incrementing said position of {TAIL ~ said edge detection filter} in the second direction and resetting said position to said first direction origin of {HEAD ~ said image}; and 
incrementing said position of { TAIL ~ said edge detection filter } in the second direction and resetting said position to said first direction origin of { HEAD ~ said image } ; and
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH