CMYK refers to the four inks used in color printing and the scheme for combining these primary pigments: cyan, magenta, yellow, and key. The key color in the world of printing is now black which helps limit the amount of other inks needed to create an image. Usually printed on white paper, that reflects light, the four inks are used and subtract that light to create vibrant colors.
Each combination in mixing the four main pigments in the CMYK process has a unique four number sequence. Each of the four numbers range from 0 to 100 and may be considered the percentage of each of the four pigments in the combination. The four primary pigments shown below are 100 in one of the four numbers and 0 in the other three. This four number sequence can be influential in matching existing colors the brand is using and help create color continuity across materials.
Process Cyan C Magenta C Yellow C Black C
100 | 0 | 0 | 0 0 | 100 | 0 | 0 0 | 1 | 100 | 0 0 | 0 | 0 | 100
While the key is not needed, as combining CMY would create a dark color, it is an essential element to this pigment scheme. To create the black without key would require a lot of ink and usually results in a brownish black color which may change the ending result and image. Using the three colors soaks the paper which may cause bleeding (of colors or fonts not reading correctly) or compromise the papers durability. Adding black ink absorbs more light and creates a crisper black and helps differentiate better between dark areas and black areas. Depending on the project, there are a few processes that may be used to ensure the best ending result is achieved. Some of these processes involve removing or adding color or using grey as a replacement in certain aspects of combining the pigments to create the final image.
Most digital generated images utilize a different color scheme called RGB which is an additive color model using red, green, and blue to create an image. In this model, black is created by the absence of light while white through the combination of all colors. Below the two color schemes are shown and may provide a better example of how colors are produced. Because of the difference in how the colors are created, images and colors produced on a computer may not completely match when printed even after converting from RGB to CMYK for printing.
When it comes to graphic design, most designers will print using CMYK with test prints to ensure everything is perceived the way they pictured when designing on the computer. When designing, using the correct color mode can help save time and ensure color is displayed the way the designer and client agreed upon across all platforms and generated content. Hopefully this information will help you better understand the significance of these two color schemes. Design on my friends!