If these are images you want people to see that they might but, make the
images relatively low-res and overlay a copyright notice on top of
(within) the original image. If you aren't reselling the images, but you
don't want enyone else reproducing them, expand the electronic image to
contain a blank border at the bottom (outside the original image) in which
you can place a copyright notice that is always seen when using a
graphical web browser.
-david