I've seen threads where it is stated that google images could be blocked with this:
*google*tbm=isch*
However, I input this in the web filter under the blocked sites dialog and I can still search for say "porn" and get all kinds of porn images.
*google*tbm=isch*
However, I input this in the web filter under the blocked sites dialog and I can still search for say "porn" and get all kinds of porn images.