Color images are commonly printed with cyan, magenta, yellow, and black (CMYK) inks rendered as halftone images and printed in register with each other. Although this process is known as four-color printing, the black ink is not technically a color because it does not have an associated hue (or dominant wavelength). The addition of black in a three-color printing system extends the range of printable tones and improves detail rendition in the shadow region.