Bold black

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Rich black ( english rich black ) describes a particular type, black in color printing to mix and with the primary colors cyan , magenta and yellow to enrich. In order to obtain a particularly bold, powerful and opaque deep black, the option of CMYK color structure is used instead of just displaying the black with the K channel .

Color mixing

Black in the CMYK color model is created when the four basic colors cyan, magenta, yellow and black are physically mixed with one another. Black made from 100% K (Key = Keycolor) often does not achieve the desired color coverage, but rather looks dull. For this reason, the CMY channels are mixed in in a certain ratio. The higher the ink application, the higher the color density of the inks on the print medium, and thus a richer color tone is achieved.

Jet black in four-color printing

The color structure of deep black in four-color printing is very complex and cannot be dealt with with a defined color value. The mixing ratio of cyan, magenta, yellow and black depends on many factors:

  • The choice of the printing process has an influence on the bold black, because the ink compositions and pigments can differ greatly.
  • The printing medium accepts printing ink very differently. Accordingly, the same motif can appear flatter and lighter on a matt material, whereas the printing ink looks stronger and darker on a glossy print medium.
  • Texts, thin lines, other delicate and thin graphic elements can be printed with a bold black, but depending on the printing process, register problems and color flashes can occur.
  • The maximum paint application of 280% should not be exceeded.

Optimal black

For an optimal black tone, all four process colors usually have to be mixed. When choosing the exact composition, depending on the respective printing process, stenciling effects , ink acceptance and the delay must be taken into account. General values ​​can only be viewed as a first point of reference.

variants

The Fogra Forschungsgesellschaft Druck eV sees z. B. in their color tables for printing processes according to ISO 12647-2 : 2004 in paper class 1, a total of 32 different mixtures of 100% key with the three other colors of the CMYK color model . Depending on the strength of the undercolor reduction or the achromatic build-up, different such black tones result from the separation of digitized image data, which is also referred to as under color addition (UCA). A special case in which all the basic colors used in the color model are used 100% is the pass color of the registration mark .

See also

Individual evidence

  1. ↑ Janine Salier: Do you know how black and deep black are created correctly in CMYK? salierdruck.de/blog, June 27, 2016, accessed on July 11, 2016 .
  2. ^ Fogra Forschungsgesellschaft Druck eV . Retrieved September 12, 2012.
  3. ↑ FOGRA39 . Fogra Forschungsgesellschaft Druck eV. August 24, 2005. Retrieved March 7, 2011.