Each constant area pixel is detected to be a white pixel or a black pixel and the white or black value is set with {HEAD ~ reference} to {TAIL ~ a local black or white reference point} 
to
Each constant area pixel is detected to be a white pixel or a black pixel and the white or black value is set with { HEAD ~ reference } to { TAIL ~ a local black or white reference point }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL