Hi,
I don't know if this will help, but here is the link from my Auctiva auctions for a picture, it appears that Auctiva changes the file name for each pic with numbers, in this case it relaced the original name with 18677717_o , and as far as I can tell, the numbers /1/6/6/3/4/9/ are my account with Auctiva since those numbers appear on all of my image links. You can get this link for your pics in the Images section.
Ricky
<img alt="" src="http://img.auctiva.com/imgdata/1/6/6/3/4/9/webimg/18677717_o.jpg"