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