[pdftex] Bitmaps with transparent background?

[Dok, D. van]

> -----Original Message-----
> From: Sebastian Tannert [mailto:tannert at physik.hu-berlin.de]
> Sent: Thursday, February 22, 2001 12:06
> To: pdftex at tug.org
> Subject: [pdftex] Bitmaps with transparent background?

> Is it possible to include a bitmap graphic with transparent 
> background?
> And when it is possible, how it is done, I tried with PNG but
> this result in black background.
> May be PDF does not allow transparent background in bitmaps?
> 

I have a similar question: does pdftex have a concept of `layers' such as
would be found in graphical design tools? I've been successful so far
putting one thing over another by working bottom-to-top. I have the feeling
this works more by accident then by design.

In other words, does the PDF specification have a concept of `transparency'
and `layers' and, if so, how can it be addressed from pdftex?

regards,

Dennis van Dok