Don Romano (alt)Wavelength response of the human eye versus the CIE 1931 XYZ colour space (best imitation of human eye possible at the time) versus TCS34303 XYZ sensor.
That sensor is hard to get hold of if you're not a major manufacturer. Much harder than a generic RGB sensor, which is a shame, because those have no colour accuracy. An XYZ colour sensor is literally the most colour-accurate sensor you can get, because XYZ is "RGB for humans" and every other colour space has a mapping to it.
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