The technology behind preview photos
Aug 6, 2015Edward Kandrot

Summary
Introduced a technology to deliver low-resolution image previews within 200 bytes by embedding a compressed JPEG payload with a custom header. This involved creating a fixed JPEG header (version, width, height) and a Huffman table optimized for the target byte count, allowing clients to reconstruct a blurred image preview. This reduced profile and page load times by 30% on slow connections and ensured immediate preview display on all connections.