From Andrew Somers, a great primer on how color vision works and how illuminated display technology maps perception to luminance contrast, color gamut, etc. Especially useful is his writeup of not only WCAG 2’s limitations for determining proper contrast for meeting accessibility needs but also the upcoming standards like APAC (Accessible Perceptual Contrast Algorithm) that will pave the way for more useful and relevant a11y standards.
Notes about perception
From Moby Dick, chapter 42, “The Whiteness of the Whale”:
Is it that by its indefiniteness it shadows forth the heartless voids and immensities of the universe, and thus stabs us from behind with the thought of annihilation, when beholding the white depths of the milky way? Or is it, that as in essence whiteness is not so much a color as the visible absence of color, and at the same time the concrete of all colors; is it for these reasons that there is such a dumb blankness, full of meaning, in a wide landscape of snows – a colorless, all-color of atheism from which we shrink? And when we consider that other theory of the natural philosophers, that all other earthly hues – every stately or lovely emblazoning – the sweet tinges of sunset skies and woods; yea, and the gilded velvets of butterflies, and the butterfly cheeks of young girls; all these are but subtile deceits, not actually inherent in substances, but only laid on from without; so that all deified Nature absolutely paints like the harlot, whose allurements cover nothing but the charnel-house within; and when we proceed further, and consider that the mystical cosmetic which produces every one of her hues, the great principle of light, for ever remains white or colorless in itself, and if operating without medium upon matter, would touch all objects, even tulips and roses, with its own blank tinge – pondering all this, the palsied universe lies before us a leper; and like wilful travellers in Lapland, who refuse to wear colored and coloring glasses upon their eyes, so the wretched infidel gazes himself blind at the monumental white shroud that wraps all the prospect around him. And of all these things the Albino Whale was the symbol. Wonder ye then at the fiery hunt?
Research continues on whether humans (and other animals) have the ability to perceive magnetic fields:
Many birds have a compass in their eyes. Their retinas are loaded with a protein called cryptochrome, which is sensitive to the Earth’s magnetic fields. It’s possible that the birds can literally see these fields, overlaid on top of their normal vision. This remarkable sense allows them to keep their bearings when no other landmarks are visible.
But cryptochrome isn’t unique to birds – it’s an ancient protein with versions in all branches of life. In most cases, these proteins control daily rhythms. Humans, for example, have two cryptochromes – CRY1 and CRY2 – which help to control our body clocks. But Lauren Foley from the University of Massachusetts Medical School has found that CRY2 can double as a magnetic sensor.
Vision is amazing, even more so when you take into account the myriad other things that animals and insects can detect beyond just our “visible” EMF spectrum. See also: box jellyfish with their surprisingly complex (and human-like) set of 24 eyes.
Another excellent short episode of Radiolab, featuring a conversation with two people I wouldn’t expect to hear on stage together:
Oliver Sacks, the famous neuroscientist and author, can’t recognize faces. Neither can Chuck Close, the great artist known for his enormous paintings of … that’s right, faces.
Oliver and Chuck–both born with the condition known as Face Blindness–have spent their lives decoding who is saying hello to them. You can sit down with either man, talk to him for an hour, and if he sees you again just fifteen minutes later, he will have no idea who you are. (Unless you have a very squeaky voice or happen to be wearing the same odd purple hat.)
If you’re interested in the science of face perception, I stumbled across this relevant paper this week: Cortical Specialization for Face Perception in Humans (pdf) co-authored by Tel Aviv University’s Galit Yovel.
A paper in Nature Photonics describing the waveplate mechanism found in the eye of mantis shrimp (stomatopods). These amazing critters can see hyperspectral color ranging from the infrared to the ultraviolet, can perceive different planes of circular polarized light, and have eyes that operate and dart about (saccade) independently. This paper is basically demonstrating that man-made material science has a lot to learn if we want to catch up with nature’s technology.
Personal side question: what are these shrimp on the lookout for that’s led to such a sophisticated eye??