Re: Transparent png

As an implementational detail (if that's a word) what we convert non-jpeg images 
into rgb or L. If there's an alpha channel it's converted to an image mask for 
those images. It was simple to allow for LA as well as as RGBA. For native (ie 
jpeg) images transparency is handled by making a specific color range into a 
mask. That also works for bitmap without the A channel.

Whether transparency has any real utility in printing is entirely another 
matter. It's certainly not clear whether printing inks on top of each other is 
the same as the additive process I see on my screen.
-- 
Robin Becker