CcMmYK color model

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An image printed with a CcMmYKk ink set, on both paper and canvas stock. The ink cartridges used are also shown.

CcMmYK, sometimes referred to as CMYKLcLm, is a six color printing process used in some inkjet printers optimized for photo printing. It extends the customary four color CMYK process, which stands for Cyan, Magenta, Yellow and Key (black), by adding light cyan (lower case c) and light magenta (lower case m). The light cyan and light magenta inks are essentially a washed out version of the cyan and magenta inks.

Individually, light cyan is often abbreviated to Lc, and light magenta is represented as Lm.

Advantages of CcMmYK over CMYK

The most noticeable result of using light cyan and light magenta inks is the removal of a distinct and harsh halftoning dot appearance that appears in prints that use light shades of cyan or magenta on the pure CMYK ink configuration. Usually when printing a dark color the printer will saturate the area with colored ink dots, but will use fewer ink dots to create the effect of a light color. The result is hard to notice with Yellow because the human retina is not as sensitive to yellow as other colors. However, the individual cyan and magenta ink dots will stand out in a sparse pattern due to their darker color against a white background; the result is undesirable when it is noticed.

By using light cyan or magenta, the printer can saturate areas that would typically use halftoning with these inks to remove the look of sparse magenta and cyan dots. The downside is the printer needs approximately twice as much light cyan/magenta ink in areas to achieve the same saturation as pure cyan/magenta which can lead to excess ink usage. The end result, however, is significantly better for some photos.