(v13) Default compositing profiles

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

When a device independent color space is composited into a transparency group with a device blend space, for example; /DeviceRGB, the PDF specification does not define a color conversion. In the RIP, these are the rules that are applied to determine the action to take:

• if there is an intercept for the blend space, use it as the destination profile
• otherwise, if compositing an object directly into the virtual device when OverprintPreview is inactive, use the current CRD from the gstate. Using the CRD is consistent with the PostScript language. There is just one CRD in the gstate. The default CRD is similar to sRGB.
• otherwise, use the appropriate default ICC profile for the blend space. The RIP has a default ICC profile for each of the /DeviceCMYK, /DeviceRGB, and /DeviceGray blend spaces. The reason for using the default profile is that results are generally more pleasing than using the default CRD. The reason being that there is only one CRD, and the output of this would otherwise have to be converted to the actual blend space using device conversions, often with unexpected results.

Jobs that contain mixtures of device independent and device dependent color without using color management often produce unexpected results. It is recommended that color management be used rather than relying on the default profiles.