Right: Photoshop's Channels palette shows how an image is composed in RGB or CMYK mode. On the right are the four channels of CMYK, which appear very much like the proofs taken from each lithographic printing plate. The channels displaying RGB are instantly recognizable by the areas of black in each channel which represent the absence of light. Note that the top images in these palettes are not channels themselves but provide a view of the combined channels.
two primaries as pigments(making them of the part reflective surface rather than transmitted light) will result in colour being absorbed.