HVD External mode
This page applies to Harlequin v13.1r0 and later; and to Harlequin Core but not Harlequin MultiRIP.
To turn on the HVD external mode optimization, use the following PostScript language fragment:
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/EnableOptimizedPDFScan /Always
/OptimizedPDFScanLimitPercent 25
/OptimizedPDFExternal true
/OptimizedPDFCacheID (OEM_HHR_PDF_HVD)
/OptimizedPDFPositionIndependent true
/OptimizedPDFGridEpsilon 1
/OptimizedPDFIgnorePatternPhase true
>> setpdfparams/OptimizedPDFScanLimitPercent indicates the percentage of the job that you wish to scan before deciding whether to continue with HVD.
OEM_HHR_PDF_HVD is the HVD backend to be used to perform raster element caching.
/OptimizedPDFPositionIndependent (default true) should be set to true for maximum reuse, or to false if you're confident that the job does not contain any content capable of being reused at a different position. If in doubt, it is better to set this to true, however if the job really does not contain any content capable of being reused at a different position, a value of false may sometimes result in additional reuse.
/OptimizedPDFGridEpsilon (default 0.000001) should be set to 1 for maximum reuse. When using HVD, the output may have very slight differences from what it would have been without HVD. Setting a smaller value reduces the number of such differences, but reuse is usually significantly reduced.
/OptimizedPDFIgnorePatternPhase (default false) should be set to true to maximize reuse or to false to ensure that pattern phase matches what it would have been without HVD.
When recomposing raster elements, it is usual to mask them. In HVD external mode, configure ContoneMask as follows:
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/ContoneMask -1
>> setpagedeviceA negative value indicates masking should be done by the RIP only when external HVD is being applied to the current set of pages (in which case the absolute value is used). See also ContoneMask (page device)
The LIBTIFF, FRAMETIFF, and the example raster backends HVDNONE and HVDRAW support HVD external mode.