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Imperfect registration of the printing presses at your printer could ruin your documents. Let Real World Adobe Indesign 1.5 author Olav Martin Kvern show you how to trap your publications to avoid disastrous printing results.

[Part 3 of 6]

Trapping Across Color Boundaries. The techniques described above work well as long as objects don't cross color boundaries. If the objects do cross color boundaries (especially going from a color background to a white background), it's too obvious that you've changed the shapes of the objects. What do you do?

  1. Drag the ellipse so that it 's partially outside of the rectangle.

  2. Clone the ellipse. To do this,copy the object to the Clipboard, then press. Command-Option-Shift-V/Ctrl-Alt-Shift-V. This creates a copy of the ellipse exactly on top of the original ellipse.

  3. Without deselecting the cloned ellipse, press F10 to display the Stroke palette, if it's not already visible. In the Stroke palette, enter a stroke weight for the trap in the Weight field.

  4. Turn on the Overprint Stroke option in the Attributes palette.

  5. Select the ellipse, then note the values in the X and Y fields of the Transform palette.Press Command-X/Ctrl-X to cut the ellipse.

  6. Select the background rectangle and choose Paste Into from the Edit menu.

  7. Select the original ellipse and press Command-Shift-[/Ctrl- Shift-[ to send it to the back.

  8. Using the Direct Selection tool, select the ellipse you pasted inside the rectangle. If the ellipse did not appear in exactly the same position as it occupied before you pasted it inside the rectangle, enter the X and Y values you recorded earlier in the X and Y fields of the Transform palette. InDesign moves the copy of the ellipse into the same position as the original ellipse.

At this point, the ellipse you pasted inside the rectangle spreads slightly, while the part of the ellipse outside the rectangle remains the same size and shape. Choose Revert from the File menu to get ready for the next trapping example.

What happens when the object you need to trap overlaps more than one other, differently colored object? In this case, you can run into trouble. The trap you use for one background color might not be the trap you want to use for the other. You might want to spread one and choke the other,depending on the colors you're using.

In these cases, you can use the same basic techniques described above for the overlapping and/or abutting objects. But, at this point, I have to urge you to save yourself some trouble and use either of InDesign 's automatic trapping methods.

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