Aiyah... if put on internet, then be prepared that it'll be treated as available for own consumption in any way.
If you're concerned about it being taken and used without your knowledge, the best way i know of is to create the pictures using one of those FLASH programs. Disabling the right mouse click button protects you from the normal end user but not the HTML savy who will just grab the link off the source code.
This case is too small to garner much support. Unless you're living off these pictures and the "theft" has deprived you of your livelihood, in which case you might have a better case.
Edison Chen also can't get all those magazines, websites and newspapers to pay him for using his collection