PS/PDF API Change Proposal: (Re: [cairo] Semanticsof transparent objects)

Dirk Schönberger dirk.schoenberger at
Thu Jan 19 00:39:20 PST 2006

> The question is, do you get something different with:
>  alpha=0.5 red
>  alpha=1.0 pink
> My understanding is that with PS/PDF, no, you don't. The infrastructure
> just isn't really there for supporting printers with white opaque
> inks. (Such things might exist for printing labeling onto colored
> plastic, say.)

Perhaps this should be left to the actual postscript printer?
In Adobe Illustrator file format (which is similar to Postscript), there
exist a "overprint" operator / overprint mode.

In this mode white colour areas are supposed to be printed, instead of
silently ignored because of assumed white paper.

This still has to be supported by the "backend" printer, of course.


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