RGB vs. CMYK: What’s the Difference?

“Why did my colors change from what I see on screen to the finished product?”

That is a valid and common question for people new to digital process printing.

Since screens are backlit and operate with the RGB (red-green-blue) color space, RGB cannot be replicated exactly with CMYK (cyan-yellow-magenta-key [black]) because it isn’t backlit and is a more limited color space. The colors tend to skew darker and less vibrant than what you see on screen.

So, what’s the difference between RGB and CMYK? Let’s dive in!

RGB (Red-Green-Blue)

Additive colors are developed by adding a certain amount of red, green, and blue light onto a black background. It’s called additive because it takes the screen from the absence of light (black) and displays a specific color by adding light. When red, green, and blue are combined equally, the light is white.

CMYK (Cyan-Yellow-Magenta-Key [Black])

Subtractive color is a little tougher to grasp as a concept. The eye sees color because specific wavelengths of light are either reflected or absorbed by a surface. All of the wavelengths being reflected show as white. The more light is absorbed (read: subtracted) by a substrate, the darker it appears. Therefore, using equal applications of cyan, magenta, and yellow inks should yield black. That isn’t the case. The result is a muddy brown, which is why using black is necessary for the CMYK printing process.

Since your device screen emits light, instead of reflecting from another source, it creates the illusion of specific colors well enough to trick the human eye. However, CMYK digital process printing uses a combination of those four colored toners on paper to reflect light because it doesn’t have a light source like a device screen.

Ultimately, process printing has its limitations. The colors it can create are fewer than what the human eye can see, which is less than what device screens can simulate. Therefore, designing on a backlit device screen, even using the CMYK color space simulation, gives a brighter, more vibrant example than can be replicated.

How can I get an accurate idea of how colors will print?

48 Hour Books recommends using CMYK color space and turning your brightness of your screen down to about 30%. This will give you the most accurate representation of how your color will look printed when viewing it on your screen.

If you want to be 100% certain of how your color files will print, we strongly recommend ordering a printed proof before you sign off on your order. This is the best way to know for sure you will be completely satisfied with the color and will allow adjustments to be made before your full order goes to print.

As always, we’re here to help! Our expert pre-press technicians are here to answer all of your file questions. Contact us today before you get started!