Re: minimal contrast and technique G174

Hi Gundula,

Your email would make an excellent GitHub issue, could you post it there?

Alastair

Sent from my phone, apologies for typos.
________________________________
From: Niemann, Gundula <gundula.niemann@sap.com>
Sent: Tuesday, June 23, 2020 2:33:31 PM
To: Alastair Campbell <acampbell@nomensa.com>
Cc: WCAG <w3c-wai-gl@w3.org>
Subject: minimal contrast and technique G174


Hello Alastair,



when looking over the color contrast relevant Success Criteria and their understanding pages I came over some techniques for the minimum contrast which I would like to discuss.

For easier reference, let me repeat the link here.

https://www.w3.org/WAI/WCAG21/Understanding/contrast-minimum.html



In technique G174 it says (again I give the direct link for your convenience):

https://www.w3.org/WAI/WCAG21/Techniques/general/G174

"When the contrast between the text and its background for some portion of the page has not been designed to meet the contrast level for Success Criterion 1.4.3 or 1.4.6, it is possible to meet these guidelines using the "Alternate Version" clause in the conformance requirements (Conformance Requirement 1). […]"



In the sequel of the text, a high contrast theme is explicitly mentioned as the only alternative.



As a consequence, a provider of software with a web based User Interface can reach compliance by providing a very shady and soft colored theme not fulfilling any color contrast consideration and a high contrast theme (in most cases high contrast white on black) as alternative.

I feel this does not really meet user's needs. A high contrast theme is very harsh and painful for most eyes with good color vision. A shady theme is not well perceptable for most users in bright environments or with glare on the screen.

In addition we observed users going away from high contrast white-on-black when they find a dark theme (dark background with brighter text fulfilling minimum contrast but not high contrast).

This matches well the elaboration done and research cited on https://uxmovement.com/content/why-you-should-never-use-pure-black-for-text-or-backgrounds/ .



So what is the rationale behind that recommendation in G174?

Shouldn't it be changed to oblige authors and software providers to offer a default theme that fulfills minimum contrast (level AA) and in addition a high contrast theme fulfilling the AAA success Criterion?

Or to offer at least a minimum contrast theme plus a high contrast theme as alternatives complying to 1.4.3 and 1.4.6, respectively, if the default theme does not comply?

I suggest to change G174 to request a minimum contrast theme as alternative if 1.4.3 is not fulfilled and a high contrast theme as alternative if 1.4.6 is not fulfilled.



Best regards,

Gundula



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Dr. Gundula Niemann

SAP Accessibility Competence Center

SAP SE