RGB versus CMYK – Signage 101

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Arguably one of the most important aspects of printing is, well, color. Without it, signs can be boring and one dimensional. Color is all around us, but you may have noticed that sometimes a color looks different on the screen than it does when it gets printed. It’s important to understand how color works. For this Signage 101 Blog Post, we’ll explore how different color modes can affect printing.


When Newton was studying light, he observed that objects don’t inherently have “color” as a property. Red is not “in” an apple. The surface of an apple is reflecting the light wavelengths we see as red and absorbing the rest. We perceive only reflected colors.

How eye sees color

The light of the color “red” travels through our eye through the iris. The light is collected by the rods and cones in the back of the eye. Cones allow us to see color, while rods establish things as black or white. These cones and rods process the light we see into nerve impulses and transmit signals to the brain via the optical nerve.

Inner Eye Workings

The human eye is only made up of red, green, and blue cones. About 64% of the cones in the normal human eye see red, 32% see green, and only roughly 2% see blue. Because of this breakdown, humans can see more variations in warmer colors (reds, oranges, and yellows) than cooler ones (blues, greens, purples).

Color blindness occurs when there is a defect in one color of cones. The most common impairment is trouble seeing red and green (called dichromatism). Only about 8% of men and 1% of women experience some sort of color blindness. Total color blindness is extremely rare.

Our brains have a very acute sense of color. With these three types of cones, the human eye is able to see over 7 million color variations.


When designing graphics,  it’s important to understand the difference between RGB, CMYK, Hex Colors, and PMS Colors. These are called “Color Modes”. For lack of a better explanation, they are basically different ways in which you tell the computer, monitor, or printer which colors to print. Think of them as each a different language built for different situations, all trying to explain the same thing. On a day-to-day basis, we interact with each of the different color modes. We’ll break them down here.


RGB stands for Red, Green, and Blue. All of the colors are created use a combination of red, green, and blue light.  

RGB Color Wheel

RBG is what’s known as additive color. Each color adds to the brightness from dark; all colors begin with black to which different color of “lights” are added to produce colors. Additive color uses light reflection. The more of each color you add, the closer you get to “pure” white. The less amount of color you add, the closer you get to black.

Think of it in terms of the way your eyes work, as discussed earlier. If you’re standing in a pitch black room, and you begin to add light, you are able to begin to see colors and decipher objects. The light is able to bounce off each object. Add too much light, and you get a “blinding white light”, or having all the lights on at full brightness.

RGB Color Mode is used for anything that is light-based. Televisions, computer monitors, cameras, and even iPhones use RGB. RGB codes are represented with a number between 0 – 255 for each red, green, and blue.

RGB Color Slider

These numbers tell a device how much of each colored light to put out. 0-0-0 gives you true black, while 255-255-255 gives you white. The larger the number, the less of the color is present.


Hex Colors, normally called HEX Codes, is an alphanumeric reference to a RGB number. Typically HEX codes are used for websites and coding because they are shorter and easier to work with in website development than a set of three numbers.

HEX is short for hexadecimal. Each of the three RGB colors is assigned a two-digit code (0-9,  A-F) based on percentage of each of the RGB colors. For example, an RGB color that is 17-210-45  has a HEX code of 11D22D.

Hex Colors Breakdown

The easiest way to establish a HEX code from a RGB color (or vice versa) is to use a color conversion site like RGBto. Simply type out whichever value you have, and the website will list its corresponding values in HEX code and CMYK. Handy!

Color Code Converter Image


CMYK stands for Cyan, Magenta, Yellow and a “Key” color (black). All colors are created using a combination of those colors. The colors are similar to what you remember from elementary school. 100% Yellow and 100% cyan make green. Magenta and yellow create red.

CMYK Color Wheel

However, unlike RGB, CMYK colors are subtractive colors. Each color subtracts brightness from white. Subtractive colors use light absorption rather than reflection. All colors begin with white, to which different colors are added to absorb (subtract) the amount of light that is reflect.The more of a color you add, the closer the color will be to black — exactly the opposite of the properties of additive RGB color.

Think of it, again, in the way light works with our eyes. When looking at an object, if the object is seen as being black, it is because it’s absorbing all of the different wavelengths of light.

CMYK is used for anything that’s printed. Business cards, posters, signs, newspapers, books, etc. all use CMYK. CMYK colors are represented in percentages from 0-100%.

CMYK Color Slider

These numbers tell the printer how much percent of a color to mix in to create the desired color. 100-100-100-100 gives you true black, while 0-0-0-0 gives you white. The larger the percentage, the more of the color is present.


PMS stands for “Pantone Matching System”, a universal color matching system used to create color consistency across a wide variety of platforms, materials, and uses. Pantone colors were created by the Pantone corporation and offer over 1100 unique, numbered colors. PMS systems are used widely in graphic, fashion, and home design.

Pantone Colors Green

Color, as we’ve seen, can be very subjective. PMS colors standardize color, which means manufacturers and customers can all refer to the Pantone system to make sure colors match.

Pantone colors, unlike RGB or CMYK, are based upon standardized ink colors rather than ratios of color. They are much like a paint swatch you’d find at a home improvement store. Rather than mixing different layers of ink during the printing process (like in CMYK), Pantone colors are mixed before they even get put into the printer. The familiar yellow of the McDonald’s arch or the green of the Starbucks logo remains consistent whether you’re viewing it on a TV or in a print ad because of the use of Pantone colors.

Walmart Logo Colors

Colors are assigned a number by Pantone, who then uses the number across a variety of palettes. Textiles, coated printing material, uncoating printing material, paint, and even plastics have their own Pantone color book, like the one pictured below.

Pantone Book of Colors


Most of the printers used at Signs.com use CMYK color processes. Signs.com does not print any Pantone inks directly. However, we want to make sure you get exactly the product you need for your home or business.

Color Matching Pantone Services

Signs.com can provide a color matching service, which takes the Pantone color you’d like to use and converts it into a printable CMYK color. Pantone does provide formula guides that illustrate PMS colors and how they will look once printed. Since this process is hand-done by a professional staff, it is an additional charge of $100 per color and may take additional time to finish your order. If the Signs.com Color Matching service is something you’re interested in, please let our Customer Service team know.


You bet! Sometimes drastic changes can be seen. Take a look at these two lines of dots:

Color Dots-01

Color Dots-rgb-01

You may see the RGB colors on screen, but what will print will be the first line of CMYK dots.

It’s easy to see that with the different color modes, colors can come out looking completely different. Colors never look the same from screen to print. If you’re printing something, be sure to always use CMYK color modes.


Our eyes have a visible spectrum of billions of colors. High quality monitors and screens can produce millions, and really high quality printers can produce thousands of colors. When designs are created for printing in the RGB color space, Signs.com will automatically convert the design to a CMYK color space in order to print.

Beginning your design in RGB is the best option. Our team has a lot of experience changing from RGB values (that our website displays) into CMYK files for printing. Uploading your file in RGB mode gives you the best idea of how the file will look when printed.

Please note that unless you pay for our color matching service, we can’t guarantee that the color will be exactly as you see it on screen.


Checking which Color Mode you’re using is different in each program. Files created in Microsoft programs like Word, Paint, or Publisher will naturally be set up for use in CMYK. RGB color modes are not possible in basic Microsoft programs.

Checking the Color Mode is easy in Adobe Programs.

Checking Color Modes In Adobe Illustrator or InDesign

1. Open the file. On the top menu bar, select “File”.

Checking Color Mode 12. Click on “Document Color Mode”, near the bottom of the menu options.

Checking Color Mode 2

 3. When “Document Color Mode” is highlighted, a new menu will open to the left of the window. RGB Mode and CMYK Mode will be displayed. The mode that the document is set up in will be        indicated with a checkmark. You can easily change the Color Mode of the document by clicking either RGB or CMYK.

Checking Color Mode 3

Checking Color Modes in Adobe Photoshop

1. Open the file. On the top menu bar, select “Image”.

Checking Color Mode Photoshop 1

2. Click on “Mode” at the top of the menu bar.

Checking Color Mode Photoshop 2

3. When “Mode” is highlighted, a new menu will open to the left of the window. RGB Mode and CMYK Mode will be displayed. The mode that the document is set up in will be indicated with a       checkmark. Easily change the Color Mode of the document by clicking a new option.

Checking Color Mode Photoshop 3

Establishing Color Mode in a New Document

When creating a new document in Adobe InDesign or Illustrator, the “New Document” menu will open. Under the “Advanced” section, you are able to select whether you’d like the file to be CMYK or RGB.

Changing Color Mode New Document Image

Similarly, in Photoshop, changing the Color Mode is an option before creating a new document. Simply choose the drop-down menu option next to “Color Mode” to change from RGB to CMYK.

Checking Color Mode Photoshop

Quick Check

To quickly check if a document you have open is in CMYK or RGB mode, take a look at the file name tab in the top left.

Quick Check

The bar will give you the name of the file and whether the document is set up in RGB or CMYK. This works for any Adobe Illustrator, Photoshop, or InDesign file.

If you need help setting up documents or help with your design, drop our design team a line! If you have any other questions about your order, let our Customer Service team know. We are always ready to assist you!

Color Mode Glossary

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