[pdftex] bitmap with clipping path

[Kester Clegg]

Stephan Lehmke <Stephan.Lehmke at cs.uni-dortmund.de> writes:

> Hi all,
> 
> I have the following problem:
> 
> I'm trying to move a catalogue which is currently made 
> by hand in quark to data-based generation using pdftex
> as `print engine'.
> 
> One problem are product photos. So far, the raw photos are 
> augmented with a `clipping path' in photoshop. In quark,
> the clipped out parts are underlaid with a special (pantone)
> color. No problem with color separation and printing, of
> course.
>

OK, you've two problems here I think.  I think paths can be stored in
the gimp, but neither me or this list is the place to discuss that.  But
presumably you can get the clipped photos out of photoshop, where they
can stored as png formats.  So...

[...]


> What I need is this:
> 
> In the beginning, there is a photo augmented with a clipping path 
> in photoshop.
> 
> In the end, there is a document processed by pdftex, containing the
> correctly clipped bitmap underlaid with the special color.
> 
> Inbetween, there is any kind of (scriptable) process in which 
> the photoshop image is made digestible for pdftex...
> 

> Photoshop can save in different formats, among them eps, but 
> it seems neither ghostscript nor distiller can make anything
> out of the clipping path contained in the eps...
>

and pdftex doesn't like eps anyway.  But it does like png, and png can
handle transparency, or put another way, your alpha channel...
 
> It is also possible to convert the clipping path into a mask
> (color or alpha channel), but how to process this information?
>

So can't you convert your clipping path to an alpha channel, cut, fill
with your special colour (or use a lower layer, and fade in your clipped
photo), save output as jpeg or png.   Or if you insist as eps, then use
epstopdf and then link to the file in your pdf document?
 
> In principle all I need is any kind of (scriptable) process
> which takes a masked or clipped bitmap and a colored patch
> of the right pantone color and overlays the two, yielding a
> correct pdf image.
> 

Don't try and overlay would be my advice.  Do all your processing first,
output as jpeg or png and include that.

> c) postprocess photoshop pdf
> 
> In principle, the photoshop-produced pdf is ok, only the
> pantone color is replaced by a cmyk color (maybe a newer
> version of photoshop can do better? or does this depend

Wel, you could just embed the pdf produced by photophop into your
document.  There was a post on this topic quite recently:

http://www.ctan.org/tex-archive/macros/latex/contrib/supported/pdfpages/

> Maybe there is a tool especially for this task?

That'll be the tool your making, right?!  ;-)

Good luck,
k.

-- 
************************************************************************
Kester Clegg 			Dept. of Computer Science,
Research Associate (UTC)	University of York, UK

Tel (01904) 43 27 49		email: kester at cs.york.ac.uk
************************************************************************