(v13) Transparency mode

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

Transparency mode is a generalization of CMYK Overprint mode in that the VirtualDeviceSpace may instead be RGB or Gray. They have been split into separate modes because the requirement for colorimetric CMYK overprints is generally separate from the requirement for color managed transparency compositing.

A good reason for setting the VirtualDeviceSpace to RGB or Gray is if a PDF job contains transparency effects, but does not have a page group color space. Setting OverprintPreview along with a VirtualDeviceSpace will emulate the effects of the job containing a suitable page group.

In this mode, objects are rendered into the virtual device with these properties:

• the color model is one of CMYK, RGB, or Gray, depending on the VirtualDeviceSpace, (see (v13) PDF/X Initial Settings ).
• the virtual device is tagged with the appropriate intercept profile from setinterceptcolorspace.

Here, the virtual device is emulating a real device that:

• was characterized with the intercept profile for VirtualDeviceSpace, and
• can render the spots without conversion to the alternate space.

The virtual device internally renders overprints and compositing without including any of the effects of setreproduction or calibration, which are applied in the conversion of all colors from the virtual device to the output device. The result is good compositing of objects placed directly on the page, and a simulation of spot overprints.

If the job contains color spaces other than the VirtualDeviceSpace, the blend space color management (see (v13) Blend space color management ), will be applied the same as for transparency jobs. The quality of the output depends partly on the quality of the ICC profiles used in the configuration, and on the size of the color gamuts in the various profiles. Whether or not this is undesirable can only be determined by testing.

In this mode:

• transparency objects painted directly on the page are composited in the correct blend space.
• the treatment of spots is identical to the SpotsOnly mode.
• all other color spaces will be converted into the appropriate intercept profile for the virtual device, leading to an extra color transform which may not be desirable.

The Transparency mode of OverprintPreview is activated using the setinterceptcolorspace operator, in this example using an RGB virtual device:

<< /OverprintPreview true >> setinterceptcolorspace

<< /VirtualDeviceSpace /DeviceRGB >> setpagedevice

VirtualDeviceSpace

This is the color model of the implicit transparency page group, or virtual device, that is used when OverprintPreview is active. The VirtualDeviceSpace setting does not have any effect when OverprintPreview is inactive.

The allowed values are /DeviceCMYK, /DeviceRGB, and /DeviceGray. The default is /DeviceCMYK. It is set using the setpagedevice operator, for example:

<< /VirtualDeviceSpace /DeviceRGB >> setpagedevice