attribute-> thumbnail 100x100 produces jpgs even when reference element is .png

[redDolt]

Hello all, 

I've got a question about how the attribute element works. We have a product based website in Management Sever 10.1 Each product has an image (previously always jpg) and we've modified the template to have a thumbnail produced, which we've done using the attribute element; worked great till this week. 

Some of our new product pages are using .png images with a transparent background (we use the images for other things off our web server) and when it creates the thumbnail the file is coming out as a jpg. It would be ideal if the file types matched as we'd like to make use of the png thumbnails (specifically for the knocked out backgrounds). Is there any way to adjust how the attribute element produces that thumbnail?

I thought about saying the hell with it and just creating a second image placeholder and referencing the existing one but CMS is telling me that isnt allowed. I guess you can only do that with standard text fields and such?

Anyway, any thoughts on this are appreciated. 

DP