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