Comment on FM6 "PDF Optimization" + Acro5 "Optimize Space"

[Shlomo Perets <shlomo@xxxxxxxxxxxxx>]

FrameMaker 6 - "PDF optimization"

[note: I find the "PDF optimization" term to be confusing, as optimization
has a different & well-established meaning in the PDF and Acrobat literature,
but as this is the term used by FrameMaker, I'll use it nevertheless].

I tested the FM6 "PDF optimization" feature quite extensively after
FM6 was released. My TimeSavers had an UnBloat function which coped
with the excessive named destinations problem at the distilling level, and
I wanted to be able to tell current TimeSavers users whether they can
rely on "PDF optimization" after upgrading to FM6, instead of using the
UnBloat function.


My conclusions, included in the review of PDF-related aspects of FM6
(http://www.microtype.com/resources/FM6-PDF.pdf) were that even
though the new "PDF optimization" feature is definitely an improvement
over the crude 5.5.6 hidden "fix" (to be avoided at all times), it is
nevertheless not reliable nor efficient. In a few test books that I used,
there were several bad links as a result of this feature, and the PDFs
still had many unused destinations.

- If you are not concerned about the excessive destinations and the
resulting extra size and want to be "safe", you can use the
pre-FM6 mode of creating all destinations.

- If you are concerned about the PDF file size, you can try using the
FM6 optimization feature and check the results.

- Whether you use FM6 optimization or not, I recommend using a link
checking utility to analyze validity of interactive features in your PDFs.

Distiller may display messages about undefined destinations, which
is a clear indication of bad links. But Distiller does not report problems
with destinations if the target exists in another PDF (when you have
cross-file links/xrefs). So in a document collection you may have
many bad links even though Distiller does not not report any message
about undefined destinations.

To further complicate things, Acrobat itself does not produce an
error message when you activate a link to an invalid destination if the
target file exists - it opens the PDF at the default opening page, but
not at the specified destination, without letting you know that something
is wrong. So clicking invalid links in Acrobat may not reveal the fact
that something is wrong, unless you actually judge the results carefully.
And you typically have too many links to check with the appropriate
level of attention.

The only way to diagnose a document collection, in my opinion, is to
use a link checking utility in Acrobat. I recommend Ari's Link Checker
(www.dionis.com, US$100). Among other things, it can check an
entire folder or CD in one action, producing a report on all interactive
features.



Acrobat 5 - Optimize Space

Acrobat 5 has a new Tools > PDF Consultant > Optimize Space
function. The function is limited to analysis of standalone PDFs, and
the "Remove Unused Named Destinations" option, turned on by default,
does not check whether destinations are used by links in other files.
After running this function on a document collection, many links
that were previously valid become invalid.

This function is not to be used, unless you produce a single,
standalone PDF with no cross-PDF links.



For technical info on "PDF bloat", see
http://www.microtype.com/TimeSavers/SPTS-FM.pdf#UnBloat.

Each named destination adds ~100 bytes to your PDF file size. For
examples on size added to real-life PDFs due to excessive named
destinations, see http://www.microtype.com/TimeSavers/feedback.html,
under UnBloat.



Shlomo Perets

MicroType * http://www.microtype.com
FrameMaker-to-Acrobat: SP TimeSavers / Advanced Techniques Course / Solutions



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