This site is a live web page of the primary GitHub repo for the APCA/SAPC project. Documentation linked below.


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APCA GitHub Repo


APCA is the Accessible Perceptual Contrast Algorithm, a new way to predict contrast for text and non-text for content on self illuminated displays.

Questions? Ask in our Discussions Forum

This is also where we discuss draft guidelines and proposals. Please post all comments or discussions here and not in the satellite repositories so they can be tracked and resolved.


Simple Overview, QuickStart, and FAQ

These are intended for end users, and those interested in a plain language overview without a lot of the math & theory.

Sciency Stuff!

Maths! Vision Science! Photons on Parade!

Poster: a picture of crash test dummies crashing out of a car, and text that says don't be a dummy! Stop using low contrast text. At the bottom it says APCA the world is reading       Smokey the bear saying  ONLY YOU CAN STOP LOW CONTRAST      Uncle Sam saying I want you to use high contrast text

The main catalog of related articles, peer reviews, repositories, white papers, and more!

APCA Linktree

Smaller, selected link collection.

Myndex Research on Twitter

Local Repo Documentation

The APCA-W3 GitHub Repo

Over there is the W3 licensed version, and it’s the same as the published npm package.

The Bridge-PCA GitHub Repo

The BridgePCA is backwards compatible with WCAG 2, and it’s the same as the published npm package.

The ColorParsley GitHub Repo

ColorParsley is a micro library for auto parsing color strings of all kinds, also on npm.

APCA Contrast Calculator

The canonical demo tool at Myndex

Bridge PCA Contrast Calculator

Try out the Bridge PCA tool at Myndex

Myndex CVD Simulator

Color insensitive vision simulation (aka colorblind). Includes deuteranopia, protanopia, tritanopia, and blue cone monochromacy/achromatopsia.

Myndex Perception Research

Demos and Experiments relating to the project.

APCA The Revolution Will Be Readable