acquiring the image taking conditions at the time at which {HEAD ~ the image information} on {TAIL ~ the subject} are taken, 
on
acquiring the image taking conditions at the time at which { HEAD ~ the image information } on { TAIL ~ the subject } are taken ,
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH