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A
arnoenzo17628449
Known Participant
November 4, 2021
Question

Which information is lost when saving .ai as hi-res pdf?

  • November 4, 2021
  • 2 replies
  • 687 views

I have a general question about the difference between .ai files and .pdf.

Example:
I have a 25Mb .ai file and I save it as a print-resolution .pdf. The pdf is appr. 10Mb.
When I read the pdf back into Illustrator, the file structure, layers, links and effects appear to be completely preserved. What is causing the difference in file size between .ai and .pdf, i.e. which information is omitted from the .ai file when saving to .pdf?
Why would I continue to save an .ai file, while I can save 15Mb for "the same file" in .pdf format?

    This topic has been closed for replies.

    2 replies

    John Mensinger
    John Mensinger
    Community Expert
    November 4, 2021

    None of this has any impactful meaning unless there is raster data in the file, but you haven't revealed whether there is. You do mention "resolution," but many posters here make erroneous references to that when speaking only of vector data, so I'd rather not assume.

     

    If there is indeed raster data in the file, then that's where the potential for "loss" occurs, depending on the resolution resident  prior to and following Save As PDF, subject to the resolution and compression settings in the Save PDF dialog.

    A
    arnoenzo17628449Author
    Known Participant
    November 4, 2021

    John, there are both photographs and vector objects in the file.
    Unless supplied with a .joboptions file from printers, we per default save our pdfs in the (modified with cropmarks, etc.) Press Quality preset.

    Ton Frederiks
    Ton Frederiks
    Community Expert
    November 4, 2021

    There is a lot of information lost when saving a PDF without checking the "Preserve Illustrator Editing Capabilities". To name a few: Brushes, Symbols, Appearances, Graphic Styles, Swatches, Layers.

    So only do this with a copy and close the file after saving.

      A
      arnoenzo17628449Author
      Known Participant
      November 4, 2021

      Thanks for your prompt response, Ton.
      I have "Preserve Illustrator Editing Capabilities" checked, so the difference in size comes from something else that is omitted.

      Doug A Roberts
      Doug A Roberts
      Community Expert
      November 4, 2021

      If you take your 25 MB AI file and Save As... then create a copy, is it still 25 MB?

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