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475
Adobe Photoshop Help
Printing (Photoshop)
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475
Selecting halftone screen attributes
Halftone screen attributes include the screen frequency and dot shape for each screen
used in the printing process. For color separations, you must also specify an angle for each
of the color screens. Setting the screens at different angles ensures that the dots placed by
the four screens blend to look like continuous color and do not produce moiré patterns.
Halftone screens consist of dots that control how much ink is deposited at a specific
location on-press. Varying their size and density creates the illusion of variations of gray
or continuous color. For a process color image, four halftone screens are used: cyan,
magenta, yellow, and black—one for each ink used in the printing process.
Halftone screen with black ink
Halftone screens with process ink at different screen angles; correctly registered dots form rosettes
In traditional print production, a halftone is produced by placing a halftone screen
between a piece of film and the image and then exposing the film. In Photoshop, you
specify the halftone screen attributes just before producing the film or paper output. For
best results, your output device (a PostScript imagesetter, for example) should be set to
the correct density limit, and your processor should be properly calibrated; otherwise,
results can be unpredictable.
Before creating your halftone screens, check with your print shop for preferred frequency,
angle, and dot settings. (Use the default angle settings unless your print shop specifies
changes.)
To define the screen attributes:
1
Choose File > Print with Preview.
2
Select Show More Options, choose Output from the pop-up menu, and click Screen.
3
In the Halftone Screens dialog box, choose whether to generate your own screen
settings:
•
Deselect Use Printer’s Default Screens to choose your own screen settings.
•
Select Use Printer’s Default Screens to use the default halftone screen built into the
printer. Photoshop then ignores the specifications in the Halftone Screens dialog box
when it generates the halftone screens.
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