RGB color profiles
Red, Green, and Blue (RGB) are the three primary colors of light. In any light generating device (like computer screens), RGB blends these three colors to produce all other colors.
There are two types of color profiles: additive and subtractive. RGB is an additive profile because you create new colors by adding primary colors of light together.
Green light + blue light = cyan Blue light + red light = magenta Red light + green light = yellow Red light + green light + blue light = white
With RGB, the color gamut is very wide, so it can produce a broad range of colors. This is because it essentially mirrors how our eyes see color. In our retinas, we have three different kinds of cone cells that pick up on red, green and blue light. Our brain then blends together the different signals that the cells receive, producing an astonishing array of color.
Of course, this all depends on one key factor: light. Anything that’s printed doesn’t generate light, it reflects it. So, how do you reproduce color in print, if there’s no light source?
The answer is that you don’t add, you subtract, which is where CMYK comes into play.
The RGB color model
CMYK color profiles
CMYK stands for Cyan, Magenta, Yellow and blacK (also known as K for Key). These four colors of ink are blended to create colors on items that reflect light, like paper or fabric.
Unlike the RGB, where you create colors by adding two or more together, CMYK is a subtractive color profile, so you you remove a primary color of light from any white light that hits it.
White light (such as daylight) appears visible to the naked eye, but that doesn’t mean it’s void of color. In fact, white light occurs when all colors of the visible spectrum appear in roughly equal amounts. By playing with these amounts, we can subtract wavelengths and produce different colors.
- Cyan ink reflects green and blue light, but not red
- Magenta ink reflects blue and red light, but not green
- Yellow ink reflects red and green light, but not blue
To produce the three primary colors, you have to think in reverse.
- By combining cyan and magenta, you only reflect blue light
- By combining magenta and yellow, you only reflect red light
- By combining yellow and cyan, you only reflect green light
Imagine you have a piece of white paper. It’s white because it reflects every wavelength of light. By using cyan, magenta and yellow in different proportions, you subtract specific colors of light to produce a wide gamut of colors.
Now, in theory, by combining cyan, magenta and yellow you should get black. But our eyes perceive color the RGB way, meaning the CMY doesn’t produce a perfect result. To combat this, we add in black ink (key). The black ink will absorb all light and provide darker tones and richer blacks.
The CMYK color model
Converting RGB to CMYK
Since the CMYK profile works on a subtraction theory, its color spectrum is limited when compared to RGB. Vivid primary light colors (pure red, green and blue) will often appear less vibrant when converted to CMYK.
In the image, you can see the gamut of available colors with several RGB profiles, and those available with CMYK. The range of what you can achieve with RGB is much greater than CMYK.
Please note that if you upload RGB files to our print ordering system, they will be automatically changed to CMYK values. While we believe that our conversion system is very good, we recommend creating your own specific CMYK color for printing to help avoid disappointment.
How to stay in the CMYK gamut
In Photoshop, InDesign or Illustrator, an ‘out-of-gamut’ warning may pop up in your color picker tool. If you see this triangle with an exclamation mark, you’re being informed that your chosen color may not print accurately with CMYK.
While the program may suggest a similar color that does appear within the gamut, we have also compiled a list of suggested CMYK color values which should print consistently.
Working with RGB and CMYK profiles
Everything printed on paper will have a CMYK ink color profile. Similarly, anything created to be viewed on a computer screen will have an RGB color profile. So if you’re creating a booklet for example, you will want to start your designs in CMYK and print in CMYK.
However, if you were to create a webcomic, you would begin by designing in RGB so it can be better viewed on the web. Then you would convert your files to CMYK and manually adjust any colors that may not look quite right before printing them. This is because starting in CMYK for online projects can restrict the creative process due to the more limited choice of colors.
To get a quick impression of what your RGB project will look like in CMYK, simply switch to CMYK Mode in Photoshop or InDesign. Then you can easily see which colors may need adjusting.
If you are using a color profile we recommend GraCOL2006.
If getting the perfect color is crucial to your project, we recommend ordering a proof of your project to see how it turns out. If you have any questions, please contact our team of print experts. We’re always happy to help.