calculating an evaluation function by means of the gray level ratio by repeating {HEAD ~ the gray level ratio} calculating {TAIL ~ step} in the specified area 
calculating
calculating an evaluation function by means of the gray level ratio by repeating { HEAD ~ the gray level ratio } calculating { TAIL ~ step } in the specified area
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH