Many of you must have read these terms ‘RGB’ and ‘CMYK’ in my previous post, and wondering just what they are.
Well, RGB and CMYK are 2 models of representing color. Typically, RGB model is used in web and screen colors, while CMYK is almost exclusively used in print medium.
The following graphics show the color models in their representative form.
The abbreviation RGB stands for Red-Green-Blue. Every color pixel that we see on a computer / TV screen is a combination of various quantities of these three primary colors. When these three colors are mixed at their full strength, the color white is produced. That’s why, sometime these colors are called ‘Additive colors’.
Printing is a different ball game, though. When priniting on paper, the printers use inks of CMYK combination. CMYK stands for Cyan-Magenta-Yellow-Key. Cyan, Magenta and Yellow are the three ‘Subtractive Colors’ i.e. adding them together yields black color.
Every color printed on paper is a combination of CMY colors in various quantities. The ‘K’ in ‘CMYK’ stands for Key, which is a term used for black color. The reason the letter ‘B’ is not used for black is to avoid confusion with Blue in the term ‘RGB’.
Black color is separately mixed along with CMY combination while printing. Even though combining CMY colors yields black, it may not be a very neat effect due to impurities in inks, and any discrepancy on a black print is easily visible on paper. That’s why black is treated as a separate color and printed so.
The reason CMYK combination is used for printing on paper is why sometimes paper printing in color is sometimes referred to as ‘Four color printing’.
Sometimes, there’s a need to use a special color in very precise quantities while printing. This is achieved by adding the ink for that special color to the printing process. This is called ‘Spot Coloring’.
The color spectrum within CMYK world is not as rich and diverse as that of RGB. That’s why it’s quite possible that an image appearing brightly colored on screen may not be reproduced as it is on paper (on professional printers). The inkjet and laser printers may produce this RGB effect accurately, but the professional offset printers will not.