During each scan line of regular scanning, dark cells are sampled and produce {HEAD ~ a voltage} that is modified by {TAIL ~ the offset voltage} that was determined during calibration 
is modified by
During each scan line of regular scanning , dark cells are sampled and produce { HEAD ~ a voltage } that is modified by { TAIL ~ the offset voltage } that was determined during calibration
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH