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Black Generation:

A big part of output profile generation involves the setting for Black using a processes called Under Color Removal (UCR) and Gray Component Replacement (GCR). Each printing ink controls one third of the spectrum: cyan controls red, magenta controls green, and yellow controls blue. It is possible to reproduce all colors using only cyan, magenta, and yellow ink. The forth color in printing is black and though we don’t have to use it, in theory, it is used for colorimetric and commercial advantages. We can create the same color using a lot of cyan, magenta and yellow, and just a little black. Or, we can use a little cyan, magenta, and yellow, with a lot of black. Since black is not needed, its use is redundant. The GCR/UCR process is used to reduce the process colors of cyan, magenta, and yellow, and replaces them with an equal amount of black ink.

There are several advantages to this:

  1. Too much ink can cause problems with a printing press. Black ink reduces the overall ink coverage, which in turn helps with drying problems and in printing on paper such as newsprint.
  2. Using less amounts of process colors makes printing presses more stable because there is a lower level of colorants, which minimizes their efforts if they may vary slightly.
  3. Black ink is less expensive to use than colored inks.
  4. The addition of black ink extends the density in the shadows, providing deeper blacks.
  5. Using black ink provides crisper, cleaner, and more neutral blacks than mixing cyan, magenta, and yellow.

How to use GCR and UCR methods:

Step 1:  Using Adobe Photoshop, Choose Edit > Color Settings, to bring up the Color Settings Dialog Box

Step 2:  Under the Working Spaces box choose CMYK and scroll to the top to choose Custom CMYK.  The Custom CMYK Dialog Box should appear.

Step 3:  In the Ink Colors section we chose SWOP (Coated).  Dot gain should be set at standard with 20%.  The Separations Options section contains GCR and UCR methods.  When GCR is chosen you have the option of choosing Black Generation of None, Light, Medium, Heavy, and Maximum.  When UCR is chosen the option of Black Generation is not used. 

Step 4:  Make sure that Total Ink Limit stays at 300% and UCA Amount is 0%.  Press OK.

Step 5:  Name the new custom profile according to the parameters that you have just set by selecting SAVE in the Color Settings Dialogue Box.

Step 6:  Choose Edit > Convert to Profile.

Step 7:  Make sure that the Destination Space Profile is the one you made for GCR or UCR method.  Click on the Settings drop down list to choose the profile you just created.  Press OK.

Original original heavy_small Heavy
Light light_small maximum_small Maximum
Medium medium none_small None