When the bit map data is not compressed, {HEAD ~ an extra character} is registered into a predetermined area of {TAIL ~ a storage} 
When the bit map data is not compressed , { HEAD ~ an extra character } is registered into a predetermined area of { TAIL ~ a storage }
OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL