[ELI5] What determines which color an object is?



[ELI5] What determines which color an object is?

In: Physics

There are two main ways color is determined: by colors absorbed or by colors reflected.


By colors absorbed is much more common. Everything colored contains substances called pigments or dyes that absorb certain colors. The colors of light that are not absorbed by the pigments or dyes are the ones that reach your eyes and tell you what this object looks like. The exact colors of light absorbed depend strongly on the actual shape/structure of the pigment or dye. For example, the molecule chlorophyll in plants absorbs both red and blue light, but does not absorb green. The green light passes through and reaches your eye, so you see the leaf as green.


Color can also come from structures in the material that reflect and strengthen a particular color. This is called “structural color”. Good examples of this include bird feathers and butterfly wings. The Blue Morpho butterfly has tiny structures in its wings that amplify blue light, making its wings appear blue. Birds commonly have feathers that appear black as a background, but also have structural pigments that scatter green or blue light, resulting in a green or blue sheen on the feathers.

Edited because rules: Most educated people will talk about the spectral characteristics of light additive or pigment additive color wheels, but that’s the physics of light while color perception is specific to the biology of the eye and the brain. The eye doesn’t send color info to the brain like a camera does, it sends contrast information which the brain uses to determine what color something is.
Zogg from Betelgeuse explains it better than I can in Earthlings 101 ep 12. https://youtu.be/hZED73seTQE

Tricky question.
I agree with previous answers about light….BUT “Color” is very subjective .

It’s only available to the receptors present.
What does red look like to a “color” blind person they still see a color…just not your color…..

Insects see in UV spectrum, flowers glow under the UV light/UV cameras as bright targets…..but to us its pure white because we lack the visual receptors.

Your sensory receptors LIMIT your senses. Imagine if you could see all the EM spectrum radio waves to xray…..or could hear every sound…..
Your brain would melt.