{HEAD ~ The local reference point} is then adjusted as {TAIL ~ a function} of the input value of each constant area pixel 
{ HEAD ~ The local reference point } is then adjusted as { TAIL ~ a function } of the input value of each constant area pixel
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