Deciding which screen properties to use

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

The RIP provides a wide range of parameters to control how different aspects of a screen are selected for use in a job. Used appropriately, these parameters can have an effect that ranges from using the contents of a specific halftone dictionary - whatever the job, GUI, or page device may say - through to using exactly what the job specifies.

Many applications or printer drivers allow the screen frequencies, angles, and sometimes spot functions to be specified in the Print dialog, or somewhere similar. The values given are not always appropriate, for example because it was not originally envisaged that a particular output device would be used (maybe the same job that was used as a draft on a laser printer is sent directly to the prepress bureau), or used at the final resolution actually chosen; or part of the job was imported and used different screens; or simply because the user did not understand the dialog or the implications of choosing a particular screen. Using a consistent set of screens gives uniformity to prepress results making the printing more controllable and predictable.

Also, there are efficiency advantages to using consistent sets of frequencies, angles, and spot functions, especially when using HPS. Versions of the RIP which can write to a disk cache screening data on disk. (Most versions can do so, though core-RIP customers may choose not to include a disk). This means that when the same screen is encountered again in another job, it is very quick to prepare the tables required to render the screen. Even when the cache does not exist, the spot functions on the RIP’s list are more efficiently processed because the functions are "compiled".