{HEAD ~ a density ratio setting module} that sets {TAIL ~ the ratio} of the density of the first chromatic color dots to the density of the second chromatic color dots, 
{ HEAD ~ a density ratio setting module } that sets { TAIL ~ the ratio } of the density of the first chromatic color dots to the density of the second chromatic color dots ,
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH