[NTG-pdftex] PNG handling, transparency

[Hans Hagen]

Hartmut Henkel wrote:

> seems so yes: the alpha channel, if it would be properly extracted. Or
> use a separate image, tried just the maybe most trivial case:
> 
> \pdfcompresslevel=0 \nopagenumbers
> \immediate\pdfximage {mask.jpg}
> \pdfximage attr {/SMask \number\pdflastximage\space 0 R} {img.jpg}
> \leavevmode
> \rlap{Hello}%
> \rlap{\hbox{\pdfrefximage\pdflastximage}}\bye
> 
> 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

Hans

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