If you post a picture on the internet, it belongs to everyone.
That is
COMPLETELY WRONG!!! DO NOT EVER think that because something is on the net, that it is up for grabs. Anything from words, to photos, to music and artwork are still copyright protected and you DO NOT have the right to take, use or modify the item unless you have permission from the creator or it is posted as free ware where they say it is ok to use it! PERIOD! This also holds true for overseas in countries that agree to a couple treaties involving this issue. I'll tell ya it's a bear to fight overseas infringements.
I have a drawing used to sell products and to advertise my artwork services. People seem to love the image and I'm constantly having to do the following.
First you need to send the person a letter telling them they have infringed on your copyrighted photo. (in your case since you were being sneaky, I'd fess up you were testing him.. and then tell him he needs to remove it.)
I send this letter:
Dear Sir
I am the proprietor of the copyright artistic work of the "Cane Corso" (The "Work") being used in your logo. I have reserved all rights in the Work, which was first expressed in material form in 2008.
It has come to my attention that the image in your logo is identical to my copyrighted Work. Permission was neither asked nor granted to reproduce my Work and your Work therefore constitutes infringement of my rights. In terms of the Copyright Statutes, I am entitled to an injunction against your continued infringement, as well as to recover damages from you for the loss I have suffered as a result of your infringing conduct.
In the circumstances, I demand that you immediately:
1. Remove all infringing content and notify me in writing that you have done so;
2. Immediately cease the use and distribution of copyrighted material;
3. Undertake in writing to desist from using any of my copyrighted Work in future without prior written authority from me.
4. Be prepared to present for destruction, all marketable materials you have with this image.
I await to hear from you by no later than close of business on Wednesday, March 14th, 2012.
This is written without prejudice to my rights, all of which are hereby expressly reserved.
Yours faithfully,
Wendy S Hutchison
W S Hutchison Studios
The other option if he fights you or what ever is to file a DMCA with the website host. They will shut his website or
ebay page right down. He will then have to correct his site to comply with host infringement rules.