Re: Making heat maps color-blind accessible

The design is almost there. Because the design is monochromatic, a person with color deficient vision can use lightness and darkness as a cue.

Others may have suggestions, but here are mine.

1. Add a label (e.g. "1") in each block with a contrasting color. That is white labels on dark blocks and black labels blocks on light
2. Add a border around the lighter blocks which satisfies contrast guidelines.

IMO, I think these additions would make the data more easily interpretable to all users.

Hope this helps.

Best
Elizabeth

On Aug 19, 2021, at 2:03 PM, Mehrnaz Ahmadi <mahmadij@gmail.com<mailto:mahmadij@gmail.com>> wrote:

Hello,

I review charts for publication at my office and I have started pushing for more accessible ways to be applied. We don't have control over everything, but we should make it as accessible as possible.
One rule to follow is to make the visualizations color-blind friendly. One of the rules is to follow the contrast ratio of 3:1 for adjacent colors.
A user has a heat map and they mentioned that if they add labels and borders, it makes it very cluttered. They don't have control over the color contrast for this kind of chart. What is the alternative to make heat maps accessible? Is a tooltip enough?
Here is a screenshot of the heatmap:

<contrast_ratio1.PNG>

I appreciate any wisdom. Thank you so much for your help.

Best,
Mehrnaz

=-=-=-=-=-=-=-=-=-=-=-=-=
Elizabeth J. Pyatt, Ph.D.
Accessibility IT Consultant
IT Accessibility
Office of the Deputy CIO
accessibility@psu.edu<mailto:accessibility@psu.edu> (General accessibility questions)
ejp10@psu.edu<mailto:ejp10@psu.edu>

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https://accessibility.psu.edu