CMY COLOR MODEL

                                      A color model defined with the first colors cyan, magenta, and yellow (CMY) is beneficial for describing color output to hard-copy devices. Unlike video monitors, which produce a color pattern by combining light from the screen phosphors, hardcopy devices like plotters produce a color picture by coating a paper with color pigments. We see the colours by reflected light, a subtractive process.

As we've noted, cyan are often formed by adding green and blue light. Therefore, when white light is reflected from cyan-colored ink, the reflected light MI must don't have any red component. That is, red light is absorbed, or subtracted, by the ink. Similarly, magenta ink subtracts the green component from incident light, Magenta and yellow subtracts the blue component. A unit cube representation for the CMY model.

In the CMY model, point (1, 1, 1) represents black, because all components of the incident light are subtracted. The origin represents white light. Equal amounts of every of the first colors produce grays, along the most diagonal of the cube. a mixture of cyan and magenta ink produces blue light, because the red and green components of the incident light are absorbed. Other color combinations are obtained by an analogous subtractive process.

The writing often used with the CMY model generates a color point with a group of 4 ink dots, somewhat as an RGB monitor uses a group of three phosphor dots. One dot is employed for every of the first colors (cyan, magenta, and yellow), and one dot is black. A black dot is included because the mix of cyan, magenta, and yellow inks typically produce dark gray rather than black. Some plotters produce different color combinations by spraying the ink for the three primary colors over one another and allowing them to combine before they dry.

We can express the conversion from an RGB representation to a CMY representation with the matrix transformation

 


Where the white is represented within the RGB system is that the unit column vector. Similarly, we convert from a CMY color representation to an RGB representation with the matrix transformation

 
 

Where black is represented within the CMY system because the unit column vector.