Color spaces and color management

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

In general, the traditional use of the DeviceCMYK color space only works well on devices that are closely matched to the device intended by the designer. Otherwise color management is required to achieve good color. The Harlequin RIP contains a color management system (CMS) that is fully compliant with the requirements of PDF, PostScript, and all supported image file formats. That includes all PDF and PostScript device dependent, ICC, and CIE color spaces. In addition, the RIP’s CMS also contains highly functional extensions. This section describes all the color management features available to the RIP.

Each graphical object in a PDF file will be assigned a color space and a color value, which requires converting to achieve correct color on the output device. The conversion can be modelled, commonly using standard ICC profiles, but also using devicelink ICC profiles, CIE color spaces, named color management, and transforms in C callouts written by the customer, amongst other features. Commonly, this will involve more than one color transform placed in series, which is collectively known as the color pipeline.

Modelling a color pipeline relies on two Harlequin extension operators which are widely used throughout this chapter. The setinterceptcolorspace operator replaces, or intercepts device spaces, e.g. with an ICC profile, which controls how color spaces in a PDF file should be handled; while setreproduction configures how to convert the resulting color to the output devivce. There are many examples in this section, including illustrations, of color pipelines containing one or multiple transforms.

In general, PDF files containing transparency require color conversions between transparency groups with different blend spaces. Commonly, the blend spaces are device spaces, e.g. DeviceRGB. The RIP supports color management of these transforms, but is more limited in what is allowed since it is only the setinterceptcolorspace operator that controls transforms between transparency blend spaces. These features are exxplained further in Transparency color management and espcially Blend space color management.

To make use of the setreproduction operator, you must have Harlequin ColorPro installed and activated.

Harlequin color management is designed to make ICC workflows easy to model, while at the same time providing a highly functional and flexible CMS that can be configured for any known color workflow.

While this section is the reference for Harlequin color, it has been written as partly a tutorial with many examples throughout.

A number of example page features are provided as part of the Harlequin Core SDK to illustrate various aspects of color management for CMYK, RGB and extended gamut colorant sets.