I made a poster in AIllustrator for a scientific conference and was told by the printer to outline it before converting to pdf for printing. I was looking through the outlined and regular pdf and it appears that the outlined pdf has font that looks thicker in places and less well reproduced. For example, notice the heavier weight on the l in the attachment. I wanted to know if this is just how the pdf renders the outlined file and will be solved during printing or how can it be fixed if in fact these weird font changes will carry over to printing.

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Acrobat and reader have a small preference to enhance visibility of thin lines. This preference alters how a PDF may appear on screen but doesn't alter how it prints. This can often cause lowercase Ls and uppercase Is to look thicker than they actually are.....

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Here's a discussion at Adobe's site about that very issue.

Simply unchecking that preference item may cause you to see the ls and Is properly. Again, this is an on screen issue, not a print issue.

  • (+1) I did not know it was a feature that could be turned on and off. I always thought of it as the default way AA renders vertical lines, or even a bug. Good to know!
    – cockypup
    May 20 '14 at 18:45
  • Well.. It is arguably a bug in how it effects type rendering. It happens regardless of type being outlined or not. Adobe hasn't done anything about it in several versions.... so, they either feel it's "as designed" or are incapable of correcting it. However, users have been complaining about it for years.
    – Scott
    May 20 '14 at 18:47
  • "a well documented bug is a feature"
    – cockypup
    May 20 '14 at 19:27

I just learned from Scott's answer that what I thought was an artifact was an actual feature of Adobe Acrobat, so I have edited my answer and left it just as an illustration of how this feature alters the outlined copy.

This is an example of copy set to Myriad Pro Regular 12pt, then outlined, then saved as PDF. I opened in Adobe Acrobat and viewed it at 100%. Notice how many of the vertical strokes of the copy seem to be darker.

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Now, if I view it at 200%. the problem seems to disappear

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Apparently, and this is a guess, Adobe Acrobat, when the feature described in Scott's answer is active, rounds up the thickness of the vertical strokes to the closest pixel. This makes anti-aliasing unnecessary but makes the strokes look darker (because of the lack of semitransparent pixels) or thicker.

To check if this is what is happening in your case, open your outlined PDF and zoom in. Does the artifact disappear? If it does, I would not worry about it. You could also print a section of it at 100% to be extra sure.

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