User's Manual

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ADOBE PHOTOSHOP CS2
User Guide
5 For a color separation, choose from the following options:
• To have 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 Screens 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.
6 ForShape,choosethe dotshape youwant. If youwantall four screenstouse thesamedot shape, select UseSame
Shape For All Inks.
Choosing Custom from the Shape menu displays the Custom Spot Function dialog box. You can define your own
do
t shapes by entering PostScript commands—useful for printing with nonstandard halftone algorithms. For infor-
mation 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
fr
equency. If the resolution is more than 2.5 times the screen frequency, an alert message appears. 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.
See also
“Pixel dimensions and image resolution” on page 178
To save or load halftone screen settings
❖ In the Halftone Screens dialog box, do one of the following:
• To save settings, click Save. Choose a location for the saved settings, enter a file name, and click Save.
• To load settings, click Load. Locate and select the settings, and click Load.
Printing color separations
When preparing your image for prepress and working with CMYK images or images with spot colors, you can print
each color channel as a separate page.