Color is a fundamental aspect of visual perception and has three main characteristics: hue, saturation, and brightness. These three characteristics allow us to distinguish different colors and are important in fields like art, design, and science.
Hue
Hue refers to the dominant wavelength of light that determines the categorical color – red, orange, yellow, green, blue, or purple. It is what we typically mean when we refer to a “color” – the intrinsic wavelength of light that the eye perceives. For example, an orange and a lemon have different hues, as do a blueberry and blue denim jeans.
The visible spectrum of light contains wavelengths from approximately 390-700 nanometers. The longer wavelengths at the red end of the spectrum have lower energy, while the shorter wavelengths towards the violet end have higher energy. Our eyes contain special receptor cells called cones that can discriminate between wavelengths of light and allow us to differentiate hue.
There are six major hues that correspond to dominant wavelengths of the visible spectrum:
| Hue | Wavelength (nm) |
|---|---|
| Red | ~700 |
| Orange | ~610 |
| Yellow | ~580 |
| Green | ~510 |
| Blue | ~470 |
| Violet | ~390 |
These hues represent the pure spectral colors. All other colors we perceive are blends of these spectral hues. For example, turquoise is a mix of green and blue, while magenta is a mix of red and violet.
Saturation
Saturation refers to the intensity or purity of a color. It represents how much gray is mixed with the hue. Colors with high saturation appear vivid and intense, while colors with low saturation appear more muted and gray.
Saturation is determined by the ratio of pure hue to white light. At 100% saturation, a color contains only its pure hue with no white light added. Decreasing saturation means increasing the proportion of white light, which washes out or dilutes the color. For example, a fire engine red has high saturation, while a pale pink has lower saturation.
On a color wheel, saturation increases towards the outer edge and decreases towards the center. The center of a color wheel contains completely unsaturated grays, blacks, and whites. Moving outward, colors become more saturated and intense.
Here are some common color pairs that illustrate differences in saturation:
| High Saturation | Low Saturation |
|---|---|
| Burgundy | Pink |
| Forest green | Seafoam green |
| Royal blue | Baby blue |
Manipulating saturation is an important aspect of color theory and design. Less saturated, softer colors tend to be calming and subtle, while highly saturated colors are bold and dramatic.
Brightness
Brightness refers to the perceived intensity of a color from black (no brightness) to white (full brightness). It is also sometimes called lightness or value.
On a color wheel, brightness increases upwards from black to white. Adding white to a color increases its brightness, while adding black decreases its brightness. Brightness is independent from hue and saturation.
For example, both navy blue and light blue have the same hue and saturation, but navy blue has lower brightness. Pink (high brightness) and burgundy (low brightness) also differ mainly in brightness.
Some examples of color pairs that illustrate differences in brightness:
| High Brightness | Low Brightness |
|---|---|
| Pastel yellow | Gold |
| Seafoam green | Forest green |
| Sky blue | Navy blue |
In design and art, brightness contrasts can create depth, emphasize focal points, and direct the viewer’s eye. Darker colors recede into the background, while brighter colors come forward.
Color Models
There are various color models that can represent and visualize the relationships between hues, saturations, and brightnesses. Some common models include:
RYB Color Model
The RYB or red, yellow, blue color model is a traditional, subtractive color model based on paint pigments. The primary colors are red, yellow, and blue. Mixing two primary colors creates the secondary colors of orange, green, and purple. RYB was widely used by painters until the 20th century.
RGB Color Model
The RGB or red, green, blue model is an additive color model based on light. The primary colors correlate with the three types of cone photoreceptor cells in our eyes. Combining RGB light creates all the colors in the visible spectrum. RGB is used for digital displays, video, image sensors, and other electronic media.
CMYK Color Model
CMYK stands for cyan, magenta, yellow, and key (black). It is a subtractive model used in color printing, where cyan, magenta, and yellow inks are applied to absorb components of white light. Black (K) ink is added for greater contrast and intensity. By mixing the amounts of CMYK inks, a wide range of colors can be reproduced.
HSV/HSB Model
HSV stands for hue, saturation, value (brightness). HSB is hue, saturation, brightness. This model describes colors using properties that align with how our eyes perceive color. It is represented as a cone or hexagon shape, with hue rotating around a central axis. HSV/HSB models are widely used in color pickers, editing software, and other digital color tools.
Color Harmonies and Schemes
The characteristics of hue, saturation, and brightness allow us to create harmonic color combinations. Carefully selecting hues, saturations, and brightnesses that complement each other results in color schemes that are aesthetically pleasing and visually interesting.
Some examples of basic color harmonies include:
- Analogous – Colors next to each other on the color wheel, sharing similar hues. Example: yellow, yellow-green, green.
- Complementary – Colors opposite each other on the wheel. They create high contrast. Example: red and green.
- Split Complementary – A color plus the two colors adjacent to its complement. Example: blue, yellow-orange, orange.
- Triadic – Colors equally spaced around the color wheel. Example: red, yellow, blue.
In addition, color schemes can utilize tints, tones, and shades to systematically modify a color’s brightness and saturation:
- Tints – Lighter, brighter versions created by adding white. Example: pink is a tint of red.
- Tones – Variations created by adding gray. Example: mauve is a tone of purple.
- Shades – Darker versions created by adding black. Example: burgundy is a shade of red.
Mastering color combinations using principles like harmonies, tints/tones/shades adds visual interest and depth for aesthetically appealing designs and art.
Color and Vision
Our perception of color stems from special cells in our retinas called cones. There are three types of cones that respond preferentially to red, green or blue light. Signals from these cones are processed by our visual system to produce the wide range of hues we see.
A few key facts about the cones in our eyes:
- Cones are concentrated in the fovea, the central region of the retina.
- The “red” and “green” cones largely overlap in the wavelengths they absorb.
- Our sensitivity to light peaks in the green region at around 555nm.
- Women may have more types of red and green cones, allowing finer color discriminations.
Rods, the other light-sensitive cells in our retinas, do not detect color at all. This explains why colors appear muted in low light, where rods dominate vision.
Color Blindness
Color blindness (color vision deficiency) is the decreased ability to perceive differences between some colors. It often involves limited sensitivity to red, green or blue light due to abnormalities in the cone cells.
The most common form is red-green color blindness, where people have difficulty distinguishing between red and green hues. This arises from abnormalities in the “red” and “green” cones. Red-green deficits make up over 99% of color blindness cases.
Less common forms are blue-yellow color blindness (trouble with blue and yellow) and total color blindness (seeing only in shades of gray). The severity can range from mild to complete inability to see color.
Color blindness is much more prevalent in men than women, as the genes for the red and green cones are on the X chromosome. About 1 in 12 men and 1 in 200 women have some form of color vision deficiency.
Applications of Color Science
Understanding the visual perception of color has broad applications in many fields. Here are some examples:
Digital Displays
Displays use the RGB color model to create the colors we see. Engineers combine precise mixtures of red, blue, and green light to accurately render images and videos.
Printing/Design
Printers mix cyan, magenta, yellow, and black inks following the CMYK model to reproduce color artwork and photos on paper. Graphic designers manipulate hue, saturation, and brightness to create appealing designs.
Lighting
LED and other light fixtures mix red, green, and blue elements to create white light or any other hue. The spectrum of the light source impacts how colors appear.
Textiles/Dyes
Fabric dyes and pigments selectively absorb and reflect portions of the visible spectrum. Chemical modifications tune the colors across any hue, brightness, and saturation.
Vision Testing
Optometrists use color vision tests to assess an individual’s ability to detect differences in hue, saturation, and brightness to diagnose deficiencies.
Color Matching
Engineers develop algorithms to automatically match colors between devices and applications. This allows consistent color appearance across platforms.
Overall, the three attributes of hue, saturation, and brightness serve as the foundational language for describing and controlling color across science, art, and technology.
Conclusion
In summary, the three main characteristics of color are hue, saturation, and brightness. Hue determines the dominant wavelength we perceive as red, green, orange etc. Saturation describes the intensity and purity of a color. Brightness represents the perceived luminance or intensity of a color from black to white. Understanding these three attributes allows us to differentiate all the colors we see. They provide a framework to describe colors, create harmonies and schemes, and reproduce colors technologically. Color science applies principles of hue, saturation and brightness to fields like displays, printing, lighting, and vision testing.