Myndex
@myndex.bsky.social
Research: 🧪 vision color contrast readability accessibility
Develop: APCA, SACAM
Orgs: IRT Founder,W3C Invited Expert
Write: IRT Readability Criterion, WCAG3 Co-Author
IRT: readtech.org
APCA: apcacontrast.com
ColorSim: myndex.com/CVD/
Blog: TangledWeb.xyz
Develop: APCA, SACAM
Orgs: IRT Founder,W3C Invited Expert
Write: IRT Readability Criterion, WCAG3 Co-Author
IRT: readtech.org
APCA: apcacontrast.com
ColorSim: myndex.com/CVD/
Blog: TangledWeb.xyz
BridgePCA satisfies both.
April 12, 2025 at 9:33 AM
BridgePCA satisfies both.
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...
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...
APCA Readability Criterion • Contrast
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
readtech.org
April 8, 2025 at 10:44 AM
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...
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...
"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
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
April 8, 2025 at 10:44 AM
"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
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
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.
It might interest you to know that many of the early adopters and beta developers have CVD.
March 17, 2025 at 11:36 PM
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.
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.
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.
March 17, 2025 at 11:34 PM
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.
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.
APCA is a simple and straight forward application of the current science here.
March 17, 2025 at 11:34 PM
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.
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…
Next, context sensitivity in human contrast perception is well understood…
March 17, 2025 at 11:34 PM
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…
Next, context sensitivity in human contrast perception is well understood…
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?
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?
March 17, 2025 at 8:27 PM
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?
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?
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...
I dissect this in this discussion at the WCAG repo:
github.com/w3c/wcag/dis...
1.4.3 Minimum Contrast, 1.5 multiplication factor — from which research paper? · w3c wcag · Discussion #3853
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...
github.com
March 17, 2025 at 8:27 PM
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...
I dissect this in this discussion at the WCAG repo:
github.com/w3c/wcag/dis...
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?
Regarding your sentiment “hard to believe for a W3C proposal”… got a minute?
March 17, 2025 at 8:27 PM
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?
Regarding your sentiment “hard to believe for a W3C proposal”… got a minute?
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…
User testing is not free, neither is publishing papers in an open source journal.
That brings us to the next issue…
March 17, 2025 at 8:27 PM
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…
User testing is not free, neither is publishing papers in an open source journal.
That brings us to the next issue…
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.
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.
March 17, 2025 at 8:27 PM
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.
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.
…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 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...
APCA Readability Criterion • Contrast
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
readtech.org
March 17, 2025 at 8:27 PM
…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 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...
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..
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..
March 17, 2025 at 8:27 PM
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..
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..
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.
APCA uses Stevens et Alia, and is closer to CIECAM02, a more modern model.
March 16, 2025 at 1:07 AM
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.
APCA uses Stevens et Alia, and is closer to CIECAM02, a more modern model.
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.
March 16, 2025 at 1:04 AM
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.
Red on black is a failure of actual accessibility. WCAG2 does not promote actual accessibility, and is harmful to readability for color insensitive vision.
March 16, 2025 at 1:04 AM
Red on black is a failure of actual accessibility. WCAG2 does not promote actual accessibility, and is harmful to readability for color insensitive vision.
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! 👏🏻
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! 👏🏻
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.
palette-tester.9elements.com
March 15, 2025 at 7:43 AM
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! 👏🏻
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! 👏🏻
...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.
- 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.
March 15, 2025 at 9:29 AM
...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.
- 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.
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...
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...
March 15, 2025 at 9:29 AM
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...
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-...
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-...
APCA Readability Criterion • Contrast
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
readtech.org
March 15, 2025 at 9:11 AM
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-...
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-...