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Science of Color

Wacky professor of chemistry experiment performed laboratory with lot of smoke

Read time: 6 minutes

We rely on color every day. Colors impact emotions, stimulate our senses, and influence our actions.

Color is a powerful communication tool and can be used to prompt, influence, and even sway individuals. It can also help us to remember objects, influence purchases, and spark emotions.

All of these strategies to engage with people rely on people seeing color in a common way.

That's why understanding the science of color can help us effectively communicate with each and every one.

Color is both consistent and personal.

In my last post — Personal With Color — I shared that English physicist and mathematician, Isaac Newton, was stuck at home during the plague and began a series of experiments with sunlight and prisms.

He concluded that clear white light was composed of seven visible colors.


Since Newton’s discovery, color has been researched, analyzed, and measured, leading to our current understanding of how we see, use, and rely on color.

Color can be reproduced, creating a common language.

Color is carefully monitored with systems of measurement, which help us analyze, track, and reproduce color. We benefit from these systems in how we live, work, and play.

In 1931, the RGB (red, green, blue) color space and XYZ color space model shown below were created by the International Commission on Illumination (CIE).

These models are still used in setting industry color-standards in products such as image scanners, digital cameras, monitors, TV screens, film printers, computer printers, offset printing presses, and similar media types.

Illustrated in the chart below, the human eye with normal vision has three kinds of cone cells that sense light, having peaks of spectral sensitivity in short ("S", 420 nm – 440 nm), middle ("M", 530 nm – 540 nm), and long ("L", 560 nm – 580 nm) wavelengths.

A line chart illustrating the eye's sensitivity to different wavelengths of light.


A gradient chart illustrating purples and blue light are higher frequency with shorter wavelengths while yellow and red lights are lower frequency with longer wavelengths.

Our eyes can only see purples, blues, greens, yellows, oranges, and reds. And although we can see colors that have a closer wavelength to them, we still cannot see ultraviolet (UV) and infrared (IR) colors. Since UV rays are dangerous for our eyes, they will actually filter them from view due to our eye lens. As for IR colors, they don’t generate enough energy for our eyes to see beyond red, so we are blind to these colors and need special protective glasses to see them.

Five unique people. Illustration.

We are all uniquely created.

There are two types of photoreceptors in the human retina:

Rods and cones.

Like fingerprints, the rods and cones in our eyes are uniquely our own. The image below shows the arrangement of L (red), M (green), and S (blue) cones in the retinas of different human subjects.

Nine different people's retinas showing variation in rods and cones.

Because genetically our eyes are uniquely our own, the CIE defined a color-mapping function called the standard (colorimetric) observer to represent an average human's chromatic response within a two-degree arc inside the fovea, a small area in the retina of the eye where visual sharpness is the highest.

This angle was chosen in the belief that the color-sensitive cones resided within the two-degree arc of the fovea.

We have a variety of red, blue, and green sensors in the back of our retina. The variety and proportions are due to genetics.

Different people can sense color differently.

However, these guides help create a common language.

Most of the color sensors in the eye are within the center area.

If you put your arm and thumb up, that’s the area where your eye is most sensitive to color.

Outside that area, the colors become mixed.

This is why we see small and large amounts of color differently, like a wall painted in a room.

Colors in the peripheral affect what we see.

This commonality can be further described by chromaticity.

Chromaticity is an objective specification of the quality of a color regardless of its luminance (intensity of light emitted from a surface). Chromacity consists of hue (red, orange, yellow, green, blue, purple) and colorfulness (chromatic intensity).

A graph illustrating the temperature of different colors.
The CIE 1931 xy chromaticity space, also showing the chromaticities of black-body light sources of various temperatures, and lines of constant correlated color temperature. Source:

Light plays a key role in perception.

We see color that is reflected off surfaces. The other colors from the light are absorbed into the surface of the object.

Light sources create a spectrum of light, shined on different things (spectral filter). Light is scattered, diffused, reflected, absorbed, and transmitted. Our eye resolves what light is reflected and this is what we see.

This concept can be illustrated by looking at leaves changing color in the fall. In autumn, leaves go through color changes due to the chemicals inside.

A fan of leaves varying in color between green to yellow to orange to red.
Photo by Chris Lawton on Unsplash


The chlorophyll in the leaf collects energy for the leaf.

It absorbs blue, violet, and red light. Although the leaf doesn’t use green light, and green light is reflected and is what we see throughout the year.

Until fall that is.

During that period, we see that the leaf doesn’t need the green light. As the leaf dies, we see the carotenoids. These pigments produce bright yellow, red, and orange colors in plants, vegetables, and fruits.

This is also where carrots got their names.

As the leaf continues to die, chlorophyll and the carotenoids stop working, and we see anthocyanins — red, purple, and blue — as a result.

These colors are in a number of foods that give red, purple, and blue plants their rich coloring.


Wonder how we see color?

Look at the flying geese image for 30 seconds, blink a couple of times and look at a blank wall.

What do you see?

Do you see the opposite colors?

Different parts of the retina were fatigued when staring at those colors. When that happens, they “switch off” or go temporarily “blind,” and that creates an “after image” with the opposite or complementary colors.

Science helps us use color consistently.

Designers use color systems to implement and govern brands, as well as color guides such as the Pantone systems and industry trade tools such as AIM Contrast tools.

At Unity, our clients can feel confident that their brand will be accurately reproduced online, and we use these tools to monitor and assure our websites are accessible not from just a usable standpoint, but a visual lens as well.

On The Horizon

We have one more article to share with you in our Personal With Color series but, in the meantime, make sure you get caught up on parts one and two of our series — Personal With Color and The Art of Seeing.

Stay tuned for more soon!