Image theft on the internet is so common that anyone posting a pic who doesn't take appropriate action to earmark their property (because they don't think it maybe stolen)... is fooling themselves.
Before you upload a pic, ANY pic, grab any one of many imaging software packages out there and type something that identifies you and the year you took it onto the face of the pic.
If you don't have any imaging software then head over to
www.downloads.com and find a freebie.