Response spectra of human cones: https://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Cone-fundamentals-with-srgb-spectrum.svg/1000px-Cone-fundamentals-wit

Response spectra of human cones: https://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Cone-fundamentals-with-srgb-spectrum.svg/1000px-Cone-fundamentals-with-srgb-spectrum.svg.png https://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Co... The medium ("green") and long ("red") cones are pretty close and similar. It's interesting that the diversity of reds and greens we experience are computed from two mostly-overlapping signals having peak responses at roughly "leafy green" and "sunny yellow".