RE: Regarding contrast P'atch fixes"

Hi Andy, thank you for sharing these suggestions. I have provided some questions and personal thoughts below regarding the items:

  *   Minimum background brightness for dark text on a light background, requiring the background be no darker than #a0a0a0 (Addresses the 2.x dark pairs failure).
[Jonathan] I’m not clear exactly what you are stating here – If you are talking about #a0a0a0 (gray) on white #FFF– that would be 2.6:1 contrast.  If you are talking about #a0a0a0 on #000 that would be 8:1 contrast using the current algorithm.   While I agree full white on a black background can be problematic – 8:1 contrast isn’t enough for some users with low vision.   What other values could be considered and can you please clarify which colors are for which background/foreground with your suggestion.

  *   Minimum padding around text of 1em, *if* the text container’s background (div) is more than 2:1 contrast with the larger surrounding background. (addresses local adaptation issues)
[Jonathan] This seems like it would come up often with buttons.  Adding 1em would significantly increase the size of all buttons potentially spreading out controls too much impacting people with limited field of vision.  It would be good to get some mockups created to show and discuss how we might find something that achieves the goal and is practical to implement.

  *   Minimum contrast for body text as above at 7:1 (11:1 preferred).  Body text defined as more than two lines of related text in a block or column.
[Jonathan] This would be very useful.  I personally find this issue beyond body text though and I would like to discuss extending this to links and interactive elements as well.

  *   No fonts lighter than 300 weight for body text, and no smaller than 14px for body text (16px recommended) (addresses important spatial frequency limitations on perception).
[Jonathan]  Personally I find 300 weight fonts too thin and would recommend 400 weight for body or really any text as that is the default regular weight for fonts anyway.

Jonathan

From: Andrew Somers <andy@generaltitles.com>
Sent: Thursday, September 9, 2021 3:41 PM
To: public-low-vision-a11y-tf@w3.org; Jonathan Avila <jon.avila@levelaccess.com>; Shawn Henry <shawn@w3.org>; Bruce Bailey <Bailey@Access-Board.gov>; Christopher Loiselle <chris.loiselle@oracle.com>; Sam Waller <sdw32@cam.ac.uk>
Subject: Regarding contrast P'atch fixes"

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In reference to Sam’s query regarding adding SCs to WCAG 2.x contrast to improve it, In the fall of 2019, I had been working on some “patch” SCs for WCAG 2.2 to create stepping stones to the contrast metric for Silver, but I was not able to get them researched and fully formed to submit by the deadline, as I was too busy preparing the larger work for Silver.

To quickly sum up some of what I had been proposing/working on for contrast for 2.2, that got stuck on the back burner.


  *   Minimum background brightness for dark text on a light background, requiring the background be no darker than #a0a0a0 (Addresses the 2.x dark pairs failure).


  *   Minimum padding around text of 1em, *if* the text container’s background (div) is more than 2:1 contrast with the larger surrounding background. (addresses local adaptation issues)


  *   Minimum contrast for body text as above at 7:1 (11:1 preferred).  Body text defined as more than two lines of related text in a block or column.


  *   No fonts lighter than 300 weight for body text, and no smaller than 14px for body text (16px recommended) (addresses important spatial frequency limitations on perception).

These do not address the issues with reverse polarity of light text on dark, though that problem is solved with APCA, which also includes corrections for the above, which is why we have been discussing an “alternate” SC as outlined on the Wiki here:

https://www.w3.org/WAI/GL/low-vision-a11y-tf/wiki/Ideas_for_scope_and_work_topics_(August_2021)#Proposed_WCAG_2.3_Alternate_Contrast_SC_.28APCA_lite.29


Supplemental Guidance

Is this on GitHub where I can fork it so I can work on it? The first thing I’d like to address is the ambiguous nature of a number of entries. There is a number of uses of terms like “many” or “most” with no real quantification or supporting references. I think starting there, the rest of the document will start to fall into place.

ALSO,

If you are interested, this is a link to the “Introduction to Color for Accessibility” that I wrote for the Mozilla site in their accessibility section. It’s in a slightly different format, but covers a lot of what I’d think should be in the “Supplemental Guidance”.

https://developer.mozilla.org/en-US/docs/Web/Accessibility/Understanding_Colors_and_Luminance


This is written in terms of a general scope of visual accessibility issues and the relation to web content.


Thank you!


Andy