If the error measure is less than a specified threshold, then {HEAD ~ the region} is encoded as {TAIL ~ a skipped region}, otherwise the region is encoded as the temporary encoded region 
If the error measure is less than a specified threshold , then { HEAD ~ the region } is encoded as { TAIL ~ a skipped region } , otherwise the region is encoded as the temporary encoded region
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH