Color Blending Color Theory

I am very excited to share this color blending color theory post with you today! It’s pretty technical at the beginning, but trust me, I wrap back around to discussing how this applies to fabric selection for quilting projects.

During a recent Wayward Transparency workshop that I was teaching, where quilters apply fabric selection techniques to create a transparency design, one quilter had a great question for me: if you know the CMYK values of two of your fabrics, can that help you determine what the CMYK value of a third fabric should be? On top of that, she told me about a free app she had downloaded called What a Color? The app samples the color content of an image and can give you the RGB, CMYK, HSB, HEX, and LAB values for any selected color within the image.

During our lunch break during the workshop, I dove into being able to answer the first question by opening Adobe Illustrator. By using the color blending capability within Illustrator, I was able to answer the CMYK question.

The video above is the process of how to create a color blend within Adobe Illustrator. The color theory behind the average color blending (in the example above shown as blending between red and yellow to make orange) is really simple: to get the perfect blend between two colors, find the average of each of the CMYK colors. So, if your Red has a CMYK of (15, 100, 90, 10) and your Yellow has a CMYK of (5, 0, 90, 0), the perfect blend Orange would have a CMYK of (10, 50, 90, 5), as detailed below:

• C = Average of Red C and Yellow C = (15+5)/2 = 10
• M = Average of Red M and Yellow M = (100+0)/2 = 50
• Y = Average of Red Y and Yellow Y = (90+90)/2 = 90
• K = Average of Red K and Yellow K = (10+0)/2 = 5

I repeated this process over and over and the result of a color blend was always the average. As CMYK was created as the basis for printing color, having a clear mathematical method for combining and creating colors makes sense to me. I continued to deep dive a little bit more and learned that RGB is known as additive and CMYK is known as subtractive. Your computer screen displays in RGB and printing uses CMYK. If you want to join me in the deep dive, I recommend this What is CMYK? article.

The next thing I wanted to evaluate and understand was the What a Color? app, which had to wait until the workshop was over.

Sunburst in What a Color? App

I imported an image of my Sunburst quilt into the What a Color? app. As you can see in the screenshot above, as you highlight different areas of the photograph, the app identifies the color to the closest color in its database and reports its RGB value. If you tap on the name of the color (in this case, Rich Electric Blue), you get more information about the color.

Rich Electric Blue

The What a Color? app identifies the CMYK value of Rich Electric Blue to be (99, 34, 0, 17). It also shows similar Pantone colors, which indicates to me that its database is comprised of Pantone colors. Since Pantone publishes this information about their colors, I did a quick search. I did not find a Rich Electric Blue, Medium Blue C, or Process Blue C in the Pantone data base, but I did find 639 C. So then I searched by the listed CMYK values and there was no closely representative Pantone color. Scratching my head a little bit, I decided to cross compare the values given for the color in Adobe Illustrator.

When I imported this screenshot into Adobe Illustrator and use the eyedropper tool to evaluate the shown Rich Electric Blue color, it gives the CMYK as (80, 36, 0, 0).

Sunburst Evaluated in What a Color? App

Continuing the evaluation, here are 3 of the colors in Sunburst as identified and labeled by the What a Color? app and how the CMYK values compared to when I evaluated the screenshots in Adobe Illustrator.

• Rich Electric Blue
  • What a Color? app CMYK (99, 34, 0, 17)
  • Adobe Illustrator CMYK (80, 36, 0, 0)
• Robin Egg Blue
  • What a Color? app CMYK (91, 13, 0, 10)
  • Adobe Illustrator CMYK (66, 0, 11, 0)
• Maya Blue
  • What a Color? app CMYK (60, 7, 0, 9)
  • Adobe Illustrator CMYK (53, 0, 12, 0)

Assuming that the CMYK of the outer two colors (Rich Electric Blue and Maya Blue) are correct, these are the theoretical perfect blend CMYK values:

• What a Color? app CMYK (80, 21, 0, 13)
• Adobe Illustrator CMYK (67, 18, 6, 0)

According to the What a Color? app, the middle color is closer to Rich Electric Blue than it is to Maya Blue. According to Adobe Illustrator, the middle color is a reasonable blend of the two outer colors.

You might be thinking, well, that’s great Yvonne, but what does all that mean for fabric selection? The bottom line is that theory is all well and good, but we as quilters are going to be limited by the fabric options that we have available to us. I’m not convinced that the What a Color? app does a great job of listing the correct CMYK values, but it is a free resource that can be downloaded an used, as opposed to Adobe Illustrator, which is not a cheap software to license.

When using any tools to evaluate fabrics under consideration for a quilting project, these are my top recommendations:

1. Photograph the fabrics you are considering together in the same photo.
2. Take the photograph, if possible, in diffuse natural light.
3. Adjust the photograph to look as much like what you see with your eyes as possible.
4. Then use software of your choice to further manipulate and understand the relative nature of the fabrics to one another by learning about their CMYK values, converting the image to grayscale, etc.

And if you are looking for more great resources, I recommend:

1. Color Wheel: Harmony by Steph Skardal
2. Palette Builder by Anne Sullivan
3. Take Great Photos Now! by Kitty Wilkin
4. Converting Images to Grayscale
5. Playing with Color – Transparency Tutorial
6. Evaluating Fabric Contrast 
7. Evaluating Fabric Color & Value Tips
8. And of course, my Transparency Fabric Selection Tips and Tricks Virtual Lecture and/or Transparency Workshop!