defining a partial image in the specified area, the partial image being composed of {TAIL ~ a target pixel} and peripheral pixels on {HEAD ~ a line} in a specified direction in which the target pixel exists 
defining a partial image in the specified area , the partial image being composed of { TAIL ~ a target pixel } and peripheral pixels on { HEAD ~ a line } in a specified direction in which the target pixel exists
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH