What is Preflight in Desktop Publishing?

The process of preflighting a file helps reduce the likelihood of rasterization problems that cause production delays. Page layout software applications, (which allow users to combine images, graphics, and text from a variety of formats,) automate portions of the preflight process. Typically, client provided materials are verified by a preflight operator for completeness and to confirm the incoming materials meet the production requirements. The pre-flight process checks for:

• images and graphics embedded by the client have been provided and are available to the application
• fonts are accessible to the system
• fonts are not corrupt
• fonts are in a compatible file format
• image files are of formats that the application can process
• image files are of the correct color format (some RIPs have problems processing RGB images, for example)
• image files are of the correct resolution
• required color profiles are included
• image files are not corrupt
• confirm that the page layout document size, margins, bleeds, marks and page information all fit within the constraints of the output device and match the client specifications
• confirm that the correct colour separations or ink plates are being output

Other, more advanced preflight steps might also include:

• removing non-printing data, such as non-printing objects, hidden objects, objects outside the printable area and objects on layers below
• flattening transparent objects into a single opaque object
• converting fonts to paths
• gathering embedded image and graphic files to one location accessible to the system
• compressing files into an archive format

The specifics of what checks are made is governed by the features of the preflight application, the formats of the client provided files, and the targeted output device as well as the printing specifications.