Glenn suggests:

> > How can I set up my image files (i.e. JPEG) in an HTML page
>  > so that it will display but not allow the user to download?
>
>  Rather than take this angle, perhaps it is sufficient to
>  "watermark" the image so that it displays without apparent
>  artifacts, but so that you can prove the image is yours

That watermark (which is normally done by writing some sort of signature into
the low order bits of an image, across many pixels, so that it can't really
be seen in the image) lasts exactly as long as the image is not manipulated
in any manner (made larger, smaller, cropped or converted into another
graphic format). At that point, the watermark is gone.

Wirt Atmar