Imagine a world without colour—just shades of gray, like an old TV show. Hard to picture, right? Colour is such a natural part of our lives that we rarely stop to ask how we actually see it. But the way we see colour is a fascinating mix of physics, biology, and a little brain magic.
Light, Eyes, and Brain: The Colour Dream Team
To understand how we see colour, we need to start with light. Sunlight, or white light, is actually made up of many colours—like a hidden rainbow.
When light hits an object, some wavelengths are absorbed and others bounce off. The ones that reflect are what we see.
A red apple reflects red wavelengths and absorbs the rest.
A blue sky? That’s sunlight scattered by air molecules.
A green leaf? It’s reflecting green and absorbing red and blue.
Our eyes catch those reflected wavelengths using special cells called photoreceptors.
The Role of Cones and Rods
Inside your retina (the back of your eye), you’ve got two types of photoreceptors: rods and cones.
Rods help you see in low light but don’t detect colour.
Cones are the colour experts. You have three types:
S-cones (short wavelengths) for blue
M-cones (medium wavelengths) for green
L-cones (long wavelengths) for red
Your brain combines signals from these cones to create the full spectrum of colours you see.
Did You Know?
🧠 The colour magenta doesn’t exist in the light spectrum. Your brain invents it by blending red and blue signals when green is missing!
A Quick History of Colour Perception
Ancient Greeks thought colour came from rays emitted by the eyes.
Isaac Newton was the first to show that white light splits into colours using a prism.
The modern understanding of colour vision began in the 19th century with the trichromatic theory—still the basis for how we explain cone function today.
Why Some People See Colour Differently
Colour blindness affects about 1 in 12 men and 1 in 200 women. It usually means one type of cone doesn’t work properly.
There are also rare conditions like tetrachromacy—mostly found in women—where a fourth type of cone allows them to see millions more shades than the average person.
Mini Q&A: Common Colour Questions
Q: Why does the sky look blue?
A: Because blue light scatters more in the atmosphere than other colours.
Q: Why do sunsets look red or orange?
A: At sunset, sunlight travels through more atmosphere, scattering blue light away and leaving reds and oranges behind.
Q: Can animals see colour?
A: Yes! But differently. Bees see ultraviolet, dogs see mostly blues and yellows, and mantis shrimp? They have up to 16 types of photoreceptors!
Seeing Colour in a New Light
I remember learning in school that colour was just “light bouncing off stuff,” but it didn’t click until I saw a prism split sunlight into a rainbow. That moment made me realize colour isn’t just out there—it’s something our brains create. It’s kind of wild to think that what I see as “blue” might not look the same to you at all.
So, How Do We See Colour?
It’s a beautiful collaboration between light, our eyes, and our brains. From the cones in our retinas to the way our brains interpret signals, seeing colour is a complex process that feels effortless. Next time you admire a sunset or pick out a ripe banana, take a second to appreciate the science behind the scene.
What’s your favorite colour—and do you know why you love it? Drop a comment and let’s talk colour!