Subtractive mixture or subtractive color mixture is the phenomenon in which lightness is reduced with the mix of object colors.
Color can be divided into light source color, which is the color of the light itself, and object color, which is the color produced when light hits an object and is reflected, absorbed or transmitted. Object color refers to the color of an object which does not emit light itself and can be represented by the mixing ratio of the three primary colors: cyan, magenta and yellow.
The object color of paint, ink and filters, etc. has the characteristic of absorbing light. This results in a drop in transmittance to produce dark colors. When mixed in equal amounts, they become black (achromatic color). Hues also change as seen in the fact that when magenta and yellow overlap, they produce red. With color printing, it is not possible to fully reproduce black using the three primary colors.
Therefore, all colors are reproduced by combining cyan, magenta and yellow (CMY) with black (K for key plate). The opposite of subtractive color mixture is additive color mixture, which results in greater lightness.