Offset printing is a common way of printing colored images. In this method, the image is commonly separated into four different channels: cyan, magenta, yellow and key (black). Hence the name CMYK offset printing. Every color channel is represented with a dot matrix slightly offset from the other three channels, therefore the channels do not print on top of each other. Offset printing eliminates the need for mixing many different dyes and printing them with the true color. In a way, CMYK offset printing is the paper version of the RGB (red, green, and blue) matrix of modern electronic displays. The most important difference between these two methods is that one has a white paper background to work with while the other method uses a dark screen. Therefore, unlike CMYK offset printing, RGB screens have to use full brightness of all colors to create the color white. The drawback of CMYK offset printing is that it needs a fourth channel to create the color black since printing nothing results in a white background.