Adobe PHOTOSHOP 6.0 Manual page 391

5 For a color separation, choose from the
following options:
• To manually enter the screen frequency and
angle, choose a color of the screen for Ink, and
enter the frequency and angle; repeat for each
color separation.
• To have Adobe Photoshop determine and enter
the best frequencies and angles for each screen,
click Auto. In the Auto Screens dialog box, enter
the resolution of the output device and the screen
frequency you intend to use, and click OK.
Photoshop enters the values in the Halftone
Screens dialog box. Changing these values may
result in moiré patterns.
If you are using a PostScript Level 2 (or higher)
•
printer or an imagesetter equipped with an
Emerald controller, make sure that the Use
Accurate Screens option is selected in the Auto
Screens dialog box (or in the Halftone Screens
dialog box if you're entering the values manually).
The Use Accurate Screen option lets the program
access the correct angles and halftone screen
frequencies for high-resolution output. If your
output device is not a PostScript Level 2 (or
higher) printer or is not equipped with an
Emerald controller, this option has no effect.
For Shape, choose the dot shape you want.
6
If you want all four screens to have the same dot
shape, select Use Same Shape For All Inks.
Choosing Custom from the Shape menu displays
the Custom Spot Function dialog box. You can
define your own dot shapes by entering
PostScript commands—useful for printing with
nonstandard halftone algorithms. For information
about using PostScript language commands,
see the PostScript Language Reference published by
Addison-Wesley, or consult the imagesetter's
manufacturer.
For optimal output on a PostScript printer, the
image resolution should be 1.5 to 2 times the
halftone screen frequency. If the resolution is more
than 2.5 times the screen frequency, an alert
message appears. (See "About image size and
resolution" on page 92.) If you are printing line art
or printing to a non-PostScript printer, see your
printer documentation for the appropriate image
resolutions to use.
7 Click OK.
To save halftone screen settings:
In the Halftone Screens dialog box, click Save.
Choose a location for the saved settings, enter a
filename, and click Save.
To save the new settings as the default,
hold down Alt (Windows) or Option
(Mac OS), and click the —> Default button.
To load halftone screen settings:
In the Halftone Screens dialog box, click Load.
Locate and select the settings, and click Load.
To return to the original default settings,
hold down Alt (Windows) or Option
(Mac OS), and click <—Default.
ADOBE PHOTOSHOP 6.0 381
User Guide