{HEAD ~ The method} 19 wherein the function is {TAIL ~ a logical function} including the minimum or maximum of the height and gray scale values 
{ HEAD ~ The method } 19 wherein the function is { TAIL ~ a logical function } including the minimum or maximum of the height and gray scale values
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH