From a web designer point of view the best solution is to put in a watermark
You don’t have to get watermark software if you have jpeg editing
software that handles layers, just create a semi-transparent layer
and put it on top of the layer containing your image. Any attempts
to Copy and Save As will pick up the mark. If you use tables to
organize the images on your web page you can make the image you’re
trying to protect the background of the TD and a transparent or
semi-transparent image on top in the same cell.
For those of you who have used embedded watermarks, just an FYI that
there’s software out there that will strip the watermark code from
the jpeg and resave it. Aren’t we clever?
No one’s mentioned the lawyer approach yet. If the “not really a
wholesaler” that you are dealing with doesn’t agree to remove the
images, you might have to go this route. It’s not fun, and can get
expensive, but if you, at any time in the future, decide that you
don’t want someone to re-use your images (or designs) without your
permission you’ll have to be able to show that you’ve done
everything you can to protect them. If you leave them out there, the
re-user can claim that you implied consent to use by not doing
anything. I’m not a lawyer but went through a similar issue a few
years ago with some software I wrote.
Here’s hoping that “the not really a wholesaler” is nice and just
didn’t know any better rather than the other more nefarious
possibilities. Good luck!
(I just got a bag of pumice for soldering- who thought I’d ever pay
for a box o’rocks!)