Initially, a set of {TAIL ~ focus points} are identified that were used in {HEAD ~ the scan} of a virtual slide image 
Initially , a set of { TAIL ~ focus points } are identified that were used in { HEAD ~ the scan } of a virtual slide image
OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH