Color Vision: How We See Colour
Mix red, green and blue flashlights or choose one wavelength and see how your three cone types respond.
Drag the little handles on the flashlights up and down to change how bright each colour is, or pick one wavelength. Photons stream from the flashlights, mix on the wall and are seen by the eye.
About the Color Vision: How We See Colour
Free color vision: how we see colour. Mix red, green and blue flashlights or choose one wavelength and see how your three cone types respond. Drag, change the sliders and see the result live. No sign-up, works on phone and computer. Built for physics, the color vision: how we see colour runs instantly in your browser: change a setting or drag an object and the result updates at once, so you learn by trying things out rather than only reading about them.
Mix red, green and blue flashlights or choose one wavelength and see how your three cone types respond. Use it to explore physics ideas at your own pace, then check what you found against the key ideas further down this page.
How to use the Color Vision: How We See Colour
- Use the controls to change Light source, Red flashlight, Green flashlight, Blue flashlight, Wavelength. The simulation reacts instantly.
- Pick an option such as RGB flashlights, One wavelength to switch modes or load an example.
- Where you see a glowing handle, object, weight or atom, drag it with your mouse or finger. Everything responds in real time.
- Watch the readouts and graphs update as you experiment, and compare what you see with the key ideas below.
Things to try
- Make yellow from red and green.
- Make white light.
- Switch to a single wavelength at 580 nm.
Key ideas you can learn
- Your eye has three types of cone cells.
- Colours are made by mixing the three signals.
- Red + green light looks yellow.
- One wavelength of light can look like a mix of lights.
Where this is used in the real world
Screens, cameras, printers and colour-blindness tests all rely on how cones respond.
Who is this simulation for?
Physics students in middle school, high school and first-year university, teachers who want a quick demonstration for the projector, and anyone revising for exams. It works well for flipped classrooms because students can explore before the lesson.
For teachers: project it on the board, let students predict what will happen, then run it together. For students: change one thing at a time and write down what changes.
Frequently asked questions
How do we see colour?
Three types of cone cells respond differently to wavelengths, and the brain combines their signals.
Why does red plus green look yellow?
It stimulates the red and green cones the same way as a single yellow wavelength.
Is the Color Vision: How We See Colour free to use?
Yes. It is completely free, with no signup, no download and no ads inside the simulation. It runs in your web browser.
Does the Color Vision: How We See Colour work on a phone or tablet?
Yes. It uses touch as well as the mouse, so you can drag objects with your finger. A larger screen makes the controls easier to see.