How cameras see color: RGB vs RGBW, Bayer vs Fuji X-Trans, Purple isn't real?!

Tony gets mega geeky as he digs into the science of color. He describes how our brains map colors to wavelengths of light, how purple is non-spectral and literally a figment of your imagination, how the rods and cones of your eye detect color in almost exactly the same way as your camera's sensor. He also describes the difference between a traditional Bayer filter and the X-Trans filters that some Fujifilm cameras use (like the X-T3 and X-H1).