Dropbox Lepton
Lepton is a tool and file format for losslessly compressing JPEGs
Lepton image compression, saving 22% losslessly from images at 15MB/s. Lepton achieves a 22% savings reduction for existing JPEG images, by predicting coefficients in JPEG blocks and feeding those predictions as context into an arithmetic coder. Lepton preserves the original file bit-for-bit perfectly. It compresses JPEG files at a rate of 5 megabytes per second and decodes them back to the original bits at 15 megabytes per second, securely, deterministically, and in under 24 megabytes...