Manipulate Color to Create Optical Illusions

Manipulate Color to Create Optical Illusions is the last in a five (5) article series by MJ Kinman, maker of her signature gemstone quilts. MJ is taking us on an adventure in color unlike any you may have experienced. She has taken the words and wisdom of influential artists and theorists such as Josef Albers and M.E. Chevreul and interpreted them in ways that we as quiltmakers can use in our own work.

MJ will explore this topic in more depth during her lecture at QuiltCon 2025 (February 20-23) in Phoenix, AZ. To register for MJ’s “Color Play” lecture, visit https://quiltcon.com/faculty/.

This week, MJ shows us how to manipulate color to create fascinating optical illusions. Be sure to check out the four previous articles, too! The ideas MJ are sharing with us are applicable to all quiltmakers, regardless of their inspiration, and are intended to help makers approach color with confidence and joy.

Learn more about manipulating color in the other articles in this series:
Article 1: Unlock the Secret of Color Interactions
Article 2: Make Your Quilts Glow with Saturation Contrast
Article 3: Add Sparkle to Your Quilts with Value Contrast
Article 4: Add Depth to Your Quilt Designs with Effective Transparencies

Overview

“Color deceives continuously.” When I read that statement in Josef Albers’ landmark book Interaction of Color, I was intrigued. So many of the students in my classes feel less than confident when working with color and, quite frankly, so do I.

However, once I understood some of the ways color tricks us, my confidence level increased. The following article summarizes these ideas so that you can better understand how colors “behave” around one another. I also hope to show you ways you can manipulate color in your own quilts and even create some fascinating optical illusions. Grab your color wheel and let’s get started!

Revisiting the Law of Simultaneous Contrast

A French chemist named Michel Eugene Chevreul was drawn into the study of color in the early 1800s. As a consultant for Gobelin, the famous maker of royal tapestries, Chevreul helped artisans create sparkling, glowing effects in their work. He also helped them understand why their color combinations didn’t always hit the mark. Chevreul is credited with heavily influencing the Impressionists of the late 19^th century and abstract artists of the early 20^th century like Robert and Sonia Delauney.

His study led him to a groundbreaking observation: When the eye views two colors in close proximity, it adjusts to make them as dissimilar as possible. Chevreul called this “the law of simultaneous contrast”. In other words, the juxtaposed colors are simultaneously exerting influence on each other in terms of value contrast and color contrast.

Can we predict how these colors will change or — as Chevreul termed it — are made “dissimilar”? Yes!  Let me simplify his idea by listing three simple rules that underlie his findings:

Rule #1 — When two juxtaposed colors are not of the same value (i.e., different lightness or darkness), the darker one appears even darker, and the lighter one appears even lighter. Chevreul described this by saying that the two colors “exalt” one another.

Rule #2 — When two juxtaposed colors are not of the same hue, each color seeks to add its complementary to the other. For example, reds will cause other colors next to it to take on a greenish cast (red’s complement), blues will cause other colors next to it to take on an orange cast (blue’s complement).

Rule #3 — When two complementary colors are placed next to one another, they enhance one another. For example, if red and green are placed next to one another, both the red and green will look more vibrant. As I mentioned in Rule #1, Chevreul describes these colors as “exalting” one another.

Examples of Chevreul’s Rule #1 in Design

Let’s explore Chevreul’s Rule #1 and how you can use it in your quilt designs.

Create Fluted Effects Using Value Progression

The next image is of five bars arranged in a progression from light to dark. Look at the very center of the image and relax your eyes. Do you see the optical illusion start to emerge?

As I gaze at the image, the lower portion of each bar appears darker than the upper portion. It begins to take on a gradated or fluted effect. However, each bar is an even, solid color. To prove this, I’ve cropped the image above so that only the middle bar is visible below. There is no appearance of fluting when it stands by itself.

Why does this happen? Remember Chevreul’s first rule: when two juxtaposed colors are not of the same value, the darker one appears even darker, and the lighter one appears even lighter. They “exalt” one another.

You now have the language to explain what’s happening in the image above. The light bar is “exalting” the edge of the dark bar above it by making it appear even darker. Conversely, the dark bar is “exalting” the edge of the light bar below it by making it appear even lighter.

Take away: You can create interesting depth and texture to your quilts by creating these types of value progressions in your design.

Make One Color Look Like Two

Here are several more examples of Chevreul’s first rule in action, specifically how we can use it to make one color look like two.

The image above depicts a quilt block I designed for my 2021 Tiny Treasures online club. One day I noticed that the facet labeled “A” appeared to be lighter than the facet labeled “B”. Having designed the block, I knew they were the same color. Why then did A look lighter?

We know the answer! Look at the pieces surrounding “A”. Now look at the pieces surrounding “B”. The pieces surrounding “A” are much darker than those surrounding “B”. We know from Chevreul’s Rule #1 that the dark pieces enhance the lightness of “A” making it appear lighter. The light pieces surrounding “B” don’t have the same impact.

The image below brings this point home in a different way. Compare the small brownish squares set in the navy blue and yellow squares. To my eye, the small square on top looks lighter than the one on the bottom.

By now you’ve probably guessed that they are the same color. You’re right! When I remove the overlapping horizontal bars, you can see that the vertical brownish bar is one consistent color.

Why is this happening? The combined impact of the dark navy background square and the black horizontal bar makes the small brownish square appear lighter than it really is. Conversely, the combination of the yellow square (the lightest color on the color wheel) and the light blue horizontal bar make the bottom brownish square appear darker than it really is.

The take-aways:

• When you want a piece of fabric to look lighter, surround it with much darker fabric.
• When you want a piece of fabric to look darker, surround it with much lighter fabric. 

Examples of Chevreul’s Rule #2 in Design: Pushing Colors Toward the Complement

Chevreul’s Rule #2 states that when two colors are not of the same hue, each color seeks to add its complement to the other. For example, reds will cause adjacent colors to take on a greenish cast (red’s complement).

Why does this happen? Scientists suggest it has something to do with our brain’s need to seek harmony and balance. Others have gone further to explain that our eyes contain mechanisms called “cones” that perceive color. We each have three types of cones that perceive different wavelengths of color. When one set of cones becomes fatigued by seeing only one range of color, the other cones try to take up the slack by searching for the other wavelengths.

In other words, if I’m staring at an image that’s primarily blue, the “blue” cones become fatigued. At that point, the other sets of cones become active and search for orange, the complement of blue. Orange contains wavelengths of the two other primaries, red and yellow. I like to think of this process as our eyes attempting to “load balance” color across all sets of cones.

We can use this concept to create interesting optical illusions, like the one Picasso achieved in his painting “Old Guitar Player”. Picasso’s painting is primarily blue with a splash of brown in the guitar.

Brown? Are you sure?

I used the Color Picker tool in a photo-editing app to sample the color of the guitar. To my surprise, the guitar turned out not to be brown at all; it’s a grayish green!

Why then do we perceive a “brown” guitar? Chevreul’s second rule gives us the clue. Our brain is pushing the actual green of the guitar towards the complement of blue, which is orange (the underlying hue of brown). Picasso painted the guitar a grayish green, but our brain is tricking our eyes into seeing brown because of the impact of all the blue in the image.

Here’s another example of how our brains push colors toward the complement. I’ve dropped a pale beige square onto a larger blue square and a larger yellow square.

Gaze at the boundary line between the blue and yellow squares. Relax your eyes and take note of the two beige squares in your peripheral vision.

My eyes detect a difference between them. A subtle orange cast seems to overlay the small square on the left, and a purple cast appears to overlay the square on the right.

Why? Our brains are “adding” the larger square’s complement to the smaller square, as Chevreul predicted. Orange is the complement of blue, so the beige square in its center takes on an orange cast. Purple is the complement of yellow, so the beige square in its center takes on a purplish cast.

The take-away:

•  If you are using large and small squares in your design, the smaller squares are likely to appear as if the complement of the larger square has added to it. This will result in the same squares of color appearing slightly altered when surrounded by different color fabric.

Combining Chevreul’s Rule #1 and Rule #2: Make Two Colors Look Like One

This brings us to my final – and favorite – optical illusion that can be explained by Chevreul’s first and second rules: make two colors look like one. Based on what we’ve just learned, we now know how to make this happen. Here are our clues:

• To lighten a color, surround it with a darker color and vice versa. (Rule #1)
• To push a color to look like another color, surround it with the complement of the color you’re seeking. (Rule #2)

You’ll want to be sure your color wheel is close by for these examples.

Let’s say we want to change the appearance of a taupe square and a grayish green square so that they look more similar than different.

Let’s work on the taupe square first. We want it to look darker and a bit greener. Based on what we’ve learned, here are steps we can take:

• We know that the background color should be lighter than the taupe square in order to make the taupe square appear darker.
• We also know that the background should be a version of red (the complement of green) to make the taupe square look greener.
• Conclusion: Select a fabric that is both light and a version of red. In other words, you want to select a pink fabric.

Now let’s work on the green square. We want it to look lighter and more yellow, taupe’s underlying color.

• We know that the background color should be darker than the green square in order to make the green square appear lighter.
• We also know that the background should be a version of purple, (the complement of yellow) to make the green square appear more yellow.
• Conclusion: Select a fabric that is both dark and a version of purple. In other words you want to select a dark purple fabric, such as eggplant or indigo.

Below are the combinations I selected. Gaze at the vertical boundary line between the two squares and let your eyes relax. Take note of the two small squares in your peripheral vision.

My brain sees two small squares that are similar in value and color. What do you see?

When I swap out the taupe and greenish, you’ll see exactly how different they really are. In fact, now that they are on backgrounds that “exalt” them, they appear to have enhanced characteristics. In other words, the light pink background on the left makes the dark green square even darker and greener. Similarly, the dark purple background on the right makes the light taupe square even lighter and more yellow.

After experimenting with this exercise using many different colors for the small center square, I noticed that the colors most susceptible to being “pushed around” have a considerable amount of gray in them, as do the taupe and grayish-green squares in the example above. It appears that our brain is more likely to alter the appearance colors that contain gray (low saturated colors) than pure colors (high saturated colors).

Take aways:

• You can expand your color palette just by placing the same colors on different backgrounds.
• Be aware that when you use a fabric with considerable gray tones in it, that fabric is likely to appear dissimilar when surrounded by different colors.

Playing With Optical Illusions

Exercise #1: Create a value progression using solids from your stash. Can you detect a gradated effect in the bars? Using Chevreul’s Rule #1, explain why this is happening.

Exercise #2: Cut two 2” squares of a color that has a medium value (i.e., a value that lies between the lightest lights and darkest darks). Now select two background fabrics, one very light and one very dark, and cut them into 6” squares. Place the 2” squares in the center of the 6” squares. Do you detect a difference between the 2” squares? Using Chevreul’s Rule #1, explain why this is happening.

Exercise #3: Look at the two small squares adjacent to one another in Image A below. They appear to be a soft lavender (a grayed-out purplish-red) and a grayish-green. Using Chevreul’s Rule #1 and Rule #2, explain why the small squares appear to look more similar when placed on the backgrounds. (Answer below Image B.)

Answer to Exercise #3:

• Since we want to make the  soft lavender square look more like the other small square, we need to darken it and give it a greenish cast. Therefore, we need to select a background that is lighter than the lavender square and the complement of green, which is red. I selected a pink background for the grayish lavender square.
• Since we want to make the grayish green square look more like the other small square, we need to lighten it and give it a lavender (purplish-red) cast. Therefore, we need to select a background that is darker and the complement of lavender (purplish-red), which is a yellow-green. I selected a dark yellowish-green background.

Conclusion

I hope this has given you a better understanding of how adjacent colors can impact one another in significant ways. I hope this description has also sparked new ideas about how you can create intriguing optical illusions simply by manipulating combinations of colors.

Learn more about manipulating color in the other articles in this series:
Article 1: Unlock the Secret of Color Interactions
Article 2: Make Your Quilts Glow with Saturation Contrast
Article 3: Add Sparkle to Your Quilts with Value Contrast
Article 4: Add Depth to Your Quilt Designs with Effective Transparencies

MJ’s newest in-person class titled “Color Play: Beyond Color Theory” explores the concepts she describes in this 5-part series. MJ also offers “Color Play” as a one-hour lecture or full-day in-person class that gives participants a chance to experiment with these concepts in more depth. Guilds can contact MJ at [email protected] for her availability. You can also check MJ’s website at https://www.mjkinman.com for a listing of classes that may be scheduled near you.

While you’re visiting her website, be sure to check out her collection of gorgeous gem patterns in her online shop.

Read our interview with MJ Kinman.