The CMY and CMYK color space

Devices like color printers and copiers that deposit color pigments on paper use a color model that is based on the cyan, magenta and yellow colors. This color model is called CMY and to convert a color from RGB to CMY simply use the following formula:

[C]    [1]   [R]

[M]= [1]- [G]

[Y]    [1]  [B]

The above formula shows that when a cyan colored paper is illuminated with while light it will not reflect any red light and therefore extracts red from the white light. therefore this color model is sometimes called subtractive color model.

As with the RGB color model every color is represented by three values C, M and Y and these values are assumed to be in the [0,1] or [0, 255] range.

The CMYK color model is mostly used by printers that have a separate black color ribbon or ink available. The CMYK color model is very similar to the CMY color space, but has a fourth component K that represents black color. The black component is also assumed to be in the [0, 1] or [0, 255] range.

To convert from CMY to CMYK, use the following formula:

K = min(C, M, Y)

C = C K

M = M K

Y = Y - K

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