In the previous article, we broke down the three dimensions of color: hue, saturation, and value. You may already be able to precisely describe "what color this is." But description is only the first step. The real challenge is: when multiple colors are placed together, what is the relationship between them?
This is the problem the color wheel solves. The color wheel organizes the colors of the hue wheel into a structure, revealing their relationships — which colors are "family," which are "opponents," and which are mixed "descendants." To understand this structure, we must start with three foundational concepts: primary, secondary, and tertiary colors.
What Is the Color Wheel?
The color wheel is a circular arrangement of hues. It was first drawn by Newton in 1666 after he decomposed sunlight with a prism, and was later developed by Goethe, Itten, and others into the various versions we see today in art textbooks and design software.
The value of the color wheel is not that it "looks nice," but that it visualizes color relationships. Once colors are arranged in a circle, distance represents relationship: adjacent colors are close, opposite colors are opposed, and equally spaced colors form balance. All classic color schemes — complementary, analogous, triadic, and split-complementary — are derived from the distance relationships on the color wheel.
💡 Key Insight: The color wheel is not unique. The RYB wheel (art), RGB wheel (screen), and CMY wheel (print) share a similar structure, but their primary colors are in different positions. This article uses the most general RYB wheel as the main framework, while noting its differences from CMY.
Primary Colors: The Starting Point That Cannot Be Split
Primary colors are the most basic colors on the color wheel. They cannot be obtained by mixing other colors. All other colors are mixed starting from the primaries.
The Three RYB Primaries
In traditional art and color education, the three primaries are:
- Red
- Yellow
- Blue
They are evenly spaced around the wheel, about 120° apart. On the wheel, they form an equilateral triangle — the "foundation" of the color wheel structure.
But Primary Colors Are "Relative"
Here we must clarify a common misunderstanding: there is no absolute set of primary colors. The definition of primary colors depends on the medium and color model you are using.
Why does this difference exist? Because the essence of "primary colors" is the base colors that cannot be further decomposed in that medium. Screens emit light, and red, green, and blue light cannot be mixed from other lights. Printing relies on ink absorbing light, and cyan, magenta, and yellow inks cannot be mixed from other inks. RYB, meanwhile, is the "most convenient set of three tubes of paint" summarized from centuries of painter practice — it is not perfect, but it is practical enough.
Where Primary Colors Are Used
- Painting and color mixing: Using three tubes of red, yellow, and blue paint to mix most colors is the basic skill of watercolor and oil painting.
- Color education: Primary colors are the starting point for understanding color mixing, and almost every color course begins here.
- Color scheme derivation: Knowing where the primaries are allows you to derive secondary and tertiary colors, and then build a complete palette.
Secondary Colors: The First Mix of Two Primaries
Secondary colors are colors obtained by mixing two primary colors in equal amounts.
The Three RYB Secondaries
On the RYB wheel, the three secondary colors sit between two primaries, exactly at the midpoints of the three sides of the primary triangle:
- Red + Yellow = Orange
- Yellow + Blue = Green
- Red + Blue = Violet
Putting the three primaries and three secondaries together gives the wheel six colors: red, orange, yellow, green, blue, and violet. These six colors form the basic skeleton of the color wheel and are also the color names most commonly used in everyday language.
Equal Mixing Is the Key
The definition of secondary colors emphasizes "equal amounts." If the mixing ratio differs, the result is not a standard secondary color but an intermediate color leaning toward one primary. For example, more red and less yellow gives red-orange, while more yellow and less red gives yellow-orange — they are still on the wheel, but are no longer the "exact midpoint" secondary colors.
💡 Practical Note: With real pigments, mixing equal amounts of red and yellow does not necessarily produce a vivid orange, because the pigments themselves contain impurities. This is why professional painters keep multiple reds and yellows — cadmium red with cadmium yellow gives a warm orange, while alizarin crimson with lemon yellow gives a cooler orange. The theoretical secondary color is an ideal state; actual mixing requires fine-tuning based on pigment characteristics.
Where Secondary Colors Are Used
- Building the six-color wheel: Primaries + secondaries = the six-color base wheel, the starting point of all color schemes.
- Transition and harmony: Secondary colors naturally "connect" two primaries, making them suitable for gradients and transitional colors.
- Identifying complementary relationships: On the wheel, opposite primaries and secondaries are complementary, such as red and green, yellow and violet, blue and orange.
Tertiary Colors: Mixing a Secondary with a Primary Again
Tertiary colors are colors obtained by mixing a primary color with an adjacent secondary color.
The Six Tertiary Colors
On the RYB wheel, each primary and its adjacent secondary can be mixed to produce a tertiary color, for a total of six:
- Red + Orange = Red-Orange
- Yellow + Orange = Yellow-Orange
- Yellow + Green = Yellow-Green
- Blue + Green = Blue-Green
- Blue + Violet = Blue-Violet
- Red + Violet = Red-Violet
Putting primaries, secondaries, and tertiaries all together gives the wheel twelve colors. This is the most classic twelve-color wheel and the foundational structure of Itten's color theory.
The Special Value of Tertiary Colors
Tertiary colors sit between primaries and secondaries on the wheel. They are not as "pure" as primaries, nor as "exact" as secondaries, but it is precisely this intermediate quality that makes them the most practical colors in color schemes.
- Reducing conflict: When two complementary colors are too harsh together, using a tertiary color as a transition makes the composition much softer.
- Adding depth: Tertiary colors expand the wheel from six colors to twelve, doubling the "vocabulary" available for color schemes.
- More natural: Pure primaries or pure secondaries rarely appear in nature; most colors are tertiary — which is why compositions built with tertiary colors feel more realistic and more pleasing to look at.
The Three-Layer Structure at a Glance
Organizing primary, secondary, and tertiary colors by layer makes the skeleton of the color wheel very clear:
3 + 3 + 6 = 12. The twelve-color wheel is not drawn arbitrarily — it is the natural result of the mixing logic. Understand these three layers, and you understand why the color wheel looks the way it does.
Relationships on the Color Wheel: From Structure to Color Schemes
Primary, secondary, and tertiary colors are not just categories — their positions determine the relationships between colors. The most commonly used relationships on the color wheel are all based on this three-layer structure:
Complementary Colors
Two colors directly opposite each other on the wheel, 180° apart. For example, red and green, yellow and violet, blue and orange. Complementary colors have the strongest contrast and are great for visual impact, but large areas can be harsh on the eyes.
Analogous Colors
Colors adjacent on the wheel, within 30° of each other. For example, red, red-orange, and orange. Analogous schemes are harmonious and unified, and are the easiest color schemes to start with.
Triadic Colors
Three colors equally spaced on the wheel, forming an equilateral triangle. The most typical examples are the three primaries themselves (red, yellow, blue) or the three secondaries themselves (orange, green, violet). Triadic schemes have both contrast and balance, and suit scenarios that need rich color.
Split-Complementary Colors
Choose one color, then choose the two colors on either side of its complement. For example, red + yellow-green + blue-green. This scheme retains the contrast of complementary colors but is softer and more layered than pure complementary.
“The color wheel is a map. Primary colors are cities, secondary colors are roads, and tertiary colors are the neighborhoods connecting cities and roads. Understand this map, and you can find the shortest path between colors — and know when to take the long way around.”
The Differences Between the RYB, RGB, and CMY Wheels
As mentioned earlier, the color wheel is not unique. The three main wheels share a similar structure, but their primaries are in different positions, which also changes their secondaries and complementary relationships:
Notice an interesting phenomenon: the secondaries of RGB are exactly the primaries of CMY, and the secondaries of CMY are exactly the primaries of RGB. This is not a coincidence, but the mathematical result of the complementarity between additive and subtractive color. This is also why the relationships "flip" when colors on screen are converted to print.
Practical Selection Guide
- Learning to paint: Use the RYB wheel to understand the mixing logic of primary, secondary, and tertiary colors — this is the foundation of art.
- Doing design: Use the RGB or HSL wheel to pick colors, but the principles of color relationships (complementary, analogous, triadic) are the same as in RYB.
- Doing print: Use the CMY wheel to understand ink mixing, and note that complementary relationships on the RGB wheel change in CMY.
- Teaching color: Start with the twelve-color RYB wheel — it is the most intuitive and best matches the intuition of "mixing."
- Building color schemes: First determine a primary hue, then choose a complementary, analogous, or triadic relationship based on wheel distance, and finally use tertiary colors to harmonize.
In the next article, we will move from the structure of the color wheel to practical application: color contrast and color scheme principles — how to use complementary colors without being harsh, how to keep analogous colors from becoming monotonous, and how to use value and saturation to adjust relationships on the wheel. The color wheel has given you the map; the next article teaches you how to walk.