[stephengillie]

TV cameras originally produced color by taking black-and-white video through 3 different filters, transmitting these as a bundle, and outputting these to the electron scanner. The colors didn't get mixed until after they hit the TV screen, as the photons were traveling to our eyes.

[ISL]

That's still how most imaging sensors work. Few, if any, actually parse the photon energy from within the imaging pixel itself.