In order to determine whether a virtual slide image has any out of focus areas and is therefore a candidate for manual inspection, {HEAD ~ the various focus points} used to scan the virtual slide image are used to calculate {TAIL ~ a best fit surface} for the virtual slide image 
are used to calculate
In order to determine whether a virtual slide image has any out of focus areas and is therefore a candidate for manual inspection , { HEAD ~ the various focus points } used to scan the virtual slide image are used to calculate { TAIL ~ a best fit surface } for the virtual slide image
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH