Learn the basics of creating PDF files.
Composite files are smaller and can be viewed by the user before they are sent to the RIP. They contain all the necessary information to separate and print the job. This includes UCR/GCR, trapping, OPI comments, halftone line count, angles, paper size, and solid spot color information. All of this information goes to the RIP where the file is rasterized and printed to the imagesetter or digital color printer.
Drawbacks to PDF
The limitations of working with PDF files include minimal editing and touch-up ability beyond those available in Acrobat Exchange. Complex PDF files are extremely difficult to edit without special plug-ins like Crackerjack. Additionally, because using PDF files for high-resolution printed graphics is a relatively new alternative, few service bureaus are experienced in handling the files.
Working with PDF files is not for the prepress novice. A good working knowledge of the prepress process and how color separations work is essential. As screen printers, we must also be intimately familiar with film preparation and our own printing requirements and limitations.
At this point, successful use of PDF files for output also requires some editing of PostScript code. And remember, PDF files can only be output directly to an imagesetter or digital color printer if you or your service bureau use a PostScript III compatible RIP. Presently, few service bureaus and even fewer screen shops have such RIPs. More details about the nuances of working with PDF files are available on a white paper entitled "Preparing Adobe PDF Files for High-Resolution Printing," which can be accessed at Adobe's Website (www.adobe.com/print/).
The future of PDF
PDF is a very exciting technology, and as its use in graphic arts increases, it's likely that we'll see many more useful plug-ins developed for the Acrobat Suite. It also means that we'll be able to customize how the program works in our own particular workflows. This may mean Hot Folders, where we drag and drop images for automatic conversion, or scripted routines where all the conversion work occurs automatically in the background.
Like any developing technology, PDF will gain strength through use. It is already a mature technology for document display and printing, and a growing favorite for Web use. Its utility for prepress is sure to follow suit.
About the author
Mark A. Coudray is president of Coudray Graphic Technologies, San Luis Obispo, CA. He has served as a director of the Screenprinting and Graphic Imaging Association International (SGIA) and as chairman of the Academy of Screenprinting Technology. Coudray has authored more than 70 papers and articles over the last 20 years, and he received the SGIA's Swormstedt Award in 1992 and 1994. He covers electronic prepress issues bimonthly in Screen Printing magazine. He can be reached via e-mail at email@example.com or firstname.lastname@example.org.
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