Spatial frequency Packages

APCA: the Accessible Perceptual Contrast Algorithm, a modern contrast method that improves readability contrast on self-illuminated displays. Developed for the W3C's WCAG 3 and other standards.

Delta Phi Star is a general purpose method of determining perceptual lightness contrast developed by Andrew Somers (Myndex Research), and is a sibling of APCA and SACAM. It is a simplified method using easily invertible standardized maths, however it lack