The first block generating means splits {HEAD ~ the output picture} into {TAIL ~ a plurality} of blocks of a specified size which are then outputted sequentially 
into
The first block generating means splits { HEAD ~ the output picture } into { TAIL ~ a plurality } of blocks of a specified size which are then outputted sequentially
OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH