[pdftex] Howto activate overprint (/knockout)

[the_shelter]

Hello JEBs,

Thursday, April 29, 2004, 8:15:28 PM, you wrote:

J> I'm developing a PDF document which shall be printed by a professional
J> printing company.

J> The whole document has a light-yellow background so that I need to 
J> activate (most times, but not always) the "black overprint" option as
J> well known/available in PS or PDF.

J> First I though it should be definable on color level but while searching
J> the whole web (and this ML) I couldn't find anything related which 
J> helped me except PDF native codes (/op /OP /OPM ...).

J> Now I'm sure that I'm on the right way but guess that I do something
J> stupidly wrong.

J> The way I tried to get it working is:

J> ----- snip ----- snip ----- snip ----- snip
J> ...
J> \pagecolor....

J> \pdfobj{<<
J> /op true
J> /OPM 1
 >>>}
J> \edef\opObj{\the\pdflastobj}
J> ...
J> ...
J> \color{black}
J> {\huge{\textbf{\pdfrefobj\opObj Test 5 6 7}}}
J> ...
J> ----- snip ----- snip ----- snip ----- snip

J> but it don't work. If I look into the PDF I can see the created object
J> as i.e. "8 0 obj ..." but it's never used ("8 0 R").
J> However I figured a lot with all the stuff like "\pdfliteral{<< /Type
J> /ExtGState /op true /OPM 1 >>}" too, but never got a working result :(.


J> Does anybody has an idea or knows a way ?

J> Thanks in regards
J>     JEBs
J> _______________________________________________
J> pdftex mailing list
J> pdftex at tug.org
J> http://tug.org/mailman/listinfo/pdftex

I am aware and have actually made the same thing work with the perl
module pdf::api2
There it is possible to set objects to overprint (I used it for color
seperation).
Search on CPAN and you'll find it. Be aware that though the library is
very powerful the documentation is rather poor since it is a "real
time project" which is used and developed on the demands of a real
project and therefore documentation is last.

Good luck,

 Weps