Transparency and PNG format

[graham samuel]

Folks, I've got a number of small GIFs in an app, representing human  
figures - therefore not rectangular. I managed to give each one a  
transparent background and RR honours this when I import the GIFs as  
images (i.e. the background information on the card shows up around  
the shape of the figure).

I've now started to using PNGs rather than GIFS, and I can give them  
transparent backgrounds in exactly the same way as the GIFs  
(GraphicConverter on the Mac is really good for this - a lot simpler  
than Photoshop Elements... but I digress). However when I import a  
PNG as an image, the transparency disappears and the figure therefore  
appears in a white rectangle. I can fix this with inks, but only on  
the Mac, and this app is destined for PC users mostly.

I've looked at the docs, but I can't see a way of telling RR to use  
the transparency in a PNG. I see a bit about Alpha Channels, but I  
don't know if I'm using an Alpha Channel or not, and anyway I can't  
understand how RR deals with them. I can of course convert all my  
PNGs to GIFs, but is this the only solution? (This leads me to ask if  
is there any disadvantage to using GIFs over PNGs - I kind of thought  
there was, but I'm no longer sure why).

Can anyone clarify this for me?

TIA

Graham


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Graham Samuel / The Living Fossil Co. / UK and France