Adobe InDesign CS4 - Manual (Page 498)

490 USING INDESIGN CS4
Trapping color
Trap assignments list the presets you have applied to various pages; the trap assignments are updated each time you click Assign.
1 In the Trap Presets panel, choose Assign Trap Preset in the panel menu.
2 For Trap Preset, choose the preset you want to apply.
3 Select the pages to which you want to apply the trap preset.
4 Click Assign, and then click Done.
Note: If you click Done without clicking Assign, the dialog box closes without making any changes to the trap assignments.
Trap assignments previously made using the Assign button are preserved.
Set up trapping page ranges
1 In the Trap Presets panel, choose Assign Trap Preset in the panel menu.
2 For Trap Preset, choose the preset you want to apply to the page ranges.
3 Select Range, and type one or more ranges in ascending sequence, using a hyphen for each range, and separating
pages and ranges with commas, or with commas and spaces. For example, 2-4, 6, 9-10, 12- is a valid range.
4 Click Assign, and then click Done.
To disable a trapping page range, choose Assign Trap Preset in the panel menu, type a page range, and choose [No
Trap Preset] in the Trap Preset menu. Click Assign, and then click Done.
Trap preset options
You can change trap preset options whenever you create or edit a trap preset. The same trap preset options are available
in Acrobat and InDesign. In Acrobat, you can view trap presets by choosing Tools > Print Production
> Trap Presets.
In InDesign, choose Window > Output > Trap Presets.
Trap widths
Trap width is the amount of overlap for each trap. Differences in paper characteristics, screen rulings, and printing
press conditions require different trap widths. To determine the appropriate trap widths for each job, consult your
commercial printer.
Default Specifies the trap width in points for trapping all colors except those involving solid black. The default value
is 0p0.25.
Black Indicates the distance that inks spread into solid black, or the holdback amount—the distance between black
edges and underlying inks for trapping rich blacks. The default value is 0p0.5. This value is often set to be 1.5 to 2 times
the value of the default trap width.
In InDesign, the value you set for Black Color determines the value for a solid black or a rich black, a process black (K)
ink mixed with color inks for increased opacity and richer color.
Updated 18 June 2009