(v13) PDF/X Color Management
This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP
One distinguishing feature of PDF/X is that all color transforms within the job are required to use ICC transforms using a source/destination profile pair. The ICC profiles are provided in ICCBased color spaces, tagged device spaces, DestOutputProfile from the OutputIntents object, or DestOutputProfileRef (for PDF/X-4p and PDF/X-5pg only).
Of the various supported types of PDF/X, PDF/X-1a files never have their color management settings modified when the RIP is in PDF/X mode. (The output intent in a PDF/X-1a file is assumed to be included to enable preflight and for emulation on devices with different behavior from the print characterization referenced, rather than for direct use in rendering.) All other valid PDF/X files will be printed with modified color management described here.
The required predictability of colors in PDF/X files in the RIP is achieved with these steps:
- setting the initial rendering intent to RelativeColorimetric.
- ignoring any source profiles from the job configuration.
- treating DestOutputProfile as an emulation profile.
- ignoring color management overrides until the final conversion to the output device; after colors have been converted to the DestOutputProfile.
- destination profiles implied by the job configuration are converted to additional color management transforms using the /NextDevice feature of setreproduction as illustrated later.
The color settings that are not affected by the PDF/X mode are these:
- black preservation.
- named color management.
so, these two features will work in PDF/X mode.
After converting colors to the DestOutputProfile emulation profile, the color management overrides are honored. This means that a source profile provided by setinterceptcolorspace is used when converting color from DestOutputProfile to the output device space. The source profile may be a DeviceLink if desired.
As an example of how the color management is modified in PDF/X mode, the simple DeviceLink configuration:
<<
/DeviceCMYK [ /ICCBased (iccprofiles/SWOP-Digital.icc) (r) file ]
/DeviceRGB [ /ICCBased (iccprofiles/sRGB-Digital.icc) (r) file ]
/NamedColor [ /PantoneCoated /PantoneUncoated
/PantonePLUSCoated /PantonePLUSUncoated ]
/Black false
/BlackTint false
>> setinterceptcolorspace
<<
/Profile (iccprofiles/Digital.icc) (r) file
/IntentMappings /Perceptual
>> setreproduction
will be treated as:
null setinterceptcolorspace % To remove all existing intercepts
<< % Replace named color and black preservation
/NamedColor [ /PantoneCoated /PantoneUncoated
/PantonePLUSCoated /PantonePLUSUncoated ]
/Black false
/BlackTint false
>> setinterceptcolorspace
<<
/Profile <DestOutputProfile>
/NextDevice <<
/Profile (iccprofiles/Digital.icc) (r) file
/IntentMappings /Perceptual
>>
>> setreproduction
while the same simple configuration, but with the OverrideCMYK setinterceptcolorspace key set to true, will be treated as:
null setinterceptcolorspace % To remove all existing intercepts
<< % Replace named color and black preservation
/NamedColor [ /PantoneCoated /PantoneUncoated
/PantonePLUSCoated /PantonePLUSUncoated ]
/Black false
/BlackTint false
>> setinterceptcolorspace
<<
/Profile <DestOutputProfile>
/NextDevice <<
/InputColorSpace [ /ICCBased (iccprofiles/SWOP-Digital.icc) (r) file ]
/Profile (iccprofiles/Digital.icc) (r) file
/IntentMappings /Perceptual % Ignored because of the devicelink
>>
>> setreproduction
where the difference is the CMYK DeviceLink profile from the setup is applied after colors have been converted to DestOutputProfile.
Output intents in PDF 2.0 files
The PDF 2.0 standard includes output intents in a very similar way to PDF/X, but without any explanation of exactly how they should be applied. From Harlequin version 12, output intents with GTS_PDFX as the value of their S key will be processed in as close a way to that specified in the various PDF/X standards as possible. Output intents with other values for the S key will be ignored.