What does the 'K' stand for in CMYK color model?

In the CMYK color model, the 'K' stands for 'Key.' This terminology is used to represent the black ink or the black component in the color model. The CMYK model itself is a subtractive color model employed in color printing, where 'C' stands for cyan, 'M' for magenta, 'Y' for yellow, and 'K' serves as the key or black component that enhances the depth and detail in printed images. The use of black in addition to the other colors allows for a greater range of color depth and contrast, as well as more efficient printing processes since using a true black ink can reduce costs and improve print quality.

In this context, the other terms—color, calibration, and kernel—do not accurately represent the ‘K’ in CMYK, focusing on aspects unrelated to the specific role that black plays in the color printing process.