I don't really understand primary colours as it relates to vision. Cone cells have a range of sensitivities that vary by person and colours are mapped to wavelengths.
So something reflecting radiation with a wavelength of 470 nanometres looks blue, and something reflecting radiation with a wavelength of 660 nm looks red. Yellow, orange etc still exist at specific wavelengths, but having an extra cone cell that is very sensitive red and green means you could better see the difference between orange at 600 nm and orange at 601 nm, and if you combined that light with blue at 470nm, you'd still get brown but you'd be much better at distinguishing between brown (600nm orange+blue) and brown (601nm orange+blue).
I don't really understand primary colours as it relates to vision. Cone cells have a range of sensitivities that vary by person and colours are mapped to wavelengths.
So something reflecting radiation with a wavelength of 470 nanometres looks blue, and something reflecting radiation with a wavelength of 660 nm looks red. Yellow, orange etc still exist at specific wavelengths, but having an extra cone cell that is very sensitive red and green means you could better see the difference between orange at 600 nm and orange at 601 nm, and if you combined that light with blue at 470nm, you'd still get brown but you'd be much better at distinguishing between brown (600nm orange+blue) and brown (601nm orange+blue).