Why is the sun used as a perfectly “full-spectrum” color source when compared with other lights? If you look at the graph it doesn’t represent each frequency (color) equally. Why is it then a perfect source? Does it make every color “visually equal to the human eye” just because we’re accustomed to it? If we got accustomed to an equally distributed (in frequency) light source, then would colors eventually seem more equal?
Not accustomed, but evolved. Our eyes developed to see light that was available, and that generally came from that big glowing orb in the sky.
The Sun’s spectrum is actually quite ragged: http://www.rfcafe.com/references/electrical/images/ASTM%20G173-03%20Reference%20Spectra.gif
Yup. You’re thinking the hole in the ground was perfectly shaped for the puddle when in reality the puddle just filled in the shape the hole already had.
This. Way nice analogy, by the way!
I stole it from Dawkins.
I understand it is original to Douglas Adams.
It’s really both. Our brain adjusts our color perception so the available illumination looks “white” even if it has a red or blue tint to it. Light from an incandescent bulb has a lot more red (less blue) than sunlight, but if you sit in that light for a while, it starts to look neutral and white.
As a matter of fact, if you’re outside at dusk, and look at the window of a room lit by fluorescent lights, you’ll be shocked at how green it can look.
I strongly suspect that most or all of that adjustment takes place in the retina rather than in the brain, although it has been said (with some justice) that it might very well be most appropriate to consider the retina as a part of the brain, despite its anatomical separation from the rest. In any case, there is a fairly complex neural network within the retina itself, and that is probably what is doing the adaptation work here.