wherein the first condition that requires a larger storage capacity of the storage unit in the document reading is {HEAD ~ a reading condition} where a difference is larger than an enough storage capacity to implement the functions other than the image reading function, which difference is {TAIL ~ a storage capacity difference} between: 
wherein the first condition that requires a larger storage capacity of the storage unit in the document reading is { HEAD ~ a reading condition } where a difference is larger than an enough storage capacity to implement the functions other than the image reading function , which difference is { TAIL ~ a storage capacity difference } between :
OTH OTH OTH OTH OTH 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 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 OTH OTH