[NTG-pdftex] PNG handling, transparency

Hartmut Henkel hartmut_henkel at gmx.de
Tue Nov 2 21:55:05 CET 2004

On Tue, 2 Nov 2004, Hans Hagen wrote:

> > \immediate\pdfximage {mask.jpg}
> > \pdfximage attr {/SMask \number\pdflastximage\space 0 R} {img.jpg}
> >
> > The Hello shines through. Drawback: Seems that xpdf doesn't have any
> > idea of /SMask yet, the example works only with acroread and gs.
> Interesting, but it seems that the images must be kind of specisl,
> since it does not work on arbitrary ones

Soft-mask image must be DeviceGray type. BTW, with libpng-1.2.8beta2 the
pdftex crashes during PNG write have gone, and alpha is stripped as

Regards, Hartmut

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