8 Replies Latest reply: Mar 3, 2016 10:37 PM by Terence Devlin
crabpaws Level 1 Level 1
expertise.macosx
Mac OS X

Hi -- I had a slide scanned to be printed (yes, printed) in a 10.8" x 14.4" size by a process that requires 300 ppi.

 

I imported the scanned jpeg into iPhoto at 1500 ppi, but I can't seem to be able to edit it and export it at anything but 72 ppi.

 

How can I export my photo with changes from iPhoto at 300 ppi?

 

I know this is an existential question, but why does this have to be so hard?

 

(No, I don't have Photoshop or Photoshop Elements.)


Mac mini, Mac OS X (10.6.8)
  • LarryHN Level 10 Level 10
    expertise.photosformac
    Photos for Mac

    DPI - Dots per inch) is meaningless until you actually print - while there is a DPI field in a digital photo it is meaningless - the DPI is determined by the pixel size of the photo and the print size - to print a 10.8 x 14.4 image at 300 dpi you need a digital photo that is 3240x4320 pixels - export as that size or larger and your print will be 300 DPI

     

    See  The Myth of DPI for additional information.

     

    LN

  • crabpaws Level 1 Level 1
    expertise.macosx
    Mac OS X

    Thank you for attempting an answer.

     

    I believe I mentioned this was for print (yes, print) and the process requires 300 ppi. No myth there.

     

    Prior to posting here, I'd already done as you suggested. The online print system still will not accept my file. When I look at it in Preview, it shows 72 ppi.

     

    So I followed your instructions, exporting from iPhoto at Custom size Max width 4320 pixels, and went through the process again. The result is the same. My image has been rejected, and it reads 72 ppi in Preview.

     

    Any other suggestions?

     

    (And why doesn't iPhoto show ppi as part of Info?)

  • Meg The Dog Level 6 Level 6
    expertise.video
    Video

    Export your photo to the desktop.

    Open your photo in the Preview.app.

    In Preview, go Tools > Adjust Size . . .

    PreviewScreenSnapz001.jpg

     

    Then set the DPI to 300:

     

    PreviewScreenSnapz002.jpg

     

    Click OK,

    And then Save the image.

     

    MtD

  • LarryHN Level 10 Level 10
    expertise.photosformac
    Photos for Mac
    Any other suggestions?

    Contact CS for the print vendor - they have a problem  - without a graphic editor (like Preview) or an EXIF editor you can not change the DPI setting

     

    (And why doesn't iPhoto show ppi as part of Info?)

     

    Because

     

    DPI - Dots per inch) is meaningless until you actually print - while there is a DPI field in a digital photo it is meaningless

    Digital photos files simpy do not have inches associated  with them - they only have dots (pixels) - no inches

     

    See  The Myth of DPI for additional information.

     

    LN

  • Sierra Sky Pilot Level 1 Level 1

    Thank you for this simple solution!  However, does anyone know, however, the conversion of pip (pixels per inch) to mb?  In my Photos app, info about photos is in mb, not pixels. For instance, a photo of a shrub blooming with flowers had this info:  Canon PowerShot SD630, 5.8-17.4mm, 2272 × 1704 444 KB, JPEG.  Mac Photo (or iPhoto either) don't show information about pixels. 

  • LarryHN Level 10 Level 10
    expertise.photosformac
    Photos for Mac

    It is true that you can do that and change the EXIF field entry - however that accomplishes nothing except to change a meaningless EXIF field - the DPI of a print is the answer to a third grade math problem - and nothing in the EXIF files has any effect of this - all you are accomplishing is reducing the quality of the photo by doing one additional totally unnecessary and meaningless PEG conversion - it is the same as writing BMW on the side of your Honda - it does not change anything except mess up the looks of the Honda

     

    LN

  • LarryHN Level 10 Level 10
    expertise.photosformac
    Photos for Mac

    Pixel dimensions are in the info window in Photos along with the other metadata from the camera - same is true of iPhoto

     

    Right click on one photo and get info - it is all there

     

    LN

  • Terence Devlin Level 10 Level 10
    expertise.ilife
    iLife
    For instance, a photo of a shrub blooming with flowers had this info:  Canon PowerShot SD630, 5.8-17.4mm, 2272 × 1704 444 KB, JPEG.

     

    The bit highlighted and underlined are the pixel dimensions of the photograph.

     

    There is no straightforward conversion rate between the pixel dimensions and the size of the file. It depends on the content of the file, the quality of the file and so on.