{HEAD ~ One method} for producing the halftone screen is now explained in {TAIL ~ formal terms} for the gradation correction using a non periodic screen function 
{ HEAD ~ One method } for producing the halftone screen is now explained in { TAIL ~ formal terms } for the gradation correction using a non periodic screen function
HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH REL REL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH