March 12, 2015

Color a La Modes: CMYK vs. RGB



Physics class high school senior year is when I first learned about the color spectrum and how light gets absorbed, reflected and transmitted. My teacher, Mr. Eklund, was very knowledgable and had a spirit like Bill Nye the Science Guy. I mean, the guy built his own hovercraft! He made it out of his lawnmower. Moreover, he’d bring it to school each year and let his students take turns riding on it through the hallway!


He loved showing us experiments. Every week, we’d enter class and he’d have a new experiment ready to go, treating us like we were his audience enjoying a show rather than teaching us like the rote learners we American kids are typically trained to be. So when we were learning about colors, sure he told us that natural sunlight produces white light and is actually the combination of all the colors. But then, he showed us.


When the ceiling projector illuminated on the white pull-down screen, we saw three colored circles appear: red, green and blue (RGB). These are the primary colors of light. He noted that light’s primary colors are a little different than pigment’s—the traditional yellow, red and blue we learned in kindergarten. Then Mr. Eklund overlapped them slightly, like a color venn diagram, to reveal light’s secondary colors: cyan, magenta, and yellow (CMY). And finally, he converged them completely to show only white light—light’s tertiary “color”. It kind of blew my mind when he showed us this scientific truth.


Conversely, without light, color does not exist. Thus, we see black (K). So how is it that we can decipher the colors we see? When white light shines upon an object that has a pigment of, say, purple, all the light frequencies are absorbed into the object except for purple which reflects back in a particular wavelength in which sensation and perception then translates to purple.


At San Diego Sign Company, we deal with color translations everyday between light and pigment. Graphic art is created digitally which uses the RGB color mode since computer screens are illuminated by light. Printers, however, print using the CMYK color mode since they lay down ink. Why do we use CMYK for printing and not the red, blue and yellow primary colors from nature? CMYK are the best colors to emulate what you see on your computer screen. Then we add black ink because cyan, magenta and yellow mixed together do not make black, but a dirty brown. Plus black helps to make even more colors than we could using just CMY. Thus, the 4-color process is in fact a full-color process.

RGB is prettier, yes, but now you know better. The RGB color mode just won’t translate to print. So when creating graphic art intended for print, begin by switching your color mode from RGB to CMYK. This way, you’ll set up yourself up for a successful print quality. Moreover, simply converting RGB to CMYK (though sometimes not) will drastically change your colors, i.e., bright colors will become muted.