Perception Research

We are currently researching perceptual contrast for assessing legibility and accessibility on graphically rich web pages and computer displays. Below are links to some of the early live experimental pages, evaluating the issue(s) in detail.

All About APCA

APCA Articles, Documentation, & Reviews

This page contains an organized listing of articles, documentation, third party and peer reviews, code repositories, white papers, and more about the Accessible Perceptual Contrast Algorithm. Comments welcome at the GitHub repo!

A Short List of Key APCA Documents

The Myndex APCA Linktree has a short list of the most important understanding documents about perceptual contrast. And if you are new to APCA, the entry level overview is "Why APCA"

APCA Discussion Area

Have a question? We have answers! Please come and join the discussions at the APCA Forum.


ΔγAPCA Algorithm
APCA Contrast Calculator

This is a basic plain-vanilla javascript tool for predicting perceptual contrast using the SAPC (SLuv Advanced Perceptual Contrast) math methods. The APCA version is designed to support emerging accessibility standards. For a deeper dive, please see this catalog of resources. Comments welcome at the GitHub repo!

CVD Simulator
Color Vision Deficiency Simulation

We developed this web app to simulate how someone with Color Vision Deficiency** sees the world. We accurately simulate Protanopia, Deuteranopia, and Tritanopia using the Brettel '99 &'97 models. We also present some experimental models, such as Blue Cone Monochromacy.

**Color Vision Deficiency is sometimes referred to as "color blind,"
though that is not accurate except in some very rare cases.

The Web Perception Experiment

COMING SOON: a public study that you can be involved in! Currently under development, it will evaluate how people perceive content in real world situations. Stay-tuned here as we prepare to launch that project. Presently delayed due to COVID-19.

☼ Perceptual Contrast
Live Demos & Experiments

x-Height DEMO:

The need for a CSS x-height property demonstrator page

Text Zoom DEMO:

The need for proportional (and not percentage) zoom capabilities demonstrator page

Font Color Flip DEMO:

This demo illustrates the issues with a single "flip point" for flip a text color from black or white. See the interactive demonstration page

Luminance Contrast TUTORIAL:

This covers the basics of luminance contrast. Written before the invention of APCA, it covers the classic maths and concepts. Understanding Luminance Contrast