Can anyone help with a pdf question?

[tmiller_iluvprinting]

I have noticed a fairly large size difference between pdf's exported out of Illustrator CS v5.1 and pdf's exported out of InDesign CS v5.5. The pdf's exported out of Illustrator are almost twice as large as the pdf's out of InDesign, and there are some noticeable quality differences. The document and image sizes are exact, and the pdf's are exported using the same exact settings in both programs?
Best regards,
Todd

 

[WharfRat]

You are probably saving the "Illustrator" file inside of the PDF.
-
When one saves a PDF file, the current (i.e. 12) and recent versions of Illustrator do save Illustrator documents
inside a PDF file, BUT in fact, the Illustrator editable information is saved as private data in the PDF file. In saving an
Illustrator document, you do have the option of creating a file with true PDF data, in which case you can actually open
up the .AI file in Acrobat or Reader. Conversely, there is an option in saving PDF files from Illustrator that allows you
to save the Illustrator edit information in which case you can fully and properly open the .PDF file in Illustrator.
In the general case, if a PDF file is not created by the same or earlier version of Illustrator and does not have the
“private data” describing the document, opening a PDF file in Adobe Illustrator results in a potentially lossy
operation. Adobe Illustrator does not support all features and options of PDF. Mixed colorspaces and other
features not supported by Illustrator will result in data and/or features from the PDF being discarded without
specific notice to the user.
A comparable situation exists with regards to both EPS (Encapsulated PostScript) and PostScript files.
In the case of EPS, Adobe Illustrator can only fully and properly edit EPS files created by the current or
earlier versions of Illustrator. (dov)

MSD

 

[Lukas Engqvist]

An Illustrator file normally contains a doubble package:
1) the pdf
2) the native data
the native data is to preserve editability. I would have to see the files to explain the quality differences.

 

[Al Ferrari]

[A comparable situation exists with regards to both EPS (Encapsulated PostScript) and PostScript files.
In the case of EPS, Adobe Illustrator can only fully and properly edit EPS files created by the current or
earlier versions of Illustrator. (dov)]

I recall a post by Dov saying Almost the same thing, but about pdf files and Illustrator. Can you cite the link where he says this about postscript/eps files and Illustrator?

Thanks,

Al

 

[Greg_Firestone]

To follow up on what Wharfrat posted, check the following settings when you save in Illustrator. Is this option enabled? If so, this includes the data mentioned in the quote from Dov.

Greg

 

[tmiller_iluvprinting]

Interesting, but if I uncheck 'Preserve Illustrator Edit Capabilities' and save the pdf the Illustrator pdf remains at about the same size. Does Illustrator Illustrator include the native data whether this is checked or not? Thanks everyone, great explanations!
Best,
Todd

 

[tmiller_iluvprinting]

I think this explains the size difference, but why the quality difference? The larger Illustrator pdf shows more detail/sharpness than the InDesign pdf, on the monitor, and on the proof. Is this because it is saving the native Illustrator data? Thanks again.
Best,
Todd

 

[Al Ferrari]

See the post by Dove Isaacs at 07-09-2009, 04:55 AM in this thread:

http://printplanet.com/forums/adobe/18564-opening-pdfs-illustrator

Al

 

[tmiller_iluvprinting]

Thank you Al-great info.
Best,
Todd

 

[rich apollo]

Interesting, but if I uncheck 'Preserve Illustrator Edit Capabilities' and save the pdf the Illustrator pdf remains at about the same size. Does Illustrator Illustrator include the native data whether this is checked or not? Thanks everyone, great explanations!
Best,
Todd

I did a quick test here, and a lot depends on the composition of the file. When I saved out a file containing vector and raster elements, turning off the Preserve Illustrator Editing Capabilities switch dropped the file size by ≈35-40%. A file containing only raster elements showed a little over a 70% reduction in file size. Each typeface added to the design diminished the difference in file sizes by a little.

Now, this is a very small file I'm playing with, so the percentage difference in file size is probably exaggerated.

 

[Lukas Engqvist]

If the file is an Illustrator file placed in InDesign and re-exported to PDF. When you place an AI file in Indesign it is placing the PDF part of the Ai file. Now depending on the settings when creating the AI you could be placing a PDF with a different value for rasterisation and flattening than the PDF you export straight from AI.

When an AI is refried (you place the PDF in InDesign and then export to PDF therefore this is a refry scenario) There may be a first and second conversion. Exactly what setting is affecting your quality? Hard to say, could be resampling of the portions of the image that are rasterised. It could be that strokes are converted to areas, or fills are converted to masked selections. As for file size it could be redundant information (outside the visible draw area) that is removed in one of the cases.