You’ll rarely see a healthy person with blue or green skin, unless you’re looking at them under invisible light.
Scientists from National institute of Standards and Technology examined how skin from the forearms of different people appeared under different wavelengths of light. Under visible light, the skin tone seemed similar, but under a wider spectrum, the skin tones varied from blue, to green and even purple.
Study author Catherine Cooksley, a research scientist at NIST, said the “hyperspectral” imaging could eventually be used to see how the skin around injuries is healing. But for now, her goal is to simply get more information about how healthy skin appears under a large spectrum of light.
“The whole point is to try and figure out: what is normal skin?” she said.