> yet the resulting PDFs put a keyline on - sometimes
Are you using layers? Try move the offending item to a different layer.
I've had this problem before as well and that usually solved it.
This is a common problem in commercial prepress workflows, so there's likely
relevance to your situation (Depending on how you "faded" the picture, of
If you took a greyscale TIF and coloured it a tint of a Colour (Black or
otherwise), unless you're printing directly from PM, chances are it will
convert back to 100% of that colour. If you create an EPS (or PDF) for a
composite prepress workflow, OPI comments must be used for the tints to
work. (i.e. Omit images must be selected). yes, a PDF will LOOK right, but
it will not print right.
The short of it is is that PM accomplishes the "tinting" by commenting the
postscript with a transfer function-like comment. Unfortunately, these
comments get ignored in the shuffle.... like when generating a PDF, or when
normalizing a PDF *BACK* to EPS, as is done frequently in some prepress
Basically, these days, you should always avoid using this method for tinting
a greyscale. You will be better off doing it elsewhere (i.e using Photoshop
for ghosting back or creating a tinted monotone)