January 2, 2014

FAQ: What is RGB color versus CMYK color?

I'm going to start a series of articles on various subjects that are common knowledge to graphic designers but not to businesses that hire them.

Let's start with colors.

Most people think of light being composed of red, green, and blue. And that is a useful model for colors of light. Cameras and computer screens use this model, and call it RGB. It's an "additive" model - colors of light are added, and enough of them add to make white light. Here's a picture of how RGB colors combine.

But printers don't print with light; they print with ink. Usually you start with white paper, and add ink, which effectively subtracts (reflective) light. So it's called a subtractive process.

The most common model for representing printed colors is called CMYK, for the four colors used: cyan, magenta, yellow, and black (the "K"). This is call "process" or "four color process" printing. Black is used because without it, you get to a muddy, dark gray, not a crisp black color. CMYK colors look like this:

So who cares, right? Well, if you take an RGB photo and print it on a CMYK printer, you will, if the colors change in the conversion process. And they often do. And some RGB colors cannot be exactly converted to CMYK (and vice versa). And finally, when you review a design sent from your graphic designer, looking at it on your computer monitor, remember that you are looking at RGB colors, no matter how the design was made. Getting a test ("proof") print is essential if you want to make sure you are satisfied with the colors it will print in.

Professional graphic design software can work in either RGB or CMYK color mode. Which one is chosen depends on the application the designs are intended for (web use or print).

Your graphic designer can help ensure that your images look as good as they can, given these color complexities.

>Please suggest other topics for explanation by using the on my main website.