch of which my printer (epson 860) is capable?
    > Thanks in advance.
    > Ivan.

    240 pixels per inch. It is hard to see the difference between 200 and 300
    pixels per inch.
    1440 dots per inch. I can't see any difference between 1400 and 2880.
    Jim
     
    Jim, Nov 1, 2004
    #10
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. Jack Yeazel

    ISO Resolution Chart and Printing Resolution

    Jack Yeazel, Aug 12, 2003, in forum: Digital Photography
    Replies:
    0
    Views:
    3,314
    Jack Yeazel
    Aug 12, 2003
  2. hassy_user
    Replies:
    11
    Views:
    790
    Bart van der Wolf
    Oct 27, 2004
  3. elie
    Replies:
    0
    Views:
    976
  4. elie
    Replies:
    0
    Views:
    896
  5. elie
    Replies:
    0
    Views:
    937
Loading...

Share This Page