Exploring Trichromacy through Maxwell's Color Experiment (2023)

Summary

Exploring Trichromacy through Maxwell's Color Experimentby Koh Teraiwith the guidance of Professor Brian Wandell for Psych 221: Image Systems Engineering at Stanford UniversityLast Updated: 19:30 Saturday, December 30, 2023 (PST)We can create most of the colors we see daily using just three colors. For example, you may have heard of R, G, B — Red, Green, Blue — to express many colors. This understanding is fundamental to how we display color on monitors and how we print color.But why three colors? Why not two or four or five? And how did humans discover that our eyes can "see" different colors by combining just three colors?Today, this phenomenon is explained through the trichromatic theory, also known as the Young-Helmholtz theory, attributed to Thomas Young and Hermann von Helmholtz in the 19th century.Less known to the development of trichromacy is another scientist —James Clerk Maxwell's contribution to the development of the theory.In this piece, we explore the early experiments that led to the development of trichromacy through the less-celebrated, less-attributed James Clerk Maxwell's ingenious experiment to discover and prove the trichromatic theory.Introducing the ApparatusOur first step in retracing Maxwell's path is familiarize ourselves with the tool he created to conduct his experiment.The tool consisted of a box around 6x3ft with a mirror, prisms, and lens, with a viewing hole to allow viewers to look inside the box.Note: The figure not to scaleAs a thought experiment, imagine shining a full spectrum of white light from the viewing hole at the bottom. The white light would be dispersed through the two prisms, creating a pure spectrum to the left, revealing all the wavelengths of visible light.Now imagine that we create slits on the left side to cover up most of the pure spectrum other than a specific section. We would only see a particular spectrum region on the other end.Imagine that we shine light from the other direction. But we will only let a mono...