The Science of Color

The Science of Color

TopicsThe SpectrumColor Mixing – Additive and SubtractiveColor Mixing – Pointillism and the limitations of the human eye“Warm” and “Cold” colors versus what we observe in nature

What is 'light'?What is 'color'?What forms of light are there?Prism, gratings

What is 'light'?What is 'color'?What forms of light are there?Prism, gratings

ChallengeHot filament vs colder filament – which is which?

ChallengeHot filament vs colder filament – which is which?We like to think of blue as a 'cool' color (ice), and of red as a 'warm'color (fire). However, ice is blue because it reflects blue light fromthe sky, and fire is red because the embers are red hot.

Orion constellation: stars Betelgeuse vs Rigel

“Colory Theory” began way back with NewtonNewton was interested in the phenomenon of “fantasy”,the tendency to continue “seeing” a bright light after the light goesaway, even if you close your eyes. To test this effect, he lookedwith one eye directly at the Sun for an extended period of time untileverything appeared pale red or blue. He went indoors, and after“ye motion of ye spirits in my were almost decayed”, he closed thateye and found that the bright spot seemed to reappear. When heopened that eye he everything looked red or blue again. Incredibly,he seems to have undertaken this experiment without consideringthe possibility of permanently damaging his eyesight. Only when the spots andoptical “fantasies” persisted did he become worried, and he shut himself up intotal darkness for several days before they finally subsided.In his subsequent optical experiments Newton was more cautious about looking atdirect sunlight, but he was still remarkably reckless with his eyes. About a yearlater he wedged a blade “betwixt my and ye bone as near to ye back side of myeye as I could” to see the effects of deforming the retina. He included a scarydrawing of this experiment. These activities, combined with all the poisonouschemicals (like Hg) that he inhaled during his chemistry experiments, make itsurprising that he lived in such good health to such an old age (84) for that era.

Additive Color MixingRefers to combining colors of lightred + blue = magentared + green = yellowblue + green = cyanred + blue + green = whiteDemonstrate!

The human eye is sensitive to“red”, “green”, and “blue”

The human eye is sensitive to“red”, “green”, and “blue”

The human eye is sensitive to“red”, “green”, and “blue”Most mammals only have two color receptors, but some birds, fish, reptiles,and amphibians have four or five, and thus better color vision. The mantisshrimp has as many as 12 color receptors!

Subtractive Color MixingRefers to combining pigments/colorants and reflected lightyellow + cyan= greenyellow + magenta = redcyan + magenta = blueyellow + cyan + magenta = black

Our brain combines "red", "blue", and "green" colors to make allthe colors of the rainbow:Red, Orange, Yellow, Green, Blue, Indigo, and Violet (ROY G. BIV).Take a close look at your television screen at home…you’ll noticeonly RGB colored pixels!Can you tell which box reflects Red? Green? Blue?

ChallengeBelow are the same three boxes, as viewed through RGB filters.Which filter was used for each picture?

ChallengePost-it Notes of different colors are posted around the room.Predict how they will appear through various filters.Hand out filters