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User quotes:
Bravo! I've added the Vischeck site to my personal, mental, list of top web sites, so far there has been only one other in five years! The photoshop plugin is great! I will take more care in future web site designs, if possible I will supply alternative (but still graphic and dhtml oriented) versions of a site with colour adjustments.
-Simon F.
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Information & Links


Vischeck is based on SCIELAB from the Wandell lab at Stanford university.

The dichromat simulation code is from an algorithm described by Hans Brettel, Francoise Vienot and John Mollon in a paper which appeared in the Journal of the Optical Society of America V14, #10 pp2647. (pubmed; see also: pubmed)

Much of the pre- and post-processing of the images utilizes ImageMagick, a freely available image processing package.

A nice primer on human color vision can be found at Clive Maxfield's site.

Color blindness is described in more detail in various places on the web. Try a search in Google. A recent, well-researched addition with plenty of nice graphical examples can be found at this site. There's an interesting list of frequently asked questions (including a good discussion of whether you can 'cure' color blindness) on Dr. Terrace L. Waggoner's site.

Various other visual disorders are described and simulated at this site from Brian Thomas Wagner and Donald Kline at the University of Calgary.

Graphic design and accessibility

There are many resources on human interface design on the web. One of our favourites is Jacob Nielson's site.

Masataka Okabe and Kei Ito have put together an excellent site on how to make scientific presentations more accessible to people with color deficiencies.

Louis Wakeman has written some informative and useful articles about accessibility, including a nice discussion of the use of fonts in HTML. Nick Clark has put together an excellent resource for general accessibility issues at his CurbCuts site.

Newman logo Chuck Newman has an excellent feature on his site that is complementary to Vischeck. He also has a colorblind survey that you may consider filling out.

An excellent treatment of web site design for colour-impaired users comes from British Telecom's research department.

Compensating for Color Deficits

While there is no known cure for color blindness, there are some tricks that individuals with a color deficit can employ to help distinguish colors. For example, color filters can often be helpful (e.g. SeeKey). Some individuals also report using different illuminants to distinguish colors (e.g., examine a fabric under a store's florescent lighting and then move to a window and examine it under daylight).

Tools like WhatColor might be useful for identifying colors on a computer display.


More general resources for vision include the VisionScience website, 'The Joy of Visual Perception', and WebVision. ColorMatters has a nice site with lots of information on color.


Good, general books on color and vision are hard to find. For an overview of the whole subject we recommend Colour Art and Science (The Darwin College Lectures) edited by Trevor Lamb and Janine Bourriau. This is a very readable collection of essays on color that cover the biology of color and color vision and also touch on some of the more philosophical aspects of human color perception.

Naturally, we also have to recommend Foundations of Vision by Brian A. Wandell. Although this is less accessible to the layperson, it will appeal to those looking for a solid, engineering approach to the study of vision. It includes chapters on color vision and pattern sensitivity which are at the heart of the Vischeck engine.

An excellent introduction to color blindness is Color Blindness by Donald McIntyre. It contains a large amount of useful technical information as well as some enjoyable facts (for example, did you know that people once thought that injecting cobra venom and 'lobster extract' into the eyeball was a good way to cure color blindness?). More information is available on the author's website:

A more technical reference is Diagnosis of Defective Colour Vision by Jennifer Birch, which describes color blindness from a clinical and diagnostic perspective.

Finally, for a fascinating account of a color deficit that affects an entire population, try Oliver Sacks' book The Island of the Colorblind. In it, he describes a journey he made in the mid 1990s to a remote island in Micronesia where a large proportion of the people develop a condition known as 'rod monochromatism' and have no color vision at all. His account of the visit is sympathetic, educational and surprisingly entertaining.

General Optometric Resources

The American Optometric Association (AOA) is an alliance between student, state, and military optometric associations that was founded in 1898. They set professional standards, provide education and conduct research into quality vision care. The AOA website is a useful resource for general questions about eye care.

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