Default screen page device keys

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

Four page device keys control the default behavior of screening: DefaultScreenAngle (now obsolete), DefaultScreenAngles (its replacement), DefaultScreenFrequency, and DefaultScreenName. If these keys were not available, it would be necessary to write an Install procedure to set up the default screen, so they provide some automation.

The DefaultScreenAngles page device key also provides a method of specifying whether the default angles should override any other angles set by the job.

For example:

TEXT

            <<
              /DefaultScreenName (Euclidean) cvn
              /DefaultScreenFrequency 56.0
              /DefaultScreenAngles <<
                /Cyan <<
                  /Angle 15.0
                  /Override true
                >>
                /Magenta <<
                  /Angle 75.0
                  /Override true
                >>
                /Yellow <<
                  /Angle 0.0
                  /Override true
                >>
                /Black <<
                  /Angle 45.0
                  /Override true
                >>
                /Default <<
                  /Angle 45.0
                  /Override true
                >>
              >>
            >> setpagedevice

DefaultScreenName

name

Default: null

If not null, during execution of setpagedevice sets the current spot function to be the screen named, and otherwise Euclidean, as defined by switchscreens in $printerdict.

OverrideSpotFunctionName (or OverrideSpotFunction) may then override this setting, though typically they would be the same; that is certainly the case for GUI versions of the RIP.

DefaultScreenFrequency

real

Default: null

During execution of setpagedevice, sets the frequency of the current screen to the number given in lines per inch (lpi), or 45.0 lpi if null. OverrideFrequency may then override this setting, though typically they are the same.

DefaultScreenAngles

dictionary

Default: null

Providing DefaultScreenAngle is null, DefaultScreenAngles sets the angles of screens for all colorants to those specified in the dictionary.

Each entry in the dictionary is keyed by colorant (in the manner of a type 5 halftone), and each value is also a dictionary. There must also be an entry Default which determines the angle for any colorant not explicitly named (again, as for sethalftone).

Each colorant dictionary contains two (required) keys:

Angle, the angle for the screen for that colorant (as a real number of degrees, as in the angle operand to setscreen)
Override, a Boolean which if true causes the angle to override any set by the job for this colorant. This replaces the system parameter OverrideAngle, which was only appropriate for a single colorant. Typically, either all or none of the angles would be overridden, though DefaultScreenAngles allows them to be controlled independently. (The GUI controls act on all angles together. The control is the Override angles in job checkbox in the Edit Style dialog box, accessed from the Separations Manager.)

If both DefaultScreenAngles and DefaultScreenAngle are null, the default angle is set to 45.0 for all colorants.

DefaultScreenAngle

real

Default: null

Obsolete and included only for backward compatibility; use DefaultScreenAngles instead. During execution of setpagedevice, sets the angle of all screens to the given number. If null, the parameter is ignored.

Please do not confuse this with DefaultScreenAngle in addtoseparationorder.