Setting Print Properties for Objects

Click on the Trap tab of the Object Specs palette to view the overprinting and trapping options for color separations. Click Apply to apply the settings to selected objects.

Overprinting in Color Separations

When you output color separations in Canvas X Draw, you can specify that an object should overprint, rather than knock out, objects behind it.

In color separations designed for commercial printing, a front object usually knocks out a hole where it overlaps other objects; however, you can apply the Overprint Object option to an object to prevent it from creating knockouts in objects behind it. This can compensate for registration problems on some printing presses.

For example, if you draw a cyan circle on a yellow background, Canvas X Draw knocks the circle out of the background in color separations so cyan and yellow don’t mix in the circle. If you select the circle and use the Overprint Object option, the circle prints over a solid yellow background, and the cyan in the circle mixes with the background yellow, resulting in a green circle.

The effect of the Overprint Object option is not visible on screen. This effect is visible only in the printed output when you produce color separations. Verify the settings for a particular object by viewing the Trap tab in the Object Specs palette and then selecting the object.

Color mixing as described previously is not the primary reason for overprinting. It’s more common for designers to overprint dark objects on lighter backgrounds as a way to prevent a gap from appearing between the colors if the press registration (alignment) isn’t perfect.

To Specify Overprinting for Objects:

1. Select the vector or text objects to be overprinted.
2. Select the Overprint Object checkbox on the Trap tab.
3. Click Apply. The appearance of the selected objects does not change on screen, but the objects will be overprinted in color separations.

To Remove Overprinting:

Select the objects and deselect the Overprint Object checkbox. Then click Apply.

Trapping in Color Separations

When objects of different colors touch, there is the potential for an unsightly gap to appear between the colors if the piece isn’t printed precisely aligned, or in register.

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 X Draw lets you specify two types of trapping, Choke and Spread.

• Choke trapping: Used to make light background colors trap to dark foreground objects. Canvas X Draw 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 trapping applied to the circle, the circle expands slightly to overlap, or trap into, the circle knockout in the dark background.

Trapping Limitations

Whenever possible, design illustrations to avoid certain trapping problems, and always discuss trapping with your service bureau and printer to avoid unnecessary expense and inferior results.

In Canvas X Draw, trapping is best applied to vector objects that use a solid pen stroke and solid pen ink color. The following limitations apply to trapping:

• Canvas X Draw will not create a choke trap for text.
• Canvas X Draw will not create a choke trap for a vector object that has no stroke or has a stroke that is not a solid pen stroke.
• Canvas X Draw will not create a choke trap for an object that has a gradient pen ink.
• Canvas X Draw will not create a spread trap for a paint object.

To Specify Trapping for Objects:

1. Select the object you want to trap. In most cases, this will be a foreground object that touches a highly contrasting color.
2. Click the Trap tab.
3. Select the Trap Object checkbox, and then click the Choke or Spread radio button. (See Trapping Choices.)
4. Click Apply to set the trapping option for the selected object. No change is apparent in the object on screen, because the trap is created only when you print color separations.

To Apply Trapping to Selected Text:

You can apply trapping options to text that you select within a text object using the Overprint and Spread options in the Text | Style menu.

To Adjust the Trap Size:

Before printing color separations, specify the trap size. Select the Separations options in the Print dialog box to change the trap size value.