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Today's hot take: Peer review is not a replacement for critical thinking.

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Regarding your update: to be clear I asked that the old obsolete testing versions be removed (several PRs) as they were causing problems and confusion. The discussions regarding contrast algorithms there are ongoing and far from over. In the meantime we do have the draft APC-RC: readtech.org/ARC/

The APCA Readability Criterion (ARC) provides a range of recommendations for making visual content on illuminated displays more accessible to all users, especially with visual impairments

The claims of legal risks are overblown. Actual accessibility is where the law is centered. The lawsuits that have been brought have been about actual accessibility and not arbitrary numbers. WCAG 2 contrast has never prevailed in a court of law on merits.

Myndex™ Perception Research

Bridge PCA is rebooted and running at bridgepca.com Bridge PCA uses the APCA contrast engine, but provides a modified output that directly indicates WCAG 2 compliance.

bridgepca.com

Bridge PCA Advanced Perceptual Contrast Algorithim WCAG 2 Compatible APCA Contrast

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Myndex™ Perception Research

Based on renewed interest, we re-booted the BridgePCA tool, which provides an modified WCAG 2 value that transitions from the WCAG 2 value for a white color, and as colors get darker, it transitions to a perceptual uniformity based on APCA math, but converted to a WCAG 2 style output. bridgepca.com

bridgepca.com

Bridge PCA Advanced Perceptual Contrast Algorithim WCAG 2 Compatible APCA Contrast

Myndex @myndex.bsky.social · 05/05/2026

If you read 1.4.11 carefully, you'll see that if you have text on the button, only the text needs to meet the contrast minimums. 1.4.11 may be the most toothless SC in WCAG...

Myndex @myndex.bsky.social · 04/05/2026

Nothing has changed.Everything (all guideline categories) were removed from WCAG 3 in 2023 as the entire draft is being re-written. APCA is a candidate contrast method. And WCAG 3 has never been a released guideline. It has always been preview. Independent draft: readtech.org/ARC/

The APCA Readability Criterion (ARC) provides a range of recommendations for making visual content on illuminated displays more accessible to all users, especially with visual impairments

Myndex @myndex.bsky.social · 12/04/2025

BridgePCA satisfies both.

Frank Elavsky (he/him) ⌁ @frank.computer · 12/02/2025

Reposted by Myndex

One of the most important things about our public education system is at risk of being destroyed. 17 states are suing the federal government to bring down Section 504, which is arguably the single-most important law that paved the course of my entire life. www.frank.computer/blog/2025/02...

frank.computer

Section 504 is under attack

A right that I had as a disabled student in the US is at risk of being destroyed.

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Reposted by Myndex

Andrey Sitnik @en.sitnik.es · 19/03/2025

Martians will be speaking at Figma’s main conference 🤯 So proud of our design team! They’ll be talking about dynamic colors—the result of our work around the OKLCH, APCA, and Apcach ecosystem.

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Myndex @myndex.bsky.social · 08/04/2025

2/2 APCA is also available in the IRT public draft "APCA Readability Criterion". APCA can calculate for dark mode, which WCAG 2 can't (not effectively) & APCA is ideal for creating alternate color schemes. For a forced-fit into WCAG 1.4.3, BridgePCA is WCAG 2 compliant. readtech.org/ARC/#objecti...

The APCA Readability Criterion (ARC) provides a range of recommendations for making visual content on illuminated displays more accessible to all users, especially with visual impairments

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Myndex @myndex.bsky.social · 08/04/2025

"Rumors of demise are greatly exaggerated" 😎 APCA is still undergoing testing as a candidate for WCAG 3. As for removals: literally everything was removed from WCAG 3, because the entire conformance model changed. Also, the version of APCA in the old FPWD draft was obsolete, causing confusion. 1/2

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Reposted by Myndex

Sean Wilson @seanw.org · 05/12/2024

Hello Bluesky! 😄 Just to see how this works, for my first post, here's my side project inclusivecolors.com for creating WCAG accessible color palettes for web/UI design. Feedback very welcome! #accessibility #a11y #wcag #design #graphicdesign #webdev #webdesign #uidesign #css #figma #tailwind #ux

inclusivecolors.com

InclusiveColors - Accessible color palette creator

Try it now to create your own color palettes!

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And as a side note: the public beta is real world testing. That’s its purpose. It might interest you to know that many of the early adopters and beta developers have CVD.

The fact it is perceptually uniform is prima facia, well within the limits of a simplified appearance model. It’s not mysterious. But the next release will have features that add accuracy, and improve accommodation for CVD for wide gamut displays. These are what we are most interested in testing.

The models to describe this though are complicated, and not well suited for the specific task as applied to user needs for readability. APCA is a simple and straight forward application of the current science here.

I know what you are saying, and what I fail to get across is that it’s about the guidelines, which all stem from the decades of user testing in reading trials of Legge, Whittaker, Lovie-Kitchin, Arditi, etc. Next, context sensitivity in human contrast perception is well understood…

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A point here though is AGWG does not “do research”, instead deriving from existing research (or not, as the case may be). The guidelines we created with APCA are derived from existing, authoritative peer reviewed research, key cites listed on the link I gave earlier. Does this answer your Q?

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1.4.3 Minimum Contrast, 1.5 multiplication factor — from which research paper? · w3c wcag · Discussion #3853

WCAG 1.4.3 had no user testing, no peer review, and the claims in “understanding” are unsupported by science. There is no real support for the claim WCAG 1.4.3 helps color vision, nor that 4.5:1 is for 20/40. I dissect this in this discussion at the WCAG repo: github.com/w3c/wcag/dis...

github.com

I was checking 1.4.3 Contrast (Minimum)'s page to gain a better understanding of where the 4.5:1 minimum contrast ratio requirement comes from. It cited the paper Arditi, A. and Faye, E. (2004). Mo...

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AGWG does not fund nor perform research. Research is performed pro bono by outside researchers, such as our team. We did have regular interaction and guidance from a US Access Board 508 director, and PhDs in the field. Regarding your sentiment “hard to believe for a W3C proposal”… got a minute?

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In particular, the protan compensation module, and the dataviz (line width) module. User testing is not free, neither is publishing papers in an open source journal. That brings us to the next issue…

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Next, the math. The math traces to modern color vision models and science, including R-Lab, CIECAM02, CAM16, etc. We do have user testing, and we are working on publishing. But this is a lengthy process. And importantly, we have some advancements that we want to focus testing on.

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…bibliography, in particular we rely heavily on Dr Legge, Dr Lovie-Kitchin, and several others. The size, use case, and other features of the APCA related guidelines rest on the evidence-based conclusions of these noted researchers. Selected bibliography: readtech.org/ARC/tests/vi...

The APCA Readability Criterion (ARC) provide a range of recommendations for making visual content on illuminated displays more accessible to all users, especially with visual impairments

Hi Geoffrey, thank you for the comments. Please let me clarify. First, there is math, and there are guidelines. The important part are the guidelines. APCA Readability guidelines are derived from decades of peer reviewed research on readability, inclusive of vision types. These are listed in the..

Myndex @myndex.bsky.social · 16/03/2025

L* does not model self illuminated displays, and is not actually perceptually uniform. APCA uses Stevens et Alia, and is closer to CIECAM02, a more modern model.

Myndex @myndex.bsky.social · 16/03/2025

While APCA fixes this somewhat naturally for sRGB displays, we are releasing the protan compensator extension which addresses the red/black issue for wide gamut displays too.

Myndex @myndex.bsky.social · 16/03/2025

Red on black is a failure of actual accessibility. WCAG2 does not promote actual accessibility, and is harmful to readability for color insensitive vision.

Christian "Schepp" Schaefer @schepp.dev · 15/03/2025

Reposted by Myndex

Service skeet: @ichimnetz.com + team made a color contrast tester that evaluates against both calculation systems simultaneously: palette-tester.9elements.com BTW, I'm as much of a huge fan of APCA as I'm of OKLAB + OKLCH. All those systems that adhere to human perception make so much more sense! 👏🏻

palette-tester.9elements.com

Accessible Color Palette Tester

Create and test color palettes for WCAG & APCA contrast compliance. Name, reorder, and compare colors with real-time contrast ratings. Save & share via URL.

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...if features addressing color interactions are needed: - red and blue (sensation of chromostereopsis, glare, other visual artifacts), - magenta/bright white, (glare, swimming text) - saturated red/green... In sRGB, basic APCA's good, but HDR may create new problems for these and other colors.

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There are other reasons to avoid saturated red, other than contrast. Poor reading against black in sRGB displays, but wide gamut displays can be worse, even if HDR. Red paired with bright white can be difficult to focus on for some. Flashing red can induce seizures. It is an open question...

The published reviews thus far are third party. We will publish when ready. There've been some delays, such as expanding features (e.g. direct protan compensator). If you look at APC-RC, you'll see the scope is wide, spawning the non-profit IRT to manage the project. readtech.org/ARC/#visual-...

The APCA Readability Criterion (ARC) provides a range of recommendations for making visual content on illuminated displays more accessible to all users, especially with visual impairments

Hi Kevin, Mr Roselli misspoke. APCA is still undergoing active development and testing, and is contrast candidate for WCAG 3. All guidelines were removed in 2022/23. Plus the 2021 FPWD version was obsolete, causing confusion. See also IRT's public draft: readtech.org/ARC/#visual-...

The APCA Readability Criterion (ARC) provides a range of recommendations for making visual content on illuminated displays more accessible to all users, especially with visual impairments

What’s Red & Black & Also Not Read?

Red against black is bad news. WCAG 2 passes it (incorrectly), ACPA does not. And soon, the direct protan compensator will be added to APCA, which will help prevent inaccessible red against black on wide gamut displays. See also: tangledweb.xyz/whats-red-bl...

tangledweb.xyz

WCAG 2 Contrast Guidelines claim to help color vision problems, but studies indicate they may do more harm than good in some cases.

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D) Because we are testing. We have an active public beta program, and testing has been ongoing since 2021, and continues. E) And there has been journal published peer review by independent third parties as well. Please mind the rumor mill! 😊 Thank you for reading

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Hi Geoffrey, with all due respect, that is not true nor accurate. A) ALL early guidelines were removed in 2022, because the entire conformance model of WCAG3 changed. B) APCA is candidate, and still undergoing development and testing. C) I am curious where you heard these rumors about testing??

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Years, and lots of testers... and we have a more advanced version with direct protan compensation to release as the next public beta this year. Plus, the draft APC Readability Criterion: readtech.org/ARC/#visual-...

The APCA Readability Criterion (ARC) provides a range of recommendations for making visual content on illuminated displays more accessible to all users, especially with visual impairments

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Reposted by Myndex

bjango.com @bjango.com · 19/11/2024

Say hello to Pinwheel, an amazing way to convert colors and create design systems. bjango.com/mac/pinwheel/

A screenshot of Pinwheel, a new Mac app by Bjango. The screenshot shows a Pinwheel document, full of bright gradients and the user interface to generate the gradients.

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Nils Binder @ichimnetz.com · 17/02/2025

Yes, the L in LCH (aka L*) is close enough to the WCAG 2 lightness curve that 50% with black or white is 4.5:1 Unfortunately, L* is not perceptually uniform on displays or devices. L* puts the "mid point" about #777 The perceptual midpoint is about #999 to #aaa, depending.

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Reposted by Myndex

I built a little tool to check color contrast across an entire palette. 🎨 • Supports both WCAG 2.0 and APCA   • See how all colors compare at a glance • Import/Export CSS or JSON variables  • Make sure your palette works for everyone Try it: palette-tester.9elements.com

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Reposted by Myndex

bjango.com @bjango.com · 19/11/2024

Pinwheel does WCAG and APCA contrast testing, and so much more.

A screenshot of Pinwheel's APCA test results. It show 16 tests passed and 2 tests failed.

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APCA is still in testing and development, and a candidate for WCAG 3. I will mention, now that IP defensive publication has taken place, that the next iteration will have direct protan compensation which is needed for wide gamut displays and more. APC-RC active draft: readtech.org/ARC/#visual-...

The APCA Readability Criterion (ARC) provides a range of recommendations for making visual content on illuminated displays more accessible to all users, especially with visual impairments

It was temporary, in part because the version that was "in" was obsolete, and in mid 2022, WCAG 3 was completely restructuring. APCA is again progressing forward. Also, APCA is part of the APCA Readability Criterion: readtech.org/ARC/#visual-...

The APCA Readability Criterion (ARC) provides a range of recommendations for making visual content on illuminated displays more accessible to all users, especially with visual impairments

It was temporary, in part because the version that was "in" was obsolete, and in mid 2022, WCAG 3 was completely restructuring. Per the AGWG call a couple weeks ago, it is again progressing forward. Also, APCA is part of the APCA Readability Criterion: readtech.org/ARC/#visual-...

The APCA Readability Criterion (ARC) provides a range of recommendations for making visual content on illuminated displays more accessible to all users, especially with visual impairments

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There may be some confusion, as there is also the draft APC Readability Criterion. APCA is still under consideration for WCAG 3. APCA exceeds WCAG 2.x for dark mode. If you need "by the numbers", for light mode try BPCA, or adding Lc 15. readtech.org/ARC/#visual-...