I recently discovered TinEye reverse image search.
Using it has been an eye-opening experience.
I had never realized how many web sites out there had no qualms about using my photos without ever asking for permission.
Now, over time, I have received a few requests to use my photos and/or charts, some even accompanied with generous offers to pay. I am not averse to giving permission so long as proper credit is given. However, when someone just copies one or more of my photos or charts to his server without asking for permission, without an opportunity for me to say, for example, just providing a backlink is enough or coming to some other reasonable arrangement, well, that is crossing the line.
So far, hosting providers and domain registrars have been cooperative in helping me deal with these copyright violations.
I recommend that you try TinEye reverse image search if you have put any of your work online. You never know what you will discover.