[texhax] Transparency or reduced saturation using Graphicx ?

[Philip TAYLOR]

Dear Colleagues -- I am including a large number (> 4000)
of graphic images in PDF format in a LaTeX document through
the medium of the Graphicx interface.   To achieve a nice
visual balance between the images (which were scanned at
different times, and processed using different technologies),
I can adjust the relative size of each.  But for some extremely
heavy images (see attached, which are the same abbreviation
in two very different scribal hands, and processed using
very different technologies), reducing the size is  insufficient :
what I really need is to be able to make the heavier graphic less
intrusive, either by rendering it partially transparent or
by mapping the fully saturated black to a less saturated grey.

I can find nothing in the Graphicx  documentation that suggests
that either of these is possible, but in the faint hope that
I have overlooked something, I am asking here.

Philip TAYLOR
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