The system further includes a programmed computer that determines whether each pixel is {HEAD ~ a constant area pixel} or {TAIL ~ an edge area pixel} 
The system further includes a programmed computer that determines whether each pixel is { HEAD ~ a constant area pixel } or { TAIL ~ an edge area pixel }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL