Online Seminars from Photoshop Tips & Tricks...

Photoshop 5.5
Spot Color Trapping
by Joyce Evans

We will trap the sample we did in Spot Color Knockout and then change the percentage of the Spot Color for print. If you don't fully understand the principles of "knockouts" and trapping, see Fred's article "Trapping: Dangerous Subject" in the Graphics department of DT&G.
__ Whenever you have two colors which vary as much as these do you'll need to trap them. The knockout we made and the spot color are the exact same size. If the press gets the registration a tad off (which almost always happens) you'll have a white hairline showing through. To solve this you need to either make the knockout a bit smaller or expand the spot color.
PHOTOSHOP Seminars - Color Trapping__ We are going to expand the spot color. Don't even try to use the trapping that Photoshop has because it won't work in the Spot Color Channel, you have to do it manually. It isn't all that difficult.

Most offset printing applications require about .25 points of trap. There are 72 points in an inch. To determine how many .25 points there are in an inch, divide 72 by.25 which is 288.

Now we need to determine how to get this into pixels. Divide your resolution (ours is 200) by 288. Multiply the result by 2 and round off to the nearest whole number to determine the stroke width. (always round up)

Based on our calculations above we need to stroke 2 pixels

CTRL+Click (Option+Click) on the Spot Color channel to select it.
PHOTOSHOP Seminars - Color Trapping

Be sure you have your foreground color set to the color of your Spot
color, so the stroke is the same color.

From the menu bar choose Edit|Stroke and enter a value of 2 pixels and
center, click OK.

You probably think you just increased the size by 2 pixels but in fact
it was only one because we choose center which put one pixel on the
current selection and one outside.

Now that wasn't so bad was it? You have just trapped your Spot Color.

Joyce Evans is a freelance reviewer. If you have software or hardware you would like reviewed please send press releases or contact at: Copyright 2000 All Rights Reserved Joyce Evans

[ Design Center ] _ [ Photoshop Tips & Tricks ] _ [ Seminars ] _ [ Designers' Bookshelf ]
[ The Photo Warehouse ] _ [ The Desktop Publishing Jumpstation ]

Want to discuss it? Subscribe to The Designers' CAFE

Photoshop is a registered trademark for Adobe Systems, Inc. Mountain View, CA.

Thank you for visiting the Photoshop Wing in The Design & Publishing Center , at Copyright 1994 - 2001 , Showker Graphic Arts, for the The Design & Publishing Center, ALL RIGHTS RESERVED. Contact The Design Center design team for web page critique, makeover clinics, or website design, production and hosting.

Writers, Designers, Consultants, Publishers are encouraged to become published in The Design Center Publications!
Design & Publishing Center is a Spam-Free, reader-driven web site
This is a Spam-Free web site. Help support a healthier Spam-free environment!

The Design & Publishing Center is an Affiliate of The Graphic Design Network at
Graphic-Design.Net, Amazon Books at, as well as The News-Serve Network at, The User Group Network at, The User Group Academy at, and The Desktop Publishing Jumpstation at ........ Notes: The screen shots herein represent the copyrighted works of their respective owners, and are used here for editorial demonstration purposes. please read and be aware of our Legal Properties & Disclaimers document. Not all areas of the online environment allow special characters such as the registration and trademark marks. This file will alert you to proprietary works that cannot be duplicated or distributed. Copyright 1996, 1997, 1998, 1999, by Showker Graphic Arts, The Design & Publishing Center, on behalf of the respective authors and artists. ALL RIGHTS RESERVED. &photographic, Photoshop Tips & Tricks, &Type, WebDesign & Review, and Pixelsmith are all trademarks for The Design & Publishing Center. Other products mentioned in these pages are the registered trademarks of their respective owners.