R-G&B

R-G&B is a (another) science museum exhibit (it is actually stolen directly from an Exploratorium 'zibbit [re]constructed by Peter Stephens: "...it was Richard Gregory's idea built by Claire Pillsbury and then re-built by me.") It purports to allow the user to match a yellow color by mixing red and green and then adjusting the brightness of the yellow to compensate. The idea is that people arrive at different settings, thus showing that none of us sees things in exactly the same light.

It is implemented using LEDs with pulse-width-modulation to adjust their intensity. The Yellow reference on the right is very close to the familiar sodium street lamp at 592nm. The Red is 627nm and the Green is 520nm. It is interesting to note that the red output needs to be much brighter than the green in order to achieve a good balance.

It remains to be seen how well this works as I've yet to test it on very many unsuspecting users. Should it really work the button at the top right allows the settings to be recorded for later downloading and mungling.