Gamma

Correction,

Halftones, and

Screens

The following factors influence the quality of a halftone:

nPrinter resolution

nScreen frequency of the halftone

nQuality of the scan

nDiameter of the laser beam

Changing print resolution from 300x300 dpi to either 600x600 or 1200x600 dpi smooths the resulting spots. In addition, because each spot is represented by a wider range of dots, a greater the number of gray levels is possible. The laser beam is part of the print engine, so it’s not a factor you can adjust.

»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 Types

Your printer provides two different types of halftones—basic and advanced. These two options allow you to customize the smoothness of the printed image according to the number of grayscales it uses.

n Basic— Regular dot placement at 53 lpi for 300x300 resolution or 71 dpi for 600x600 resolution.

n Advanced—Variable dot placement according to the grayscale within the image. Generally, this option provides smoother transi- tions between grayscales within the image.

»Note: When the advanced halftone type is chosen, gamma correction has no effect on the image.

Screen Frequency

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.

Additional Technical Information

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