[pdftex] Howto activate overprint (/knockout)

[JEBs]

>>Yes, I'm aware that it will work and I know that it could be done with
>>the PDF internal "/op", "/OP" and "/OPM" parameters.
>>But my problem is how to integrate them in pdflatex.
>>I figured a lot with \pdfobj, \pdfrefobj and \pdfliteral but couldn't
>>get a working solution.
>>I get the object in but don't get them used/referenced nor working.
>>I'm sure that I'm doing something stupidly wrong but don't know what :/.
>>In addition I couldn't find any real useful docs/samples about the use
>>of the extended \pdf... commands.
>>
>>Any more suggestions ?
>>
>>Cya
>>   JEBs
>>    
>>
>
>Maybe a variant black with yellow in it would solve your problem.
>  
>
That's exactly the way as I make it right now, but it's not really the 
right way and prevents last time changes inside the PDF, like changing 
the backgound denstity when already in the printing agency...

Using the /op attributes together with \pdfliteral or \pdfobj would be 
exactly the right way, except that I couldn't firgure out the right 
syntax how to use them together in pdftex.

:(

Cya
  JEBs