Dropbox has announced the release of open source Lepton. This image compression format has been released under the Apache license.
Lepton is not just a file format for losslessly compressing JPEGs by an average of 22%. It is also doubles as an image compression tool. Dropbox has been using this tool to compress billions of JPEG images hosted on their infrastructure saving them petabytes of storage space.
What Lepton can Do No One Does it Better
Compressing JPEG files at 5 Megabytes per second, the tool is able to preserve the original file bit-for-bit without any loss of data. It is then able to decode the JPEG compression at a rate of 15 Megabytes per seconds with a minimal footprint of 24 MB.
All this is done using some clever mathematical algorithms working with coefficients that are the result of a reversible transformations. It also leverages kernel-protected, read-only memory for compressed files to guarantee they are immutable during the full verification process.
There is more to the entire process and Dropbox has this insightful blog post that explains Lepton in finer details.