Accurate Contrast<br>Using the APC<span class="flipH">A</span>

<p align="left" class="por " style="margin: -36px 24px 12px"><br> &emsp13;<img src="https://badgen.net/badge/INF&thinsp;/&#10148;/cc0066?labelColor=990033" alt="INFO" />&nbsp;<a href="https://git.myndex.com"><img src="https://badgen.net/badge/APCA/Resources/3300aa" alt="APCA Resources" /></a>&nbsp;<a href="https://readtech.org/ARC/"><img src="https://badgen.net/badge/APCA Readability/Criterion/ba12aa" alt="APCA Readability Criterion" /></a>&nbsp;<a href="https://github.com/Myndex/SAPC-APCA"><img src="https://badgen.net/badge/APCA/Main Repo/e86800" alt="APCA/Main Repo" /></a><br> &emsp13;<img src="https://badgen.net/badge/STT/&#10148;/aa6600?labelColor=884400" alt="STATS" />&nbsp;<a href="https://npmjs.org/package/apca-w3"><img src="https://badgen.net/npm/v/apca-w3?color=884400&icon=npm" alt="version" /></a>&nbsp;<a href="https://npmjs.org/package/apca-w3"><img src="https://badgen.net/npm/dt/apca-w3?color=995500&icon=npm" alt="downloads" /></a>&nbsp;&thinsp;<a href="https://github.com/Myndex/SAPC-APCA"><img src="https://badgen.net/github/stars/Myndex/SAPC-APCA/?color=0055ff" alt="stars" /></a>&emsp13;<a href="https://github.com/Myndex/apca-w3/src/"><img src="https://badgen.net/badge/JS/Vanilla/778d66" alt="plain vanilla JS" /></a><br> &emsp13;<img src="https://badgen.net/badge/APP/&#10148;/007700?labelColor=005500" alt="APPS" />&nbsp;<a href="https://apcacontrast.com"><img src="https://badgen.net/badge/APCA/Live Demo/e06000" alt="APCA Live Demo" /></a>&nbsp;<a href="https://bridgepca.com"><img src="https://badgen.net/badge/BridgePCA/Live Demo/0055bb" alt="BPCA Live Demo" /></a>&nbsp;<a href="https://www.myndex.com/CVD/"><img src="https://badgen.net/badge/Color Blind/Simulator/bb0055" alt="CVD Simulator" /></a><br> &emsp13;<img src="https://badgen.net/badge/SCL/&#10148;/0000aa?labelColor=000088" alt="Social" />&nbsp;<a href="https://twitter.com/MyndexResearch"><img src="https://badgen.net/badge/@/OnTwitter?color=0066cc&icon=twitter" alt="twitter" /></a>&emsp13;<a href="https://techhub.social/@Myndex"><img src="https://badgen.net/badge/@/OnMastodon?color=6600cc&icon=mastodon" alt="mastodon" /></a>&emsp13;<a href="https://www.linkedin.com/in/andrew-m-somers/"><img src="https://badgen.net/badge/in&nbsp;@/LinkedIn?color=0066cc" alt="linkedin" /></a>&emsp13;<a href="https://bsky.app/profile/myndex.bsky.social"><img src="https://badgen.net/badge/•&nbsp;@/Bsky?color=2244ff" alt="bluesky" /></a><br> </p>

QuickStart:

• Easy Intro to APCA? This is the simple, plain-language introduction to APCA that you've been looking for. This is an ideal place to start and is an easier version of WhyAPCA.

• linktr.ee/Myndex In an effort to pare down the mountain of material, this linktree is composed of the essential links, with the most basic at the top.

The Accessible Perceptual Contrast Algorithm

• Basic Tool & Quickstart Docs The basic APCA demonstration tool with live font examples and general design guidance for designers and developers.
• APCA Readability Criterion In depth guidelines for accomodating user needs regarding visual content, includes testing methods, conformance models, best practices, and more. Public Working Draft.

Independent Peer Reviews of APCA and<br>Third Party Comparisons vs WCAG 2

Why did APCA become popular? Because it follows actual science, including the science of readability with visual impairments. APCA promotes actual accessibility. Yet there have been unfounded rumors that it has not been peer reviewed or tested, when there is a growing corpus of third party reviews, including journal published, as can be seen at APCA Reviewed.

General Overview

• Why APCA? This brief introduction into APCA describes how it solves the problems of WCAG_2 contrast. See Easy Intro to APCA? for the plain language version.
• APCA in a Nutshell Basic overview for using APCA, including simple use-case based conformance levels. This is a bare bones version, for the deeper dive see APCA Readability Criterion
• APCA FAQ APCA Frequenty Asked Questions (in development)
• Easy Intro to APCA? This is the simple plain-language introduction to APCA that you've been looking for. This is a simpler version of WhyAPCA above.

APCA Technical Documentation

• APCA W3 Functions/API Using the API of the APCA W3 package.
• Links To Tools & Apps Some of the tools,apps, and design systems that have adopted APCA.
• Main Readme Doc (HTML version) Includes the math and walkthroughs, and additional resources.
• Documentation Index An index of APCA related documentation relating to code libraries.
• The Main List This page, i.e. you are HERE.

Social Media and Forums

• APCA Forum Discuss, ask questions, fend off lions...
• Tangled Web Andrew's Tangled Web Tech Blog
• Social Medieval
  • Myndex on Twitter
  • Myndex on Mastodon
  • Andrew on LinkedIn
  • Inclusive Reading Technologies on Twitter
  • Inclusive Reading Technologies on Mastodon

Sciencey Stuff!

Maths! Theory! Vision Science! Photons on Parade!

• The Realities And Myths Of Contrast And Color A plain language, in-depth primer to vision, color, and contrast for design, with an emphasis on typography and readability needs. Published in Smashing Magazine.
• The base APCA-W3 formula in LaTeX math for your viewing and calculating pleasure.
• Regarding Exponents Some notes and explaination regarding the powercurve exponents.
• Standard Observer Model Draft standardized environment.

<!-- - [Visual Contrast Draft Whitepaper](https://www.w3.org/WAI/GL/task-forces/silver/wiki/Visual_Contrast_of_Text_Subgroup/Whitepaper) (Work in progress) -->

For Developers

• Repo List List of APCA and related respositories.
• Important Change Notices Current constants refer to 0.0.98G-4g
• List Your Tool Here! Have you created a tool using APCA or BridgePCA? Let us know!
  • Third Party Tools Letting us know gets your tool onto the official third party tool listing.
• APCA™ Integration Compliance Discusses levels of implementation.
• How to Contribute Contributions welcome — in particular we need to redesign the apcacontrast.com tool for responsiveness, set up rollup for builds, and a few other things. Help wanted!

Related Repositories

• APCA Documentation Repository The docs repo and forum for APCA and SACAM
• APCA W3 Repository The W3 version code repo for web content
• Max Contrast A very simple, APCA compatible text color flipper. Flips from black to white text at middle contrast.
• Inclusive Reading Technologies The repo for IRC and the APCA Readability Criterion.
• Bridge PCA Repository Bridge PCA - the WCAG 2 compatible version
• DeltaPhiStar Repository A simplified general purpose contrast algorithm using L*
• Color Parsley Repository Fast and easy color string parsing — a NodeJS dependency for many of the SAPC libraries.
• SeeStars Repository A microlibrary for calculating L*
• Missing Intro Repository A correction and rebuttle to a flawed analysis
• FancyFontFlipping Repository At what point should text flip from black to white? This repo houses experiments and discussion of "font flipping". See also Max Contrast, above.
• Tiny Trim This is a CSS sheet of terse classes, useful for quick adjustments without having to add a style="" great for site development when you have a client watching and breathing down your back, LOL.

<!-- - [**Color Styles**](https://github.com/Myndex/colorstyles) colorstyles is a CSS color stylesheet with a terse but easy to use methodology for color classes — in development, some of this