[pdftex] Image transparency

George N. White III WhiteG at mar.dfo-mpo.gc.ca
Thu Jun 21 15:11:49 CEST 2001

On Thu, 21 Jun 2001, Michael Chapman wrote:

> A lively list !  Think my query has promoted some sixteen emails (in less
> than 24 hours) !
> However, unless I missed it, no one has responded to my original point:
> Basically can I put my octagonal PNG image onto pdfscreen pages without the
> "frame" being filled in at the corners in white ?

I don't know of a way to do this without changing pdftex.  You would need
to figure out how to get pdftex to use the "transparency" info from your
PNG images -- I expect this is currently ignored.

You might be able to convert your PNG files to PDF with the transparency
preserved using some other tool, but I just tried this with a file that
loads a PNG background and adds some annotations. If I convert the PNG to
PDF (using ImageMagick's convert and manually editing MediaBox) the
annotations are lost, so even if you can get transparency into your PDF
version of the image it may not work properly.

Ghostscript's pdfwrite device has improved at lot, maybe you can
do something more quickly using Postscript (like editing the files
in Illustrator).

George N. White III <gnw3 at acm.org> Bedford Institute of Oceanography

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