Screen frequency is the number of printer dots or
halftone cells per inch used to print grayscale images or color
separations. Also known as screen ruling or line screen, screen
frequency is measured in lines per inch (lpi)--or lines of cells per
inch in a halftone screen. The higher an output device's resolution,
the finer (higher) a screen ruling you can use.
The
relationship between image resolution and screen frequency determines
the quality of detail in the printed image. To produce a halftone image
of the highest quality, you generally use an image resolution that is
from 1.5 to at most 2 times the screen frequency. But with some images
and output devices, a lower resolution can produce good results. To
determine your printer's screen frequency, check your printer
documentation or consult your service provider.
Note:
Some imagesetters and 600-dpi laser printers use screening technologies
other than halftoning. If you are printing an image on a nonhalftone
printer, consult your service provider or your printer documentation
for the recommended image resolutions.
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