Why Does My Pure Black Print Out as CMY?

Why Does My Pure Black Print Out as CMY?

I recently had a customer call me in because he was puzzling over an unusual color problem - His print file specified pure K at over 95%, but the color management engine kept printing the file in CMY, and he could not determine why. It shared space with other color images, and their color specs had not changed at all, only the black image.

After some testing - OK, it was four and half hours of testing - we determined that it was the GCR causing the issue.

For those of you just joining the conversation, GCR is Gray Component Replacement. We discussed it previously HERE. You can also find it in the GLOSSARY.

Normally, we think of GCR replacing the CMY components of an image with more K to minimize the ink or toner usage. But under certain circumstances the GCR component of your RIP can actually add CMY to pure black if it determines that black alone cannot accurately reproduce the color relative to its original colorspace.

The certain circumstances are these: You ARE set to Full GCR (whether source or output directed) and you do NOT set your gray setting to include Text/Graphics/Images.

This can also be overcome by using pure primaries, which effectively turns GCR off.

RIP manufacturers have confirmed this is how the RIP is supposed to function, so this is not a bug, just a particular parameter setting that created a condition noticed only because were looking for it.

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Do you have a color management question, horror story or event to share?

Email me at reilley4color@gmail.com