3 Colour Vision
Two misconceptions, (1) that hues are physical properties residing in wavelengths of light, or (2) that hues are our perceptions of individual wavelengths of light, can each lead to the further misconception that hues inherently form the linear sequence that we see in the spectrum, and that we only arbitrarily bend this linear sequence into a circle. In fact, the hue of a light is our perception of an overall direction of imbalance in the spectral composition of the light relative to daylight, and these directions of imbalance have a 360-degree range, towards long, middle, short or long and short wavelengths. The spectral hues are are the ways in which we perceive a very strong imbalance towards a single wavelength, and thus comprise only part of that circuit; the non-spectral hues magenta and purple are the ways in which we perceive an imbalance towards long and short wavelengths. Hue circle adapted after DeValois and Webster (2011), Scholarpedia, 6(4):3073
Anatomical and Physiological Aspects
Foundations of vision (Brian Wandell)
Complete textbook, free to read online
Eye, brain and vision (David Hubel)
https://web.archive.org/web/20070606010129/http://hubel.med.harvard.edu/bcontex.htm
Complete textbook, free to read online or download via Internet Archive Wayback Machine.
A vision of the brain (Semir Zeki, 1993)
The joy of visual perception (Peter Kaiser):
Online book on vision including colour vision; you can even ask the author questions (but read the book first!).
Webvision: The organization of the retina and the visual system (University of Utah).
Comprehensive medical website on vision science.
Handprint (Bruce MacEvoy)
https://www.handprint.com/HP/WCL/color1.html#designeye (design of the eye}
https://www.handprint.com/HP/WCL/color2.html (the geometry of color perception)
Color vision (De Valois and Webster)
Colour and colour vision: Background information (Colour and Vision Research Laboratories).
The bases of colour vision (Brian Wagner and Douglas Kline)
A brief organized list (Brian Wandell)
Physclips (UNSW)
Some Demonstrations Useful for Studying Perception (Greg C Elvers)
How do our colour-blind cones achieve colour vision, and how does this explain the existence of three primaries? (Deleniv, S. 2015).
Hyperphysics (C.R. Nave, Georgia University):
http://hyperphysics.phy-astr.gsu.edu/hbase/ligcon.html (Light and Vision)
http://hyperphysics.phy-astr.gsu.edu/hbase/vision/colviscon.html (Colour Vision)
Short pages on various topics related to colour, light and vison, set out in web arrangement
Color vision (Craig Blackwell)
https://www.youtube.com/watch?v=V73k_0KuUJo (Color Vision 4: Cones to See Color)
https://www.youtube.com/watch?v=VeDOpGRMZ7Y (Color Vision 5: Color Opponent Process)
https://www.youtube.com/watch?v=gH84_XipdNs (Color Vision 6: Color with 1, 2 or 3 Cones. In Humans and Various Animals}
https://www.youtube.com/watch?v=orwuGY5VQXQ (Color Vision 7: Primate Color Vision)
https://www.youtube.com/watch?v=8DGYsYU5yqQ (Color Vision 8: Opsins and the Evolution of Color Vision)
https://www.youtube.com/watch?v=ruKMIgmsUbw (Color Vision 9: Melanopsin in the Eye)
Seeing color through different eyes - Individual differences in human color perception (Michael Webster)
Boynton, Robert M., Human color vision (1979)*
*Available to "borrow" for 14 days and read online but not download.
A splash of colour (University of Oxford)
Four short films on how we see colour .
Eyeball anatomy (AnatomyZone)
Why we're blind to the color blue (Caleb Kruse)
The Optical Design of the Human Eye: a Critical Review (Rafael Navarro)
How the eye functions (1941)
Online color challenge (Xrite)
Isihara colour vision test
Vischeck
"Vischeck is a way of showing you what things look like to someone who is color blind. You can try Vischeck online- either run Vischeck on your own image files or run Vischeck on a web page. You can also download programs to let you run it on your own computer".
No such thing as color - What it's like to be color blind (Laura Evans)
Island of the colorblind (Oliver Sachs)
Ishihara and other colour vision tests (The College of Optometrists)
Color Blindness – learn all about it (Colblindor)
Includes various articles plus online CVD tests and tools.
Tests for colour blindness (Ishihara)
Myndex™ sRGB Color Vision Deficiency Simulator (Andrew Somers)
The youtube theory of colour vision (David Briggs)
http://hueangles.blogspot.com/2018/08/the-youtube-theory-of-colour-vision.html
"When writing for a general audience, vision scientists often refer to the long-, middle- and short-wavelength cone classes (L, M and S) as red, green and blue cones respectively. While this simplification may seem harmless it unfortunately has been the starting point for a cascade of misunderstandings about human colour vision. To begin with it reinforces the assumption that hues are properties residing in wavelengths of light, and then understandably leads to the assumption that the three cone types individually detect red, green and blue hues/wavelengths. Together these assumptions lead to the conclusion commonly encountered in discussions of colour vision on social media that we “only really see three colours”. In turn this conclusion has teamed up with the homunculus fallacy to spawn a model of colour vision in which the cone cells send hue signals directly to an observing brain. When the brain receives a combination of cone signals that could be produced by a “real” colour in the spectrum it “thinks it sees” that colour. This model bears little resemblance to current science but has achieved the status of orthodoxy on several online platforms." Unfortunately the model has infected some otherwise quite reliable resources, including Pixar in a Box's Color Science (Dominic Glynn) and several videos by Technology Connections (Alec Watson).
https://www.youtube.com/watch?v=R3unPcJDbCc (Michael Stevens [Vsauce], This Is Not Yellow, September 2012)
https://www.youtube.com/watch?v=l8_fZPHasdo (Colm Kelleher, How we see color, January 2013)
https://www.youtube.com/watch?v=iPPYGJjKVco (Steve Mould, Colour Mixing: The Mystery of Magenta, The Royal Institution of Great Britain, February 2013)
https://www.youtube.com/watch?v=uNOKWoDtbSk (Dianna Cowern, Does This Look White to You?, October 2015)
Perceptual Aspects
Handprint (Bruce MacEvoy)
https://www.handprint.com/HP/WCL/color4a.html (basic forms of color)
https://www.handprint.com/HP/WCL/color4.html (adaptation, anchoring & contrast)
Visual perception (Daniel Chandler):
Various topics on visual perception (not colour)
Colorful notions (BBC, 1985)
Presents the controversial but stimulating ideas of Edwin Land who personally explains and demonstrates his experiments.
What art can tell us about the brain (Margaret Livingstone)
Colour constancy illusions and painting (David Briggs, 2018)
Striking illusions published by neuroscientists Dale Purves and Beau Lotto show something rather different to what Purves and Lotto claimed they show. The video examines these and other colour constancy illusions, what they do and don’t tell us about visual perception and how they illustrate a basic practical difficulty involved in painting appearances.
87 optical illusions & visual phenomena (Michael Bach).
Akiyoshi's illusion pages (Akiyoshi Kitaoka)
Brightness illusion catalogue
Illusions and demos (Edward Adelson):
Adelson, E., 2000. Lightness perception and lightness Iilusion.
http://web.mit.edu/persci/gaz/gaz-teaching/index.html (Lightness Perception and Lightness Illusions (interactive movies in Flash based on the Adelson paper)
The illusions index (University of Glasgow, Centre for the Study of Perceptual Experience)
A dress rehearsal for vision science (Journal of Vision)
Special issue of the Journal of Vision on "The Dress" illusion of 2015.
The future of perceptual illusions : From phenomenology to neuroscience.
Optical illusions (eChalk)
http://www.echalk.co.uk/amusements/OpticalIllusions/colourPerception/colourPerception.html
Interactive version of some Purves and Lotto illusions.
Some more illusion sites:
The Illusion Contest channel
Psykinematix Widget Collection
It's not easy seeing green and Himba color perception (Mark Liberman)
An experiment on color perception among the Himba tribe of Namibia depicted in the 2011 BBC program "Do You See What I See?" appears to show Himba subjects who are unable to distinguish apparently very differently coloured stimuli that fall within the same colour category in their language but are readily able to distinguish apparently very similarly coloured stimuli that for them fall into different colour categories. The story has been repeated ever since in places like the New York Times and RadioLab. Curious to know why the experiment had never been published, linguistics Professor Mark Liberman in 2015 contacted the scientists mentioned in the episode and established that the film did not show an actual experiment but instead showed a performance "concocted for illustrative purposes" by the authors of the documentary and that the apparent experimental results acted out in the performance were not proposed or endorsed by the scientists involved. In actual experiments of the type shown, the targets used are normally one Munsell hue step apart (and thus neither wildly different nor indistinguishable), and the differences recorded are in the speed of recognition of the odd target, measured in microseconds.
Interactive Programs
Chapter 6. Color perception (Sage)
Good range of interactive demonstrations of colour vision, from the companion website to the textbook Sensation & Perception by Bennett L. Schwartz and John H. Krantz (2015).
Software for visual psychophysics: an overview (Hans Strasburger)
Huedoku (Gabriel Mott)
https://angel.co/projects/157480-huedoku-a-fun-game-that-expands-your-mind
See also "Same Same or Different" and "Color is Relative" on same page.
Project LITE - Atlas of visual phenomena:
http://lite.bu.edu/ (Online or download - Windows/Mac)
Dozens of demonstrations of optical illusions and visual phenomena. NOTE: The demonstrations of additive and subtractive mixing used in the course are from this site:
Color uncovered (Exploratorium)
App for Ipad and Android
Same, same or different (Gabriel Mott)
Interactive version of a classic Albers contrast demonstration.
Color is relative (Gabriel Mott)
Assimilation grid illusion generator
Grayscale illusion
Metamers, single cell response and Triple cell response (Brown University)
http://www.cs.brown.edu/exploratories/freeSoftware/catalogs/color_theory.html (Online/Windows/Mac)
Part of a series of applets demonstrating various aspects of spectral stimuli and the human visual response that were extremely useful but unfortunately seem to be very difficult to get working on modern computers. Also unfortunately in this category is Pehr Sallstrom's lovely DOS program Spektral.