The second parameter is {HEAD ~ the difference} in {TAIL ~ “chroma}” which is the difference in “strong versus weak color.” 
in
The second parameter is { HEAD ~ the difference } in { TAIL ~ “ chroma } ” which is the difference in “ strong versus weak color . ”
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH