QMS 860, User Manual, Page: 189 / 398

The higher the resolution of the printer, the smoother the resulting
spots, and the greater the number of gray levels possible because
each spot is represented by a wider range of dots. The laser beam
is part of the print engine, so it is not a factor that the user can adjust.
Screen Frequency is the number of lines of dots that compose
each inch of a halftone screen. The screen frequency of a halftone
determines the number of spots used to represent gray levels in a
given area. A 71 lines per inch (lpi) screen frequency has 71 lines
of dots for each inch of the halftone screen.
Figure 6.2 shows the relationship between screen frequency, gray
levels, and print resolution. As the screen frequency increases, the
number of gray levels decreases.
The number of gray levels that your printer can produce depends
on the screen frequency and the print resolution. The default value
for screen frequency using 600 dpi is 71 lpi. This typically allows
73 different levels of gray. The default value for screen frequency
0
50
100
150
200
250
42 53 71 106
51
201
33
129
19
73
9
33
300 x 300 dpi
600 x 600 dpi
Screen Frequency (lpi)
Gray Levels
Fig. 6.2 Gray Levels
Chapter 6
6 - 4 P r i n t Q u a l i t y