(v13) Transfer functions and halftones
This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP.
Some halftone dictionaries can have a TransferFunction
entry. [RB2] says that TransferFunction
“overrides the transfer function specified by settransfer
or setcolortransfer
”. Likewise, [PDF2] says it "shall override the corresponding one specified by the current transfer function parameter in the graphics state". However, the RIP applies both by default. There is a user parameter UseAllSetTransfer
to provide for strict compatibility (see (v13) Order of application of calibration and transfer functions); however, we believe that because jobs use settransfer
and setcolortransfer
it is not reasonable to suppress this just because a halftone is set with a TransferFunction
entry, and that unintended effects could be caused by direct application of the manual’s definition.
Also, the TransferFunction
entry in halftone dictionaries has been extended. As well as the standard types, a literal array or a dictionary can also be given. Literal arrays are interpreted as interpolation arrays (see (v13) Calibration interpolation arrays).
Dictionaries represent PS functions.