[Scribus] transparency question

Jan Schrewe jschrewe
Tue May 15 02:50:33 CEST 2007

avox schrieb am Montag, 14. Mai 2007:
> jrm wrote:
> > Hi,
> >
> > This regards using png images with portions that are
> > 100% transparent.  What seems to happen is that this
> > kind of transparency is respected even when exporting
> > to PDF 1.3 (as seen in acroread and kpdf), which is not
> > what I was expecting.  So I'm wondering if this is
> > too good to be true, that I may be able to use this
> > kind of transparency without restriction on what PDF
> > version to use, maybe even PDF/X-3...  The question is,
> > can I rely on this behaviour?
> >
> > What I guess was expecting was that since "PDF 1.3 does
> > not allow transparency" the transparent part of the png
> > would be made white, or maybe black.
> AFAIK PDF has supported hard masks for images from the beginning
> (that's also possible in PostScript using the imagemask operator).
> What is only possible since 1.4 is softmasks (alpha channel), since
> those require blending imagepixels with background pixels.
> I don't know if the behaviour for images with an alpha channel which
> contains only 0% and 100% values is defined, better not rely on that.
> Using an indexed palette with a special color for 'transparent' should
> work.
> /Andreas


Though I don't know the standard, I got my X3 PDf printed corrctly, when using 
100% transparency in PNG and tiffs.

This always seems to work, I use this bug/feature (?) every month, when I make 
a flyer.


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