ARC • APCA Readability Criterion — a set of web-standard guidelines for text and non-text for use with the APCA contrast algorithm. Latest published version at this link:

𝜟𝜱✴︎ or Delta Phi Star is a variant method of determining lightness contrast, and a sibling of APCA and SACAM. It is a simplified version using easily invertible standardized maths, however it lacks some useful properties such as polarity sensitivity. In fact, it is intended for applications where a "general" simplifed perceptual contrast is des…