Page 124 - Graphic Design and Print Production Fundamentals

112 Chapter 4. Colour Management in the Graphic Technologies
• Scan as high-bit tiff

• Open in Photoshop (beware of any automated conversions or profile assignments) to rotate,
crop, and spot

Comparatively, for the digital camera:

• Light evenly

• Capture square
• Open in Photoshop (beware of any automated conversions or profile assignments) to rotate,
crop, and spot

With the digital image in hand, we’re ready for the input profile creation. Measure the commercial target
with the spectro if you are not using a supplied target description file. Launch your colour management
software and you will be prompted to identify the target image and the corresponding target description
file. The profiling software reads the RGB values from the scanned or captured image, and the software
processes the target description file and RGB measurement file to produce the input profile. File-saving
options are very similar to what we have previous described for output and display profiles.

Device Link Profiles

Device link profiles are most closely related to the output class of profiles. A device link profile
combines two output profiles to provide the specific conversion instructions between two particular
devices. It provides the opportunity to maintain black and other separation purity (i.e., what begins as
black only in the source colour space emerges as black only in the destination colour space) by removing
the need for passing the colour transformation through the PCS. To define a device link, we identify
a source and destination profile to our colour management software, specify the rendering intent, and
provide details on how constrained the re-separation should be. By avoiding the passage into and back
out of the PCS, we can very strictly control the parameters of the colour conversion. The options for
conversion are:

• Full re-separation — Complete re-separation. Solid colours in the original file may not
remain solid. The black generation parameters that you specify are used, which may result in
using less chromatic ink and more black ink.

• CMYK integrity — All colour builds can be adjusted. The relative amount of black versus
CMY will be preserved in content processed through the device link.
• Black purity only — Any colours other than the black channel (solid K, K-greys) can be
adjusted.

• Colour and black purity — The same as fully constrained, but solid colours can be reduced to
a tint.

• Fully constrained — Any colour made with only one or two inks will not have other inks
added. Solid (100% tints) primaries and secondaries are not affected and remain solid.
• Ink optimizing — A proprietary term in the ColorFlow colour management software for
applying a full re-separation with a heavy grey component replacement (GCR) algorithm.