About GammaCorrectionQMS 1725E Print System Reference5-4TermsSeveral terms related to gamma correction are explained in this sec-tion to help you better understand the gamma correction concept.Gray LevelsGray levels are a progressive series of gray tones between black andwhite. Gray levels are obtained by varying the ratio of black to whitedots. The number of gray levels depends on printer resolution andscreen frequency.HalftoneA halftone is a printed copy of a scanned image as a set of tiny,evenly spaced spots of variable diameter that, when printed, visuallyblur together to appear as shades of gray. Your QMS 1725E PrintSystem creates halftone cells by mapping each gray level onto a col-lection of dots.Factors that influence the quality of a halftone aren Device resolution of the printern Screen frequency of the halftonen Quality of the scann Diameter of the laser beamChanging print resolution from 300x300 dpi to 600x600 dpi smoothsthe resulting spots. In addition, because each spot is represented bya wider range of dots, a greater number of gray levels is possible. Thelaser beam is part of the print engine, so it’s not a factor you canadjust.Screen FrequencyScreen frequency is the number of lines of dots that compose eachinch of a halftone screen. The screen frequency of a halftone deter-mines the number of spots used to represent gray levels in a givenarea. A 71 lines per inch (lpi) screen frequency has 71 lines of dotsfor each inch of the halftone screen.
