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