Light is part of the electromagnetic spectrum, according to modern physics.
- Shares wave properties with X-rays, microwaves and radio waves, including dispersion
- Visible light spans wavelengths from 400 nm to 700 nm
- Quantum physics attributes particle properties to light. Refraction is better explained by this theory.
Color
Color is a construct in the brain. It doesn’t correspond to a physical phenomenon.
- Mixing light waves of different wavelengths produces the perception of different colors
- A few narrow wavelength bands are perceived as distinct colors, called primary colors
- Primary colors are orthogonal to each other
- Mixing primary colors produces the secondary colors we perceive
- Red, green and blue are the most common primary colors, but not the only ones
Why RGB
The human eye has three types of cone photoreceptors, each maximally sensitive to different wavelengths.
- L cones respond best to ~560 nm (red light)
- M cones respond best to ~530 nm (green light)
- S cones respond best to ~420 nm (blue light)
Any visible color is your brain’s interpretation of signals from these three cone types firing at different intensities. RGB primaries are chosen because they align with cone sensitivity. Each wavelength band stimulates a different cone type, making them orthogonal. You can recreate any visible color by combining red, green, and blue light in the right proportions, without needing the full spectrum.