{HEAD ~ Apparatus} is provided for comparing the difference in the signals between the superimposed document and for analyzing {TAIL ~ the difference} to provide a signal related to the copy quality 
is provided for analyzing
{ HEAD ~ Apparatus } is provided for comparing the difference in the signals between the superimposed document and for analyzing { TAIL ~ the difference } to provide a signal related to the copy quality
HEAD HEAD HEAD HEAD HEAD REL REL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH