Adobe InDesign CS3 - Manual (Page 592)

INDESIGN CS3
User Guide
585
Display or output spot colors using Lab values
Some predefined spot colors, such as colors from the TOYO, PANTONE, DIC, and HKS libraries, are defined using
Lab values. For backward compatibility with previous versions of InDesign, colors from these libraries also include
CMYK definitions. Lab values, when used in conjunction with the correct device profiles, give you the most accurate
output across all devices. If color management is critical to your project, you might prefer to display, export, and print
spot colors using their Lab values. The Ink Manager option Use Standard Lab Values For Spots lets you control which
color mode InDesign uses for these predefined spot colors: Lab or CMYK. If you need the output to match earlier
versions of InDesign, you should use the CMYK equivalent values.
Note: To improve on-screen accuracy, InDesign uses the Lab values automatically if Overprint Preview is on. It also uses
Lab values when printing or exporting if you’ve selected Simulate Overprint in the Output area of either the Print or
Export Adobe PDF dialog box.
1 Choose Ink Manager in the Separations Preview panel menu.
2 Do one of the following:
• For Lab values, select Use Standard Lab Values For Spots.
• For CMYK values, deselect Use Standard Lab Values For Spots.
See also
“Ink Manager overview” on page 583
About halftone screen frequency
In commercial printing, continuous tone is simulated by dots (called halftone dots) printed in rows (called lines or
line screens). Lines are printed at different angles to make the rows less noticeable. The Screening menu in the Output
section of the Print dialog box displays the recommended sets of line screens in lines per inch (lpi), and resolution
in dots per inch (dpi), based on the currently selected PPD. As you select inks in the ink list, the values in the
Frequency and Angle boxes change, showing you the halftone screen frequency and angle for that ink.
A high line-screen ruling (for example, 150 lpi) spaces the dots closely together to create a finely rendered image on
the press; a low line-screen ruling (60 lpi to 85 lpi) spaces the dots farther apart to create a coarser image. The size of
the dots is also determined by the line screen. A high line-screen ruling uses small dots; a low line-screen ruling uses
large dots. The most important factor in choosing a line-screen ruling is the type of printing press your job will use.
Ask your service provider how fine a line screen its press can hold, and make your choices accordingly.