determining {HEAD ~ means} for determining whether {TAIL ~ each pixel signal} read by the image reading means represents a white pixel and for generating a white pixel signal representing the white pixel 
determining { HEAD ~ means } for determining whether { TAIL ~ each pixel signal } read by the image reading means represents a white pixel and for generating a white pixel signal representing the white pixel
OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH