A look at Acrobat Pro, Enfocus PitStop, Apago PDF Enhancer, and Callas pdfColorConvert.
One of the key strengths of PDF files is also PDF's achilles' heel:
It's not easy to edit a PDF file. If you want to create a file that
is "bulletproof"?meaning no one can inadvertently damage
the file in the production process"?then PDF is an almost ideal
medium. You can embed fonts and control color and assure
yourself that the file you
send the printer is the file
that will be output.
Unfortunately, we live in
a world that is not nearly so
ideal. The vast majority of
PDF files received by print
providers for output have
"issues." The fonts may not
be correctly embedded, the
color space may not be correct
for the intended output
(e.g. CMYK where spot color
is intended, RGB where CMYK is intended, or "rich black" where
black only is intended). and even if all of this is correct, there is
often a need to make last-minute changes"?a prospect that can
be extremely painful or even impossible without the proper tools.