RGB Colors vs CMYK Colors
RGB and CMYK are two different methods for generating colors.
RGB stands for Red, Green and Blue. Combining these three colors will produce a whole range of different colors. The colors you see on your computer monitor are RGB colors, as are the colors produced by scanners, digital cameras and some desktop printers.
CMYK stands for Cyan, Magenta, Yellow and Black. CMYK is also known as 4-Color Process. Cyan, magenta and yellow inks can be combined to create thousands of colors. Black ink is added into the process because even though cyan, magenta and yellow can be combined to create something close to black, it doesn’t give the desirable effect of being pure black.
Commercial printing companies produce printed pieces using the CMYK 4-Color Process method. However, many people submit RGB artwork files. These RGB files will need to be converted to CMYK prior to printing, which can be an issue because many RGB colors cannot be duplicated exactly using the CMYK process. So, there will be some variance between the RGB colors on your computer monitor and the CMYK colors on the finished printed pieces.
For example, a color that looked bright on your monitor may turn into a duller color when your document is printed. Additionally, the hues might be vastly different. Thus, it is important that you set up your artwork file(s) in CMYK and consult a Pantone Process book to see how the colors will appear as printed output. This will help prevent any unexpected results.