Adobe InDesign supports the Open Prepress Interface, which creates a page-layout workflow that substitutes low-resolution proxies for high-resolution bitmaps. A special server hosts both full-resolution documents and their proxies. At print time, OPI automatically replaces each proxy with its high-resolution image. This workflow helps minimize the amount of information that must flow through a network hosting multiple designers who use large numbers of images. It also limits data-storage requirements on designers' local hard drives.
How It Works
OPI relies on a three-part workflow set up around a server that hosts producers and consumers. A producer application creates layouts that include OPI comments: PostScript language commands that identify high-resolution documents and the proxy images they replace. Prepress software serves as an OPI consumer, reading the OPI comments from proxy images and swapping full-resolution graphics for low-resolution placeholders. An image substitution server provides both low- and full-resolution files through a network as an OPI host. In an OPI workflow, Adobe InDesign can function as both an OPI producer and an OPI consumer.
When It Works
An InDesign graphic-arts workflow typically invokes OPI functions when a layout or page goes through one of a number of potential printing processes. During all prepress phases of design, typesetting and layout, designers work with proxy images in Adobe InDesign, creating a layout destined for one of these output processes. These processes may put ink or toner on paper, create film or plated output for a printing press, or build the document equivalent of either of these options in an Adobe Acrobat PDF file or PostScript output file.
InDesign and OPI Import
When you create an InDesign layout in an OPI workflow, you import images tagged with OPI comments. These images may include PDF, TIFF or EPS files created in Adobe Photoshop or Adobe Illustrator. You set your InDesign import options to read the OPI links embedded in the files you place into your layout. These comments identify the full-resolution file that will substitute for each proxy at print time. You can maintain proxies throughout your design work or use Adobe InDesign as an OPI consumer to replace the proxies before you commit your work to PostScript output.
InDesign and OPI Output
If you create proxy-based layouts for OPI workflows, verify that you send OPI comments along when you print or create output files. Without these comments, the OPI workflow can't make image substitutions and the printed output fails to include them. You must choose OPI-compliant preferences in the InDesign Print dialog box to assure that your output includes the right information for image replacement at the server. If you create a PDF document for review, you can maintain your proxies to minimize document data size, creating a file suitable for email-based distribution or quick download from a document server.