(v13) DeviceLink ICC profiles

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

DeviceLink ICC profiles have proved useful in the graphic arts. A DeviceLink profile encapsulates one rendering intent from one ICC source/destination profile pair. They are popular because they can provide superior fidelity due to the gamuts of both the source and destination profiles being available at the time the DeviceLink profile was created. One popular feature built-in to many DeviceLink profiles is the preservation of the black channel when CMYK is transformed to CMYK. This is not possible in a standard transform using source and destination profiles due to the 4-3-4 channel conversions.

There are also significant disadvantages to using DeviceLink profiles verses standard source/destination profile pairs:

They only apply to a particular pair of source and destination profiles which restricts their applicability.
They contain only one of the three unique rendering intents normally available in an ICC output profile.

In the RIP, DeviceLink profiles may be used as though they were source profiles. They may also be used in an emulation workflow by setting an /InputColorSpace profile. This example emulation configuration, illustrated in Figure: Proofing with DeviceLink profiles, shows both usages:

CODE

<<
	/DeviceCMYK [ /ICCBased (iccprofiles/SWOP-Newsprint.icc) (r) file ]
	/DeviceRGB [ /ICCBased (iccprofiles/sRGB-Newsprint.icc) (r) file ]
	/BlendCMYK [ /ICCBased (iccprofiles/SWOP.icc) (r) file ]
	/BlendRGB [ /ICCBased (iccprofiles/sRGB.icc) (r) file ]
>> setinterceptcolorspace
<<
	/Profile (iccprofiles/Newsprint.icc) (r) file
	/NextDevice <<
		/InputColorSpace
			[ /ICCBased (iccprofiles/Newsprint-Inkjet.icc) (r) file ]
	>>
>> setreproduction

All /DeviceCMYK and /DeviceGray colors are first to be converted to the emulation color space using SWOP-Newsprint.icc. They are then converted to the output device using Newsprint-Inkjet.icc. Similarly, /DeviceRGB colors use the sRGB-Newsprint.icc and Newsprint-Inkjet.icc DeviceLink profiles.

There is no need to set the /IntentMappings in the /NextDevice dictionary as was done in the emulation example Simple interception of device color spaces, because a DeviceLink profile only has the one rendering intent.

Normally the source profile of a transform is taken to be the destination profile from the previous transform in the configuration, but /InputColorSpace can be useful for special effects (that is, /InputColorSpace should not be set unless a DeviceLink or special effect is required).

There are some important restrictions on the use of DeviceLink profiles when used with jobs containing transparency, see (v13) Blend space color management. It is, therefore, normal to use /BlendCMYK and/or /BlendRGB keys in conjunction with DeviceLink profiles, as has been done here using profiles corresponding to the input side of the DeviceLink profiles.

Figure: Proofing with DeviceLink profiles.