Color On The Computer

You are probably familiar with a color wheel that shows Red, Yellow and Blue as the primary colors. If you have tried mixing Red and Blue, thinking you will get Purple, you have probably been disappointed. When working on the computer with light (on the monitor) or preparing work for print, you need to substitute Magenta, Yellow and Cyan for those primary colors. Magenta is a very pure pink. Cyan is a very pure “sky” blue. Yellow is, well, yellow.

Working in RGB – Red Green Blue – you are working with colors of light as they appear on your monitor. These are called additive colors. When you add two colors, you get the color on the opposite side of the color wheel. The other colors have been cancelled out.

  • When you add Red light t0 Green light, you will get Cyan.
  • When you add Blue light to Red light,  you will get Magenta.
  • When you add Green light to Red light, you will get Yellow.
  • If you add all three together, you will get white light because they are all canceling each other out.

The color you see is the color that is common to the two mixed colors.

CMYK is more familiar to painters: think that you are creating color with four tubes of paint.

Working in CMYK – Cyan Magenta Yellow Black – you are working with four colors of ink. They are also called Process Colors as they are the most common set used in the process of printing colors. Black was added because so much type is printed in black, and you would have to use so much of the other colors together to make black that the ink would not dry quickly. In Process colors, K stands for Black because if B were used, it would confuse between Blue and Black.

These are the colors you buy for laser printers or most inkjet printers as well as on commercial presses. Here’s a diagram of these colors being mixed.

The color wheel for your computer is based on the relationship on colors of light. Here is a simple graphic of two color wheels; and here is an article and a link to a video about color on the computer and how to construct a color wheel using Photoshop.

Red is a mix of Magenta and Yellow. Blue is a mix of Magenta and Cyan. Green is a mix of Cyan and Yellow.

To adjust colors for either RGB or CMYK, you need to think in color “balancing” that works with the opposites on a different color wheel than the one you may have learned about in Painting or Color Theory. The computer works in RGB because it is sending color to a monitor, but when you work in CMYK, it is translating its RGB colors for you.

You can use either mode for mixing colors by changing it on your Color Panel. Chose the one that matches your destination (print or monitor). Fewer colors can be mixed with inks than appear in light so RGB will give you brighter (and more) colors. However, those RGB colors will not appear in print.

In Photoshop, some of the filters are only written for RGB so it is more convenient to work in them. Before you finalize your picture for print, it is a good idea to make a copy in CMYK and adjust for the “color shift.” Save both, and use the CMYK version for printing.

Illustrator works primarily in CMYK, but you can shift it to RGB if you know your work will only appear on monitors.

Here is another web page that explains additive and subtractive color. It is good to understand the theory, but it is critical to understand how to use the color mixers.