OPI (Open Prepress Interface)

This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP.

OPI stands for Open Prepress Interface and was originally specified by Aldus Corporation. (See [OPI2.0] and [OPI1.3] for details.) OPI specifies a set of PostScript-language comments that identify images in a PostScript-language job and the characteristics and location of files containing alternative images, usually at higher resolution, which can be substituted. Similarly. PDF jobs may include OPI dictionaries in image and form objects to identify alternatives.

Version 6.x and later support both of the standards defined by [OPI2.0] and [OPI1.3]. It is possible to switch on or off support for either or both versions, and to determine which version of comments should be used if comments for both versions are found in a PostScript file associated as described in the OPI 2.0 specification. This is controlled by setting OPIversions.

The intention was that a preprocessor would locate the comments, strip out the low-resolution image, insert the high-resolution image, and pass the result to a PostScript-language compatible interpreter. However, the comments can be processed by the comment parsing mechanism and therefore the image can be directly stripped in as the PostScript-language file is being interpreted.

The HqnOPI procset implements OPI processing (and also DCS processing as described in DCS (Desktop color separation) ). In versions of the Harlequin RIP where HqnOPI exists in the SW/procsets directory, this procset can be used immediately. The procset is suitable for production use, subject to the notes given under Limitations of OPI replacement.