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