To reproduce color and continuous-tone images, printers usually separate artwork into four plates—one plate for each of the cyan (C), yellow (Y), magenta (M), and black (K) portions of the image. When inked with the appropriate color and printed in register with one another, these colors combine to reproduce the original artwork. The process of dividing the image into two or more colors is called color separating, and the films from which the plates are created are called the separations.

Separation workflows

Adobe InDesign CS3 supports two common PostScript workflows; the main difference is where separations are created—at the host computer (the system using InDesign and the printer driver), or at the output device’s RIP (raster image processor). Another alternative is a PDF workflow.

Host-based separations

In the traditional host-based, preseparated workflow, InDesign creates PostScript information for each of the separations required for the document, and sends that information to the output device.

In‑RIP separations

In the newer RIP-based workflow, a new generation of PostScript RIPs performs color separations, trapping, and even color management at the RIP, leaving the host computer free to perform other tasks. This approach takes less time for InDesign to generate the file, and minimizes the amount of data transmitted for any given print job. For example, instead of sending PostScript information for four or more pages to print host-based color separations, InDesign sends the PostScript information for a single composite PostScript file for processing in the RIP.

For a video on preparing files for output, see www.adobe.com/go/vid0089. To view a printing guide for prepress providers (PDF), see www.adobe.com/go/learn_id_prepress_wp.