{HEAD ~ a storage capacity} required to store {TAIL ~ one page} of the second read data output from the second image reading unit; and 
required to store
{ HEAD ~ a storage capacity } required to store { TAIL ~ one page } of the second read data output from the second image reading unit ; and
HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH