An undesirable white line occurs when printing press misregister occurs.

Although adding a "trap" around the blue box adds a slightly darker outline, it will help to avoid the dreaded white line which appears when shifting or misregister occurs.

Why do we need trapping software?

It is really a matter of taste. Good taste, as most printers and print customers will tell you. When printing a multi-color job there may be instances where the colors may meet or "butt". It is when this happens that trouble can occur. Not many printing presses can print the colors in perfect "registration" so they will not be able to butt the two colors perfectly. When this so called misregiester happens an unwanted white line will appear between the colors when the paper comes shining through.

Trapping software will create an overlapping combination of the two colors at the point where the two colors come in contact with one another. Although this will usually add a fine, slightly darker line around the object (sometimes just where the two colors meet), this is usually considered less objectionable and in better taste than the dreaded white line of paper showing through.

There are many different methods that you can employ to create successful traps. Trapping can be performed in many desktop applications with varying results. Software such as Quark Xpress, Adobe Illustrator and Photoshop are examples of applications which allow you to create digital files that are trapped. Most specialized commercial trapping software uses one of two methods. 1)Object oriented trapping, where you may dictate the trapping specifications on an object by object basis, and 2) Raster oriented trapping, applying traps after the image has been processed by a RIP (or rasterized). Trapwise, by ScenicSoft, uses the rasterized method, and Trapper, by DK&A, uses the object oriented method.

Which method is right for you depends on your goals, your equipment, your workflow and your customers.

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