RGB vs CMYK
I have long known as a fact that RGB is the color space used to code for digital images and CMYK is the color space used to code for printed materials, but I had never considered why. Then last week, I was leading a meditation, and one of the comments from a participant at the end made me realize the difference between RGB and CMYK.
In that meditation, I led the group through a practice that involves breathing in light and breathing that light out as a color. It was okay for it to be any color. I asked the group the notice that color and created a space at the end for people to share their experience. One person, my friend’s mom, who happens to be a painter, shared that her light was a bright white. In response, I commented that it was lovely that white light is the combination of all colors of light, so it was almost as if she was seeing all the colors in seeing bright white. As a painter, she paused at my comment. It took me a moment, but I quickly figured out why she was confused.
I made my comment because I am more familiar with color in the context of light in physics. Different wavelengths create different colors of light. Our eyes are sensors that detect certain wavelengths of light. We call that range of light the visible light spectrum, defining it by our own abilities to perceive. The light that’s not visible, including infrared, literally meaning below red’s wavelength, and ultraviolet, literally meaning above violent’s wavelength, is just as real, but naturally less important to us. When we combine the colors of light, they make other colors. And if we combine red, green, and blue, they make what we perceive as the color white, which is actually a mix of multiple wavelengths of light.
If you are reading this post on Medium with a white background, you may be able to see hints of rainbowy color in the white background. Every pixel display true white is rapidly cycling between red, green, and blue, so your eyes may be able to detect a subtle trace of that. It was this understanding of the color white, this combination of different wavelengths of light that doesn’t exist on its own as a single wavelength, that informed my comment on the color white. But if I had remembered the lessons of my elementary school days, splashing paint onto paper with my bare hands to experiment with and learn about colors, I could have anticipated how my comment might run amiss. In the physical world of paint and pigments, white is the exact opposite of what it is in the world of light.
In painting, white is the absence of color. Pigments are color. The lesson long buried in the depths of mind and brought back my friend’s mom’s comment is that when you mix all the pigments together, it makes black. In the world of light, black is the absence of color. In the world of pigments, black is all of the colors. It seems as if these world of light and matter are completely divergent, yet every color that can exist in light can be replicated in pigment. We can reconcile these two.
The lighting environment we’re in skews our perception of color, which is a small hint as to the nature of color in our physical world. What we’re seeing when we perceive color is light that is reflecting off of objects in the physical world. That’s why when there’s no light, we see no color — the world goes dark, which is what we understand to be the default state. The sun brings us the most literally brilliant array of all the wavelengths of light, and when we perceive color, what is actually happening is that some of the white light is being removed.
Creating light on a computer screen is an additive process. The default screen is black, and by combining red, green, and blue we can create any color of light including white light when we combine them all. In the physical world, the sun fills our space with white light, and pigments are materials that absorb some of those wavelengths of light but not all. When we see a material that is blue, it is absorbing the red and green wavelengths, so all that is reflected back to our eye is the blue. Adding more of a pigment absorbs more light.
In the CMYK of print, the first three letters represent the colors cyan, magenta, and yellow. The K stands for key, or the key color, which is the black that one gets when combining all three. The CMY also maps neatly to RBG in that yellow and magenta make red, yellow and cyan make green, and cyan and magenta makes blue. The major difference between RGB and CMY, and the reason code colors different for digital and print, is that RGB is an additive process that creates colors from black by putting them together. CMY is a subtractive process that creates colors by absorbing and thereby removing wavelengths from white light. When we see black in our physical world, that material or space that we see as black is absorbing all light so none can be reflected back to us. These different systems are really two sides of the same one, revealing that my earlier conundrum was really a lesson for me in perspective.
Whether white is all of the colors or none of the colors is just a matter of whether we are talking about light, like in a computer screen, or pigments, like in paint. My comment, that white light was all of the colors, was literally the opposite of my friend’s mom’s understanding of the world. Yet her understanding and my understand were both correct. This little revelation reminded my that so often our differences, even when we are in total opposition, simply boil down to a difference in perspective. Depending on the frame, we may all be correct.