Historia

T

hese days there’s a new workflow in modern print shops. Print professionals are trying to get their digital proofs to match the press, instead of matching the press to the proofs. They’re doingthis because it’s easy to make a proof — especially a film-based analog proof — that contains colors which can’t be achieved on press.

blues are all thrown off. The same type of compromise occurswhen steering color on the press. What’s needed is a way to take yellow out of reds without affecting greens, grays and/or pure-yellow vignettes.

ICC-based color management
The solution is to useICC-based color management, which works by instantly transforming a source CMYK to a new, color corrected CMYK — say from press CMYK to proofer CMYK , dynamically, automatically simulating the pressbehavior (even non-linear wet trap) on the proofer. This process works well, but there is a hidden danger in the typical color management workflow. Normal ICCbased color management uses a “deviceindependent connection space” called LAB to connect one profiled device to another. Because the CMYK to CMYK color management transformation runs through LAB, which discards all original source CMYKinformation, all elements in a file actually completely re-separate — including the individual pure-color channels. As a result, ramps of pure yellow usually end up with a cyan scum dot, cyan acquires amagenta scum dot and magenta gets a cyan dot. Worst of all, black-only elements, such as text and blends, completely re-separate to four-color black. If you are selling a customer a $200 dot-proof, youreally don’t want to have to explain why what’s supposed to be pure yellow has cyan dots.

Here’s why
Often, the hues of the CMYK inks used in proofing systems don’t match the press inks. This alonecan make color matching problematic. Also, the dot gain characteristics of a given proofer and printing press are usually different. But often the biggest cause of color matching problems is “wet...