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January 30, 2019

painting of flowers done by Jeff Hanson, who is blind

Color Is Not Inconsequential

As a species, if a person has sight, a majority of the work done by our brains is dedicated to processing visual cues. You may be interested in a blog by "ImageThink", in which they attest that, if our eyes are open, our vision accounts for a majority of brain activity

Beyond that, we are so sensitive to color, and so hardwired to use it, that even artists who are blind or are going blind continue to try to use color even after their ability to see it is gone. To illustrate this point, take a look at the painting to the left. This is a painting done by Jeff Hanson, who suffered vision loss in 2005 due to an optic nerve tumor. See more artwork by blind artists on the web page, 10 Remarkable Painings By Blind and Visually Impaired Artists.

It's not just humans who respond to color; many animals can see certain colors in certain wavelegths, atlhough they may not see the same wavelengths that humans can see. It is believed, for example, that some flowers have patterns with colors in the ultraviolet range, invisible to humans, but visible to bees, so that the flowers attract the bees in order to get pollinated.

People Are So Driven To Color They Try To See It After They Go Blind

Listen to the experiment in which the blind artist tries to see color with sound:

Download the Initial Transcript as a docx file.

Summary: Michael Curran, of NV Access Limited, developed AudioScreen, an experiment in which hte attempted to allow blind people to "see" images via audio using a touch screen for Windows 8+ compatible devices. By running a finger over the touch screen, sound reflects the nature of the image. In this audio demonstration, he uses it to explore a map of Australia, a rainbow, the earth from space, a cartoon house, and a sun set.

Audio Source: as accessed 5 February 2019

Employability. Pride. Mindset. All affected by color.

Color is not just a "nice" thing to have -- we as a species are hardwired to use it, so fiercely, that even the blind try to use color. Extrapolate that, and it's easy to understand why we should use color in our documents. Color seduces us to look harder. Color is absolutely fundamental to us as a species, and that extends to those who are color blind. There's an effort, often for emotional reasons, for color-blind people to try to "tag" colors they can't see so that they may fit in.

The ability to see color affects employability. It affects personal pride. It affects your mindset. It matters in safety. Color is most definitely not inconsequential.

“It doesn’t affect my job, but it does make being an artist difficult,” he said. “I feel like everyone else has an advantage over me because they can make their work look more realistic and create gradients that I have such a hard time putting together. People never notice, but I always feel like I can do better.”

Dec. 15, 2015 | Air Force Tech. Sgt. Juan Hernandez

A map of ocean currents for colorblind users.Wikipage File:Ocean currents 1943 for colorblind users.png

Livelihoods Depend On It

For about three out of four of them, he said, the results come as a total shock. ''Their whole livelihood depends on passing the test,'' he said.

When Colorblindness Cramps CareersBy TANYA MOHNMAY 23, 2001 |New York Times Archives

People Depend on Technology

"I am a 16 years old male with a diagnosis of retinitis pigmentosa. I study at the Loaiza Cordero Institute for visually disable persons and I need to know how can I install in my computer a program in which the background is black and the letters are white and how can I change the size of the letters (magnificized). Thanks for your help."

January 26, 2009 | WebAim Blog

To the right is medical imaging showing the difference betweenn a normal eye and one with Pigmentosas.

Normal vs Pigmentosas

Medical imaging of a normal eye and one with pigmentosas. The rods in the normal eye are straight, but in the diseased eye are collapsed and scattered

This Is Important. Because of Technology, Online Color Is Not Consistent.

Below there is an example of the exact same web page displayed against three different browsers. Although instructions were provided to the web page using the same directives, the browswers rendered the colors differently.

Screenshot comparing display in different browsers

Three browswers, (Chrome, IE, and Firefox, respectively) each displaying the exact same web page, differently, on a Windows machine.

Screenshot comparing display in different browsers but in grayscale

Three browswers, (Chrome, IE, and Firefox, respectively) each displaying the exact same web page, differently, on a Windows machine -- but in grayscale.

Accessibility Standards Exist in Context

For text, a color can pass or fail depending upon the size of the text. WebAim's Color Contrast Checker provides an easy way to check.

This Is Important. Contrast Against Background Is Not Enough For Text

This is where the Web Aim's Link Checker comes in. It is not only testing contrast against the background, it is testing against the surrounding text

Let's test some example colors! All of these are great colors, but let's see how to use them!

  • #d0012b
  • #fbc804 -- as an accent color

The red color seems to pass. But notice the caveat in the explanation (as accessed 29 January 2019):

For optimal usability and accessibility, links should be underlined. If links are not underlined by default, they may be reliant on color and may fail WCAG 2 Level A. To address this color reliance, you must have a 3:1 contrast ratio between link text color and the surrounding body text color. Additionally, the link must present some other non-color indicator (typically it will become underlined) on mouse hover and keyboard focus. Both the link color and the body text color must have a 4.5:1 contrast ratio (or 3:1 for large text) with the background to meet WCAG 2 Level AA.

Take note that the screenshot below has a red border, in fact, the same color red as is being checked in the color-contrast checker. It's not a large border, it is only five pixels wide. This is not something a blind person with a screen reader deals with. But it is something a person with low vision or color-blindness deals with. Pay attention to what the presences of the red border does in terms of your attention.

screenshot of color contrast for link checker showing that although technically it passes, underlining is recommended

Wait.... Are You Sure Your Students Can Even GET the Text?

This is a reminder that even the very definition of "accessibility" needs consideration. Is the student able to access the font you've chosen for your online document? Take, for example, the fact that the accessibility of a color can depend not only the color itself and its contrast against the background, but the size of a form, or its shape can also affect accessibility.

As of January 2019, Arial is natively available on Windows: 99.84% Mac: 98.74%, but Calibri is available on Windows: 83.41% but on Macs: 38.74% according to the website, CSS Font stack

screenshote showing that not all fonts are available equally on all workstations.  Arial is available on most computer workstations, but Calibri is not

Success Criteria for Low Vision Are More Obscure Than For Screen Readers

Text is linear (or should be). Visual representation is not. Nor are its elements discreet.

So,Any Recommendations?

In general, if you have good contrast between your elements, and lots of "white space" in between them, that in itself goes a long, long way to making material truly accessible. Quantifying success is quite hard. Many accessibility checkers rightfully tell you that contrast must be checked manually. A good start is to look at the guidelines provided by the U.S. Department of Health and Human Services to guide us, particularly, its page for determining the accessibility of documents.

Checklist From The Department of Health And Human Services

See Section B: All Office Documents Containint Color as accessed 19 December 2018



Traceability back to 508



Does any information conveyed with color have a non-color method for understanding?

WCAG 2.0 Success Criterion 1.4.1 exit disclaimer icon



Does all text (with the exception of logos) have a contrast ratio of 4.5:1 or greater no matter the font   size?

WCAG 2.0 Success Criterion 1.4.3 exit disclaimer icon

(Size stipulation not considered by HHS)


And Remember That In So Many Ways, Technology Empowers

Read about Be My Eyes. According to the website (as accessed 29 January 2019) it works by a system of sighted volunteers offering to help those who are blind or who have low vision. Blind or low-vision person requests assistance, and in turn, connect with a sighted person.


Among many companies,Adobe desersve special treatment as a resource for color assessment. It has a long, strong history of exploring color, and how it is used and displayed via technology.

See also the page Adobe for resources we use here at our institution.

  • Sighted volunteers work to assist Blind and Low Vision People through Be My Eyes
Paciello Group
  • Website for downloading the Paciello Group's Color Contrast Analyzer for Windows or Mac (as accessed 29 January 2019.
  • The hexidecimal color codes from the passing colors can be copied and used in Word or Blackboard Learn’s content editor. More Background Information on how the Paciello Group's Color Contrast Analyzer works is available at Pressbooks online article, Creating Accessible Word Documents – Color Contrast for Accessibility (as accessed 29 January 2019)
  • Coblis Color Blindness Simulator

    This tool enables you to simulate multiple types of colorblindness, such as: Trichromatic view, Anomalous Trichromacy,Dichromatic view,Monochromatic view

    as Accessed 4 January 2019

  • Colorblind Web Page Filter

    Accessed 29 November 2018

Apple OS X
Microsoft Office Support
DRAFT Accessibility Requirements for People with Low Vision