Update on Preview issues with weird PDF document

Posted by Pierre Igot in: Macintosh
March 19th, 2010 • 3:04 pm

Following my post yesterday about weird seemingly font-related issues in Snow Leopard’s Preview application, a couple of readers have written to provide more information.

One of them noted that he was also able to reproduce the same problem with the same sample PDF file in Tiger’s Preview application, i.e. in Mac OS X 10.4.x. So it looks like it’s not a problem limited to Snow Leopard.

(Unfortunately, I don’t have an entire lab of machines running various versions of Mac OS X that would enable me to easily check if problems are reproducible in systems older than Snow Leopard. Maybe one day our systems will be powerful and flexible enough that we can easily run virtual machines with older versions of OS X on our workstations, if only to be able to provide better advice and technical support to our various clients and obviously for testing purposes.)

Another reader noted that there was something very weird going on with my PDF sample file. There is no doubt about that. If, as he suggested, you open that sample file in Adobe Illustrator, you’ll see all kinds of garbage where text is expected to be, and the heading that appears as blocks of black and grey in Preview is actually not visible at all.

Attempting to select the text in the heading in Acrobat Pro, which does appear to display the heading properly, also reveals that it definitely does not behave like regular text in a PDF file. It seems to be a picture rather than text.

Yet the question remains: How come Acrobat Pro and Adobe Reader are able to display the heading text when Preview shows blocks of black and grey? (I won’t dwell on what Illustrator does.)

When it comes to files that are described as “weird” or “corrupted,” my response is always the same: Somebody somewhere created that file with the software tools that were available to him/her. If he/she could create it, then I should be able to read it. It’s not his/her fault if the software he/she uses is crappy and produces “weird” or “corrupted” files.

In this particular case, according to the information displayed in Acrobat Pro, the original PDF from which I extracted the sample page (the document exhibits the same problems on several different pages) was created using “Adobe Acrobat 8.1” and is supposed to be in PDF 1.6 format.

But of course, that only means that the file’s author used Acrobat to produce the PDF, not to author the file itself, which might have been done in some old version of Microsoft Publisher for Windows, for all I know.

Again, however, whatever the tools used by the author, even if they were used “improperly,” the fact remains that these tools had the ability/potential to produce such a “weird” PDF file, and that’s not the author’s fault.

Similarly, while I can understand that it is difficult to design a PDF reader that is able to read and render properly all the different flavours of PDF, no matter where they come from and what tools were used to author them, it still is the ultimate goal and promise of a “portable” format such as PDF. Which is why, while I can live with the bug/limitation in Mac OS X’s Preview, I still submitted a bug report and I still expect Apple to improve Preview some day so that it can also read and render these weird PDF files properly. After all, if Adobe Reader and Acrobat Pro are able to do it, then so should Preview.

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