Watermark on all small preview images. how?

[stockdiv]

Want to set the small thumbs (preview iamges) for more then 200px.
As this, i need a watermark on them.
Someone know hot to get the watermarks on every image?
Think this will not work. Because we have only 1 option to add a watermark file.
Need a second smaller one.

[mj72]

Did you find a solution?

I've posted this on the wishlist:
viewtopic.php?f=22&t=1455