Regressive JPEGs: Progressive Scans, Partial Rendering, and Low-Bitrate Animations
Summary
The article explains how progressive (regressive) JPEGs encode image data in multiple scans, enabling a partially rendered image initially and progressively refined frames. It covers the structure of JPEG scans, chroma subsampling, and practical tricks to deliver a sequence of frames by concatenating images, with browser compatibility and performance considerations. It also includes example commands and notes on limitations and potential for unconventional uses.