An error measure is generated as a function of the decoded pixels of the decoded region and {HEAD ~ the previous pixels} of {TAIL ~ a previous region} 
of
An error measure is generated as a function of the decoded pixels of the decoded region and { HEAD ~ the previous pixels } of { TAIL ~ a previous region }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL