Re: Regarding contrast P'atch fixes"

> On Sep 9, 2021, at 2:37 PM, Bruce Bailey <Bailey@Access-Board.gov> wrote:
> All four of these bullets strike me as providing the sort of detailed information that could work well in the context of best-practices supplemental guidance.
> All four of these bullets also strike me as problematic to phrase as WCAG 2.x style success criteria.  I am delighted that we seem to have a way to move forward!

Hi Bruce,

Yes, I do have notes on how a 2.2 style SC could work these, but again these are “stop gap” measures — "fixing a leaky roof with a tarp." At the time (and still) I considered my priority and time management better directed to the more complete solution(s) around APCA.

I still feel that if there is a WCAG 2.3, that an “alternate to the 1.4 section” is a doable and reasonable approach.

An alternate to 1.4 might look like:

Guideline 1.5 Visually Distinguishable, Advanced Alternate to 1.4
1.5.1 Color Coding, inline links (limitations on hue/chroma for information coding)
1.5.2 Discernible Contrast (APCA for discernibility of other text and informational non-text.)
1.5.3 Readable Contrast (APCA for readability of body text, includes minimum weights and size)
1.5.4 Text resize and reflow (no horizontal scroll, etc)
1.5.5 Inter-variable text scaling (large text no more than 120px, small text up to 92px min)
1.5.6 Preferred text contrast and minimum sizes (optional stronger contrast than 1.5.3)
1.5.7 Text leading, kerning, tracking (letter & line spacing, justification & flow rules)
1.5.8 Text layout – element spacing, padding, margins
1.5.9 Images containing content text (special text design, company logo)
1.5.10 Decorative text and decorative images of text (non-content)
1.5.11 Use of busy bg images/textures under content-text prohibited (textures are no more than Lc 30)
1.5.12 Non-text discernible contrast — static elements (shapes, dividers, disabled fields)
1.5.13 Non-text discernible contrast — focus, hover states (clickable buttons, controls)
1.5.14 Non-text understandable contrast — informational icons or with specific meaning (home, envelope, phone)

Clearly this is intended as mostly a 1:1 alternate replacement for the 1.4.x SCs.
As a further example here’s an alternate version of 1.4.3 SC, but using APCA. )It is displayed here with the font size and values for english/latin alphabet for easy reading here, instead of the explainers on a separate page as they would be in WCAG 2.x. In practice, different languages and alphabet types may have different specs specific to their language.
SC 1.5.3 SAMPLE DRAFT — NOT FOR PRODUCTION

Success Criterion 1.5.3 Readable Contrast
(Level AA)
The visual presentation of readable text, and readable text in images, has an Lc contrast value no less than the following:
BODY TEXT: columns of readable text shall use a font & contrast combination no less than:
SMALL • 14px at no less than 300 weight has contrast of Lc 90 or more.
MEDIUM • 18px at no less than 400 weight has contrast of Lc 75 or more.
CONTENT TEXT: all readable text that is not body text shall use a font & contrast combination no less than:
SMALL • 12px at no less than 300 weight has contrast of Lc 75 or more.
MEDIUM • 18px at no less than 400 weight has contrast of Lc 60 or more.
MEDIUM • 24px at no less than 300 weight has contrast of Lc 60 or more.
LARGE • 36px at no less than 400 weight has contrast of Lc 45 or more.
LARGE • 48px at no less than 300 weight has contrast of Lc 45 or more.
ANCILLARY TEXT: this is non-content text that is not significant to the use or understanding of the content. It is used such as for copyright, form place holders, bylines, etc. While it is not particularly important, it must still must be visible.
SMALL • 10px at no less than 300 weight has contrast of Lc 60 or more.
MEDIUM • 24px at no less than 200 weight has contrast of Lc 45 or more.
BODY TEXT: Body text is defined as more than two lines of text in a block or column format, and intended as content.
BOLD FONTS (weight 700): In general, if the weight is increased from 300 or 400 to 700 for a given font size, the required contrast value can be reduced by Lc15.
INCIDENTAL TEXT: text or non-text that is pure decoration, placeholder text, text not visible to anyone, text that is part of a picture containing other significant visual content, or is a brand logotype, has no contrast requirement, however designers are advised that contrast values lower than Lc30 may be invisible to some users.

FURTHER SIMPLIFIED 1.5.3 :

But if the above sample SC is still too much for 2.x, it could be simplified further, for instance only showing Lc values for 14px and 18px text, and then indicating how much the value can be relaxed at a give font size or content type change.

Success Criterion 1.5.3 Readable Contrast (SAMPLE DRAFT)
(Level AA)
The visual presentation of readable text, and readable text in images, has an Lc contrast value no less than the following:

BODY TEXT: columns of readable text shall use a font & contrast combination no less than:
MINIMUM SIZE • 14px @ 300 weight has contrast of Lc 90 or more.
PREFERRED • 18px @ 400 weight has contrast of Lc 75 or more.
CONTENT TEXT: all readable text that is not body text may have a contrast that is Lc 15 less than body text for a given size and weight. In addition, size no less than:
MINIMUM SIZE • 12px @ 300 weight has contrast of Lc 75 or more.
LARGE • 36px @ 400 weight has contrast of Lc 45 or more.
ANCILLARY TEXT: non-content text may have a contrast that is Lc 15 less than required for content text. In addition, size no less than:
MINIMUM SIZE • 10px @ 300 weight has contrast of Lc 60 or more.
BOLD FONTS (weight 700): In general, if the weight is increased from 300 or 400 to 700 for a given font size, the required contrast value can be reduced by Lc15.
BODY TEXT: Body text is defined as more than two lines of text in a block or column format, and intended as content.
CONTENT TEXT: this is readable text important to the understanding or use of the content, but that is not body text in blocks or columns. This includes headlines, buttons, menu controls, etc.
ANCILLARY TEXT: this is non-content text that is not significant to the use or understanding of the content, and can be  It is used such as for copyright, form place holders, bylines, etc. While it is not particularly important, it must still must be visible.
INCIDENTAL TEXT: text or non-text that is pure decoration, placeholder text, text not visible to anyone, text that is part of a picture containing other significant visual content, or is a brand logotype, has no contrast requirement, however designers are advised that contrast values lower than Lc30 may be invisible to some users.

I think this is “functionally equivalent” to the 2.x 1.4.3, but using perceptually correct math and more robust assignment of minimums based on use cases for readability.



Thank you

Andy



> 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"
>  
> 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 <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.w3.org%2FWAI%2FGL%2Flow-vision-a11y-tf%2Fwiki%2FIdeas_for_scope_and_work_topics_(August_2021)%23Proposed_WCAG_2.3_Alternate_Contrast_SC_.28APCA_lite.29&data=04%7C01%7CBailey%40access-board.gov%7Cda471b362d0a4fd0c13e08d973c9d474%7Cfc6093f5e55e4f93b2cf26d0822201c9%7C0%7C0%7C637668132972197022%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=v83SthgxC1EKkmv4eTuQVmKg4JGWQGV%2FjY31PXWRM6g%3D&reserved=0>
>  
>  
> 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 <https://nam10.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdeveloper.mozilla.org%2Fen-US%2Fdocs%2FWeb%2FAccessibility%2FUnderstanding_Colors_and_Luminance&data=04%7C01%7CBailey%40access-board.gov%7Cda471b362d0a4fd0c13e08d973c9d474%7Cfc6093f5e55e4f93b2cf26d0822201c9%7C0%7C0%7C637668132972206975%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=QC%2FPjnTD93BDVTOV96jMQTUolVpL1bd6jpyx5SCayCQ%3D&reserved=0>
>  
> This is written in terms of a general scope of visual accessibility issues and the relation to web content.
>  
>  
> Thank you!
>  
>  
> Andy