the encoded region having been encoded as {HEAD ~ a skipped region}, if the error measure is less than a specified threshold value; otherwise, the encoded region having been encoded as {TAIL ~ the temporary encoded region} 
the encoded region having been encoded as { HEAD ~ a skipped region } , if the error measure is less than a specified threshold value ; otherwise , the encoded region having been encoded as { TAIL ~ the temporary encoded region }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD 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