CMYK

CMYK stands for the four printing inks Cyan, Magenta, Yellow and “Key” (Black) . These four inks are the base of four-color printing. For printing colorful photos at least these four inks are required.

Colour mode

The colour mode is a setting that determines the depth to which colours can be displayed in an image file. This also affects the size of the file.
The most common colour modes are RGB, CMYK, Lab, Index mode, Greyscale and Bitmap.