WebThumb now has the ability to produce PNGs instead of JPEGs for snapshots. The PNGs are about twice the size of the JPEGs but they offer less artifacts and a much crisper thumbnail. Turning on PNG output makes a thumbnail cost 2 credits, to enable PNG output just add an output_type tag with a value of png. And example is shown below.
<webthumb> <apikey>apikey here</apikey> <request> <url>webthumb.bluga.net</url> <output_type>png</output_type> </request> </webthumb>