Additive & Subtractive Color

What the heck is the difference between RGB and CMYK color anyways? Well I’m glad you asked…

Let’s start with RGB color, or Additive color. The additive color system utilizes LIGHT. So, you begin with black (as in your computer screen). When colored light is added, whether it be red, green or blue colored light, the black begins to lighten. When all three are combined the result is white. You can see the effect shown in the graphic below. Percentages of red, green and blue are used to create color on your computer screen, LED TVs, movie projectors, colored flashlights, basically anything where colored light is being emitted.

Now on to CMYK. The CMYK (Cyan, Magenta, Yellow and Black) falls under the Subtractive color system. Subtractive color creates color variations by way of PIGMENTS. It’s called subtractive color because these pigments, when combined “subtract” brightness from white. When enough ink or pigment is present, no light will be reflected, and the result will be black.

Think of a painter. They use different color paints to turn a white canvas into something filled with color, the more color you add, the darker the result, eventually: black. I’ve seen this principle at work in my 2 year old’s paintings. She loves to use all of the colors, and loves to mix them all with the same brush. The amateur painter in me wants her to keep her color vibrant and learn to mix the color with purpose, but then I remember to exercise patience and save my lesson on subtractive color for another day… maybe when she turns 3.

Subtractive color is used in anything printed: magazines, photographs, your desktop ink-jet printer, and traditional offset lithography printing. You can see how subtractive color works in the graphic below.

Here’s a nice piece of trivia: The “K” in CMYK is short for “key plate.” In tradional offset (or 4-color or CMYK) printing a key plate impresses the artistic detail of an image, usually in black ink. That’s why we use a K to represent black.  Contrary to popular belief, the K does not represent the last letter in the word blacK.

While refreshing my memory on additive and subtractive color, I came across this interesting graphic. Found on the world wide web. It shows the visible light spectrum, which includes billions of colors. It’s interesting to see how limited our color reproduction methods are in comparison to the actual visible light spectrum. I guess this gives me a good excuse when my camera phone photos turn out so “blah.”

All of this talk about color has got us excited. I think we’ll have at least one more post on color this week. Stay tuned.

3 Responses to “Additive & Subtractive Color”

1. Sheri Holmes says:

   January 27, 2010 at 5:34 pm

   Color is amazing, isn’t it.
2. Lisa Gilbert says:

   January 28, 2010 at 1:30 pm

   I have worked in design for YEARS and I never knew that about the K in CMYK. I love that I learned something new today. Thanks for a great post.
3. Jeromy Shull says:

   May 7, 2010 at 9:39 am

   thanks, very well written post, found it through a random google search and i shared it on my stumble upon account