Acrobat How-To: Using Overprint Preview for Soft-Proofing

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Adobe Acrobat and Adobe PDF is the preferred soft-proofing method for printers, marketing departments, and agencies the world over. Overprint preview within Adobe Acrobat allows users to get a quick understanding of the most-minute details of the production process – getting overprints right, for instance. In addition to the tremendous value of creating PDF documents and engaging in review cycles with your clients, Acrobat is also focused on important details to ensure your documents output reliably, and exactly as you intended. The Craft vs. The Science The "craftspeople" in the print-production world have long been aware of the difficulties in specifying overprints and knockouts. In the days when they were created on film and camera, overprints and knockouts were complicated processes that required deep knowledge of production methods. In many ways, software applications haven't made it much easier. The high-tech, mouse-driven science of page layout and print production still requires intimate knowledge of press behavior and press operators are still required to deliver high-quality output no matter what kind of overprinting is involved. Proofing overprints has also been difficult. Older production applications are incapable of displaying overprints on screen, so creators and printers were forced to play a guessing game when it came to specifying overprint behavior. With Acrobat 5 (along with a host of other Adobe applications), guesswork is no longer required; users can simulate overprints on their monitors and desktop printers. Making Overprint Behave If you're taking notes here, make sure the first one is to call your service bureau or print-production provider to discuss overprinting behavior with them. Due to implementations of PostScript RIP technology, some RIPs will treat and specify overprint behavior differently than others. Because overprinting is very situation-specific, a good dialog with your print provider is a must. In Acrobat Distiller, under the "Color" tab, there is an option to "Preserve Overprint Settings." Use this to ensure that overprint information specified in your PostScript output to Distiller is preserved when your PDF is created. The resulting overprints in the PDF file can be displayed using the Overprint Preview functionality of Acrobat. Overprint Preview in Acrobat Acrobat 5.0 introduced overprint preview to the world of PDF. It allows users to gain an estimation of how overprint behavior will appear in a print condition. Working in harmony with soft-proofing and color management in Acrobat, users can gain a good estimation of how the job will look without having to jump through a lot of hoops to do it. These two screen shots illustrate how Overprint Preview can help detect critical flaws in the document. All three objects in this artwork are set to overprint, fill and stroke. Turning on overprint preview demonstrates how this will look when printed on a printing press (see figure 1). Working with Overprint Preview off, it is impossible to tell how those colors will output if they are set to overprint (see figure 2).

Figure 1: Overprint turned on. Figure 2: Overprint turned off.

When you're working with transparent artwork, or adding drop shadows to your content, overprint behavior is especially important. In this example, the cyan, magenta, and yellow circles are all set to overprint fill and stroke. Then, a drop shadow is applied to all three circles (blend mode of Normal, Opacity 75%). Instantly, you can see why Overprint Preview can prevent you from making big mistakes! (see figure 3) Seeing this on screen (and not having to rely on a telephone message, or a hand-written description of the problem) can save you from a costly output error.

Figure 3: Overprint preview can help prevent ghastly mistakes resulting from drop shadows and other effects.

Another common problem in working with overprints is placement of light-colored objects on the top of darker objects. In the example below, the "100% Color" text is filled with a 100% yellow value, and set to overprint. Using Overprint Preview, we can see what we'd expect in the printed output, and it isn't good (see figure 4). This is another example where overprint preview can provide users with instant notification that something will produce undesirable results on output (see figure 5).

Figure 4: Light objects on dark colors are recipes for disaster. Figure 5: Overprint preview can give you the information to correct the situation long before going to press.

These basic examples of Overprint Preview Acrobat clearly illustrate the benefits of the technology. Without it, you would not see this type of overprint problem until the proofing or final output stage, where mistakes can be expensive. For on-screen viewing, Overprint Preview is an excellent way to simulate print conditions on screen. But what about printing? Simulating Overprint for Composite Output Even if you only have a basic color printer on your desktop, you can simulate the same overprint conditions when printing from Acrobat. In the Advanced menu of the Acrobat Print dialog, there is a checkbox to "Apply Overprint Preview." This option will use composite colors to simulate the appearance of overprinting and spot colors. Note that this feature will convert spot colors to process colors in order to simulate them in a composite environment. If you're working on a PostScript 3 device, process-to-process color overprinting is also supported natively, so if it seems like this check box doesn't do anything, this might be the reason. Acrobat can be extremely valuable in uncovering some of the issues that people build into PDF documents. A simple feature like Overprint Preview can save you time and money without making any type of demands on your production workflow. What's more, Adobe InDesign and Adobe Illustrator also support Overprint Preview, so you can be sure that when you're creating your content for print output, you can get it right the first time. Gray Knowlton is product manager of Adobe Acrobat for Creative Professionals.

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