CMYK vs RGB: Setting the Foundation of Design

When it comes to designing your church website, student ministry t-shirts, and announcement slides without any graphic design experience, it can get a little overwhelming! We often gloss over the fundamentals of design so we can jump right into getting stuff done. Unfortunately, without setting the right foundation, it’s easy to make mistakes that could easily be avoided. These mistakes could cost you valuable time if the designs have to be adjusted, or worse, completely redone.

It’s one thing to download and memorize a “cheat sheet” of rules but having a thorough awareness of color modes will make their uses second nature. We’re much more likely to remember something we understand.

We’re starting a series called “Setting the Foundation of Design”. In this series, I’m going to take a straightforward approach to helping you understand the elements of design.

Clear. Uncomplicated. Manageable. 

So let’s get started!


What is CMYK?

CMYK represents the physical colors of ink used for the majority of print material, also called the subtractive color. It stands for Cyan, Magenta, Yellow, and Key (black). You may hear K simply referred to as black, because honestly that’s what color is most often being used. The reason it’s technically called “Key” is because black is used to add an outline and/or contrast in the four color printing process and the color black comes for the key plate.

What is subtractive color?

Subtractive color is the process of mixing a small range of physical colors (paint, ink, etc) to create a wider range of colors. This technique begins with a white background and colors are added accordingly, in specific combinations, to create to overall image.

Based on that information, you might assume it would be called additive, right? I know. It’s a little confusing right now but once we get through to RGB it will make sense.

It is referred to as “subtractive” because as the colors are added, it subtracts (absorbs) certain wavelengths of light and the colors you see are the colors that were not subtracted. I have a little method for remembering this and I’ll share it with you after the next section on the RGB color mode.

When do I use CMYK?

Because CMYK is the subtractive (absorbing) color mode, it’s easy to remember that you use it for things that absorb such as paper and fabric. If you are having something physically printed, like t-shirts or flyers for example, you should use CMYK.



What is RGB?

RGB stands for Red, Green, Blue and it is referred to as the additive color mode.

What is additive color?

While subtractive color is based on physical forms of color, additive color is based on light. Additive color is completely dependent on the use of light emitting devices such as computer monitors, cell phones, TV’s, LCD screens, etc. When it is turned off, the screen is black. In order to create color, light has to be added. The overlapping color of light has been used for many years in stage productions and there is so much to learn about it’s uses but we’ll stick with the graphic design purposes for the sake of this article.

When do I use RGB?

Because the RGB color mode utilizes light, you’ll want to use it for things that will be seen on some type of device that uses light. Things such as announcement slides, website images, app graphics, or social media posts.

Now, on to how I remember the difference between subtractive and additive color and which color mode they are associated with.

This is something I’ve come up with over the years and hopefully it makes sense to you, too. Let’s look at white (or sunlight) being the highest possible “number” and darkness (or earth) being the lowest. If we want to add depth or color to light, we have to lower, or subtract, the light. If we want to add light and color to darkness, we have to add light.

Because CMYK starts on a physical blank canvas (let’s assume it’s white for now) we have to use color to subtract the light in order the bring out depth. Thus making it the subtractive color mode.

Because RBG starts with an inactive screen (let’s assume it’s black like a computer screen) we have to add light to bring out brightness and color. This makes it the additive color mode.


Choosing Your Color Mode




From the New Document Window

Photoshop: In the new document window, Color Mode is directly below the Resolution option.

Illustrator: In the new document window, you have to expand the “Advanced” section to show the option to adjust the Color Mode.


From an Existing Document

Photoshop:  Image > Mode>  select your new color mode

Illustrator: File > Document Color Mode > select your new color mode

NOTE: Changing the color mode of a document (especially when going from RGB to CMYK) can drastically shift the look and colors of your document. Try to start with the right color mode when beginning a new project.


Was this article helpful? Do you have any questions about color modes? Let us know! We;d love to hear from you.


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