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