SAPC-APCA
apca-w3
| SAPC-APCA | apca-w3 | |
|---|---|---|
| 11 | 1 | |
| 402 | 140 | |
| - | - | |
| 7.3 | 5.1 | |
| 1 day ago | 8 months ago | |
| CSS | JavaScript | |
| GNU General Public License v3.0 or later | GNU General Public License v3.0 or later |
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SAPC-APCA
- Why the New Contrast Method APCA
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How Americans of different ages spend their time on weekdays [OC]
Why the New Contrast Method APCA
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Change the colour of grey text back to black on website using poor contrast text
For a more future oriented version (as setting a font to black wont work with dark pages), check out the CSS Color Module Level 5 spec for color-contrast(), which will automatically choose a color that has a proper contrast ratio: https://www.w3.org/TR/css-color-5/#funcdef-color-contrast
One caveat is it's currently only supported in Safari technical preview.
Another thing worth mentioning is the relative brightness algo used in the repo for the linked plugin is using the WCAG 2 formula for relative luminance. This works pretty well in light mode for non-colored backgrounds, but doesn't incorporate perceived luminosity differences of different hues very well. A better algorithm to use here is the Advanced Perceptual Contrast Algorithm (APCA), which is the one used in the WCAG 3 working spec. It more accurately accounts for hue: https://github.com/Myndex/SAPC-APCA
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Please Stop Using Grey Text
Note the licensing note in the repository[1] of the APCA™ index the author’s company[2] promotes:
> The files currently in this repository are presently considered pre-release, and as such do not have a permanent license attached. In this repositiory, all files present are under a time-barred beta license, and intended for use with web-based content only, and not for any other use without written permission.
The non-pre-release stuff[3] offered to W3C is better but still seems to be intended to end up non-FOSS:
> Files in this repository are licensed to the W3/AGWG under their cooperative agreement for use with WCAG accessibility guidelines for web-based content only, and not for any other use.
(The question being, of course, how much of this is copyrightable at all.)
[1] https://github.com/Myndex/SAPC-APCA/
[2] https://www.myndex.com/CVD/
[3] https://github.com/Myndex/apca-w3/
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WCAG 3 and updated contrast checkers?
Second: There are a number of contrast checkers that use APCA technology. The canonical "official" one is https://www.myndex.com/APCA/ but I want to mention it is an open public beta, and is not backwards compatible with WCAG_2 (this is in part because WCAG_2 is not perceptually accurate and thus the areas where WCAG_2 incorrectly fails pairs that APCA will pass is at issue).
- WCAG 3 will use a new color contrast method called APCA
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I made a tool to check the contrast between two colours using the new contrast algorithm being drafted for WCAG 3 — also includes fun rgb/hsl/lch sliders and buttons to adjust either colour to a desired contrast!
Andrew Somers W3 AGWG Invited Expert Color Science Researcher Myndex Perception Research Inventor APCA/co-author WCAG3
apca-w3
-
Please Stop Using Grey Text
Note the licensing note in the repository[1] of the APCA™ index the author’s company[2] promotes:
> The files currently in this repository are presently considered pre-release, and as such do not have a permanent license attached. In this repositiory, all files present are under a time-barred beta license, and intended for use with web-based content only, and not for any other use without written permission.
The non-pre-release stuff[3] offered to W3C is better but still seems to be intended to end up non-FOSS:
> Files in this repository are licensed to the W3/AGWG under their cooperative agreement for use with WCAG accessibility guidelines for web-based content only, and not for any other use.
(The question being, of course, how much of this is copyrightable at all.)
[1] https://github.com/Myndex/SAPC-APCA/
[2] https://www.myndex.com/CVD/
[3] https://github.com/Myndex/apca-w3/
What are some alternatives?
a11y-color-tokens - Generate accessible UI colors from your base color tokens.
csscolorparser - Go (Golang) CSS color parser library
web-skills - A visual overview of useful skills to learn as a web developer
rainbow - Rainbow — Accessibility Contrast Tool for Text on Images
CCAe - The Colour Contrast Analyser (CCA) helps you determine the legibility of text and the contrast of visual elements, such as graphical controls and visual indicators.
a11y-contrast - A CLI utility to calculate/verify accessible magic numbers for a color palette.
validate-access - Parse a & Validate a given directory with multiple entries
csscolorparser-rs - Rust CSS color parser library
luminosity-css - 💡 Duo of customizable CSS classes to define a light source location and cast dynamic shadows off elements based on their relative position. Themable and customizable with CSS variables
gifa11y - Gifa11y is a customizable vanilla javascript plugin that easily adds accessible play/pause buttons to animated GIFs.
feedback - Public feedback discussions for: GitHub for Mobile, GitHub Discussions, GitHub Codespaces, GitHub Sponsors, GitHub Issues and more! [Moved to: https://github.com/github-community/community]
csstree - A tool set for CSS including fast detailed parser, walker, generator and lexer based on W3C specs and browser implementations