Yes...a difficult area indeed. Daz do give permission for png format. If a provider were, however, to deliver lots of images of say the millennium cat in all its poses, then I see a problem. Images are often supplied for postwork and this topic has been discussed time and time again!!!

See....http://www.renderosity.com/mod/bcs/index.php?ViewProduct=49315 for a product in their marketplace. This involves the medusa and both DAZ and the vendor state that "they have no problem with this".

I was under the impression that png images could be used and I can give you links to many sites that actually SELL them.

Hope this helps in some way!!!