Opponent Process

Why doesn’t pink appear as a distinct wavelength in the visible spectrum, and how does the human brain create the perception of pink from mixed red and blue light?

Pink and its close cousin magenta is a perfectly real colour to your brain, but it doesn’t work like the colours of a rainbow. The two‑part secret: pink has no single wavelength, and your brain makes it up when it sees a mix of red and blue light. Why pink...