QMS 1660, Reference Manual

Page: 104 / 306

Gamma
Correction,
Halftones, and
Screens
QMS 1660 Print System Reference 5-4
Configuring the printer through the control panel is described in chap-
ter 4, “Printer Configuration,” of this manual.
Gamma Correction, Halftones,
and Screens
Gamma correction is the compression or expansion of the ranges of
dark or light shades in a printed image to provide the best copy of
scanned images.
Terms
Several terms related to gamma correction are explained in this sec-
tion to help you better understand the gamma correction concept.
Gray Levels
Gray levels are a progressive series of gray tones between black and
white. Gray levels are obtained by varying the ratio of black to white
dots. The number of gray levels depends on printer resolution and
screen frequency.
» Note:
The number of gray levels at 600x600 dpi and 1200x600 dpi is
the same. The enhanced print quality is due to elongated halftone
cells rather than to an increased number of gray levels.
Halftone
A halftone is a printed copy of a scanned image as a set of tiny,
evenly spaced spots of variable diameter that, when printed, visually
blur together to appear as shades of gray. Your QMS 1660 Print Sys-
tem creates halftone cells by mapping each gray level onto a collec-
tion of dots.