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