User Guide

Canvas 12 User Guide
Choke trapping reduces the background knockout slightly
to trap into a dark foreground object.
Spread trapping enlarges the stroke of a foreground object
slightly to trap into a dark background object.
Trapping is a technique that purposely distorts the shapes of objects in color separations where
different colors meet. The slight distortion creates tiny areas called traps where colors overlap. The
trap areas can help avoid the appearance of gaps if the page is printed slightly out of register.
Before you use trapping in color separations, determine how likely it is that the piece will not be
printed in register. Consider how beneficial it will be to distort the shape of some objects to
compensate for possible misregistration; e.g., trapping type can ruin the appearance of the text, and
probably isn’t necessary.
Trapping choices
Canvas lets you specify two types of trapping, Choke and Spread.
Choke trapping: Used to make light background colors trap to dark foreground objects.
Canvas creates a choke trap by slightly reducing, (“choking”) the knockout area in the light
background object; e.g., if a dark blue “A” is printed on a pale yellow background with choke
trapping applied to the “A,” the “A” remains exactly the same, but the knockout area in the
yellow background becomes a slightly smaller “A” shape. The result is that some of the
yellow overlaps the edges of the dark blue “A.”
Spread trapping: Used to make light foreground objects trap into dark backgrounds. The
trap is created by slightly enlarging the foreground object without changing the knockout in
the background color; e.g., if a light circle is printed on a dark background with spread
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