{HEAD ~ The local reference point} is also adjusted as {TAIL ~ a function} of the value of each local extremum or nonextremum pixel after it is detected 
is adjusted as
{ HEAD ~ The local reference point } is also adjusted as { TAIL ~ a function } of the value of each local extremum or nonextremum pixel after it is detected
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH