What Is Color, and How Do We See Color?

Every object we see has color, and it is an essential part of how we interpret the world. But color isn’t an inherent quality of the objects in front of us. Consider a classic red apple. If you look at it under a blue-tinted light, it will appear somewhat blue, and if you look at it under no light, you won’t see anything. So, what color is the apple?

As it turns out, color is simply a perception of energy and specific wavelengths of light that reach our eyes. It can also vary based on the biology of a person and how their brain receives signals, so two people may not see an object as the exact same color. Let’s take a closer look at what color actually is.

Why Does Color Matter?

Color does more than make something red, blue, or pink. It influences our perceptions and moods and plays a significant psychological role.

A warm-toned photo feels uplifting or joyful, while a cool one is serene or depressing. We see specific colors as eye-catching— some may spur us to purchase. Think about your favorite brands — their logos and imagery are carefully selected to incite specific buying habits and make you associate particular traits with the company.

When it comes to products, color can make us more attracted to an item. Bright candies are colorful and fun, while a ripe red tomato may look remarkably fresh and juicy. Many manufactured products must maintain the same color throughout production to increase buyer confidence or improve identification. For instance, each pill of a specified drug must match the previous one, and each can of paint should be mixed to the expected color.

The psychology of color perception is an integral part of our everyday lives.

How Do We See Colors?

The way we see colors could be more complex. The physics of color perception involves energy wavelengths, reflections, and signals zapping back and forth in our brains. So, what is color in science terms?

You may recall from elementary school that the rainbow follows a specific color pattern you might have learned as "ROYGBIV." This pattern corresponds with energy wavelengths. Red has the longest wavelength, while violet has the shortest.

When sunlight strikes an object, some materials absorb specific wavelengths. Wavelengths that are not absorbed are reflected. The reflected light then reaches our eyes, causing us to see the reflecting item as a particular color.

How Does Your Eye Influence Color Perception?

The way we see colors could be more complex. The physics of color perception involves energy wavelengths, reflections, and signals zapping back and forth in our brains. So, what is color in science terms?

The color-perception process doesn’t end when the light reaches your eyes. It involves the stimulation of rods and cones, which send a signal to the brain of what color we perceive. Cones and rods are activated by different types of colors and lighting scenarios.

Due to variations from person to person and differing environments, the perception of color can vary wildly. An object will look different in dim light versus bright light, and some people can have cones that don’t function normally, causing color-blindness. Even with properly working cones, your brain may interpret signals slightly differently from the person next to you.

Here's how the entire process works.

1. Light hits an object.
2. Specific lightwaves reflect off some materials and get absorbed by others.
3. That reflected light enters the eye, where the lens focuses it toward cones and rods.
4. The cones and rods react to the light and encode it into signals the brain can read.
5. These signals get sent to the brain through a complex network of neurons and synapses. The brain then perceives those signals as color.

With all these moving parts, an object that reflects specific wavelengths won't always look the same between viewers, so finding unbiased color measurements is essential.

How Cones in Our Eyes Affect Our Vision

Those cones and rods are crucial to making sense of vision and light. Once light hits your eyes, the lens of your eye focuses it onto those light-sensitive cells, rods, and cones, each of which picks up different wavelengths of energy. Rods work best in dim light, while cones specialize in specific ranges of colors.

• L-cones: L-cones, or red cones, make up 64% of our cones and are sensitive to the longer wavelengths that make red light.
• M-cones: Making up 32% of cones in the eye, M-cones, or green cones, respond to medium-wavelength, or green, light.
• S-cones: S-cones are also called blue cones since they pickup shorter wavelengths like blue. They only make up about 2-7% of total cones.
• Rods: Rods work in low light and help us see at night without color reception. They also play into our peripheral vision.

If you're wondering what color humans see best, look at the M-cones. As it turns out, green is right in the middle of the spectrum and is the easiest color to see.

What Is Color Theory?

Color theory combines much of the information about color into a design tool. You're probably familiar with the color wheel, which arranges visible colors by their natural electromagnetic wavelengths. For instance, the color wheel moves from red, the longest, to violet, the shortest.

There are several ways to mix colors, such as additive and subtractive methods, but they usually work with primary, secondary, and tertiary colors. Primary colors are those that can't be created by mixing other colors. They are red, blue and yellow. We don't have a color receptor for yellow, but we do have one for green. So, how do we see yellow?

There's a reason we associate yellow with sunlight and other bright lights. That's because yellow is one of the brightest colors. Detecting yellow requires our brains to combine the excitement levels of red and green cones.

Factors That Influence How We See Color

In addition to intrinsic or taught color perception, numerous additional variables influence color vision:

• Lighting: Light has a significant impact on color perception. The hue of light influences the color that your brain perceives. 
• Retinal fatigue: Your eyes can get fatigued quickly. When you gaze at an object for more than a few seconds, chemicals in your eyes decrease and transmit inaccurate signals to your brain.
• Age: As you get older, your ability to see color fades. Fortunately, color vision is not only innate but also an acquired skill.
• Backdrop effects: A phenomenon known as simultaneous contrast occurs when the backdrop against which we assess color impacts our eyes' ability to detect the color correctly.
• Poor color memory: Humans have terrible color memory. It's futile to simply gaze across the room to see if two colors match.

Environmental Influences on Color Evaluation

What are the implications of these environmental difficulties for color analysts and comparisons? You must grasp the effect of light on color perception, be aware that your eyes are easy to deceive, and use the workarounds developed by color science engineers:

• A weary eye cannot make effective color judgments, particularly after being overstimulated by a bright hue. Rest your eyes before observing, examine quickly, and rest again before the next color assessment.
• Always be mindful of your surroundings. Hues can appear different depending on the surrounding colors. When assessing color, utilize a light booth to verify that nothing obscures your vision.
• Determine what sort of light is illuminating your color. A light booth can assist you in managing the illumination and maintaining uniformity.
• To record color information, use color measuring equipment. A colorimeter or spectrophotometer detects reflected light from the desired sample region, and the sample is not influenced by any surrounding colors. 

The Mathematics of Color

Subjectivity in color perception poses a significant challenge for businesses, leading to production delays, material waste, and quality control issues. Manufacturers have embraced a mathematical approach to color specification to attain color accuracy and consistency.

The CIE XYZ color space, created in 1931, is the foundation for this technique. It defines colors in a three-dimensional space using red, green, and blue values. Building on this basis, other models, such as CIELAB (1976), included characteristics such as luminance (L), red-green (A), and blue-yellow (B) axes for more complex color representation. Another model, CIE LCh, includes lightness, chroma, and hue to provide even more detailed color descriptors.

Colorimeters and spectrophotometers are specialized equipment used for objective color measurement. These gadgets offer exact digital representations of color, eliminating subjectivity. In essence, mathematics provides an objective language for color, allowing organizations to achieve uniform color replication while minimizing costly mistakes.

Measuring Color

So, with all this science in mind, how do we convert that information into usable data? Let's start by looking at that system of rods and cones. Each type of cone is responsible for one color. That means that to recreate specific colors, we have to manipulate those wavelengths. Whatever configuration they're in, the cones and rods will respond accordingly. That's how TV and mobile device screens can recreate colors — by putting three different lights — one red, one blue, and one green — into a small area on a screen called a pixel.

Of course, before manipulating these colors, we have to measure them and identify target colors, which is where a spectrophotometer comes into play.

A spectrophotometer is a tool that converts subjectively perceived colors into objective numbers that are used in design and communication. A spectrophotometer uses a L*a*b color space, which identifies the relationships between certain aspects of color and assigns a value between 100 and -100 to each one. Combining these values creates a specific number that corresponds to an exact color.

• L: The "L" value looks at lightness and darkness with values that represent pure white and pure black.
• a: The "a" value looks at where a color lies on a red-to-green spectrum.
• b: Finally, a "b" value measures the color between yellow and blue.

We can view L*a*b color measurements as though they occupy three-dimensional space. Picture the L range as a pole going right down the middle of a box. The a and b values would be reflected as the x- and y-axis of a flat plane directly in the center of the box, perpendicular to the L range. As the color becomes darker, it moves toward the bottom of the box, and as it becomes more red, blue, green, or yellow, it moves toward the corresponding edges.

Once you have this number, you can find it again later without subjectivity.

Color Measurement Devices by HunterLab

To get these measurements, you need the right tool for the job. Spectrophotometers from HunterLab can measure everything from loose powders and meat patties to translucent liquids and plastic bottles. Each material reflects light in its own way, and using a suitable spectrophotometer is critical if you want to get the correct color data.

With a wide array of products and a history of accuracy, HunterLab is there for you. Contact us today to learn more about measuring and working with color.