Override screening system parameters

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

OverrideSpotFunctionName

name or string 
Default: ()

The name or string (they are equivalent) is used as a key to the dictionary switchscreens in $printerdict. Its value is either a spot function procedure or a halftone dictionary. switchscreens should not be modified directly. A zero-length string or name means the parameter is not set and does nothing.

When a new screen is encountered, it is recorded by the RIP in the file sf.ps in the Screens directory of the SW directory. You can then name it directly by editing the file or use the default name allocated to it (which is of the form sfdddddd where d is a digit). Additional spot functions or halftone dictionaries can also be added to this file manually - see Adding extra dot shapes on adding new spot functions.

If OverrideSpotFunctionName identifies a spot function, it will normally be used. The exception is if the job specifies a threshold screen. If OverrideSpotFunctionName identifies a halftone dictionary, some or all of the contents may be used according to a complex set of conditions expressed in the flow charts. It is possible to force some or all aspects of a screen to be used whatever else the job does - including the permanent use of an override screen in place of the job’s screen. Details of controls on halftone dictionaries selected in this way are given in Halftone dictionary keys .

OverrideSpotFunction

integer

Default: -1

This is obsolete and present only for backward compatibility. Use OverrideSpotFunctionName instead. If OverrideSpotFunctionName is not set and OverrideSpotFunction is strictly positive, the number is used to select a spot function according to the index shown in the table in Spot function names.

OverrideFrequency

real

Default: 0.0

A positive (non-zero) value causes the frequency of screens provided by a job to be replaced by the given frequency (in lines per inch). However, OverrideFrequency is only used when there are no other sources of overriding screen, such as a halftone dictionary identified by OverrideSpotFunctionName. The rules for when OverrideFrequency is used are shown in the flow charts.

OverrideAngle

real

Default: -1.0

This is obsolete and present only for backward compatibility. Use the DefaultScreenAngles page device key instead - see Default screen page device keys . If no other override for angles is done, then a non-negative value for this parameter is used as the angle for a screen (in degrees, counterclockwise from the x-axis).