When creating pieces for print while looking at a computer monitor all day long, it’s easy to forget the colors you’re viewing on screen do not reflect how those colors will appear once they’ve been printed. Computer monitors, smartphones, tablets, and televisions create color by combining red, green, and blue light (RGB). Many of today’s screens are capable of displaying millions of color with great clarity, vibrancy, and contrast creating lifelike, vivid images. However, while offset printing is capable of reproducing images with great clarity, it’s not capable of reproducing all of the colors an RGB screen can display.
Additive (RGB) vs. Subtractive Color (CMYK)
Additive colors are colors created when wavelengths of light combine and are perceived by our human vision system (eyes, retina, optic nerve, and brain). The intensity of the light wave perceived determines its value (how light or dark) and the size of the wavelength of light (or its vibration) determines its perceived color or hue (i.e., red, blue, yellow, green, etc.).
Subtractive color is when lightwaves are absorbed by a material or substance such that the perceived color consists of lightwaves not absorbed by the material or substance but are reflected to the eye. In a certain sense, additive colors can be thought of as being colors perceived directly via a light source and subtractive colors are colors perceived via reflection from a light source. From this perspective, additive colors have the upper hand in terms of how many colors humans can perceive.
The Limitations of CMYK
Full-color offset printing, also known as 4-color or 4-color process printing, uses four standard, semi-transparent ink colors: cyan, magenta, yellow, and black (CMYK) overlaid in a circular dot pattern (known as rosettes) to create a broad spectrum of colors. Because CMYK inks contain impurities, they cannot recreate the purity of additive colors perceived directly. Also, unlike additive colors where light and dark are determined by the intensity of the lightwave (white = all lightwaves combined; black = complete absence of light), CMYK must use black ink in combination with the whiteness of the paper substrate and transparency of the inks to approximate the range of values human eyesight can perceive.
Graphics Software Simulation
Professional graphic software programs (like those offered by Adobe) include settings that emulate what colors will look like when printed via CMYK processes. It’s important to keep in mind these simulated CMYK colors are only approximations at best. However, they can serve as a reminder to make sure all parties involved in a print project are aware that at least in terms of color when looking at a screen, what you see is NOT what you get.
If you have any questions about RGB and CMYK, give us a call at 330-597-8560. We’re happy to help you get the most out of your printing project.
Photo by Jeremy Thomas
