By comparing a digital image signal obtained by inverting {HEAD ~ a digital image} obtained from one of the scan lines by 180 degrees with a digital image signal obtained from the other of the scan lines, therefore, the tail 175 appears on {TAIL ~ both sides} of the pattern 171 as noncoincidence in the case where charge up has occurred in the pattern 171 
By comparing a digital image signal obtained by inverting { HEAD ~ a digital image } obtained from one of the scan lines by 180 degrees with a digital image signal obtained from the other of the scan lines , therefore , the tail 175 appears on { TAIL ~ both sides } of the pattern 171 as noncoincidence in the case where charge up has occurred in the pattern 171
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 OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH