This is a port of the C++ Lepton JPEG compression tool that was released by DropBox dropbox/lepton. We developed a port of the library to Rust, which has basically the same performance characteristics with the advantage of all the safety features that Rust has to offer, due to the work involved in performing an exhaustive security check on the C++ code and the fact that DropBox has deprecated the codebase.

With precise bit-by-bit recovery of the original JPEG, the Lepton compression library is designed for lossless compression of baseline and progressive JPEGs up to 22%. JPEG storage in a cloud storage system is the main application case. Even metadata headers and invalid content are kept in good condition.

Some operations of this library are vectorized such as the IDCT using the Wide crate, so you can get a significant boost if you enable +AVX2.

• Rust 1.65 or Above

git clone https://github.com/microsoft/lepton_jpeg_rust cd lepton_jpeg_rust cargo build cargo test cargo build --release

There is an lepton_jpeg_util.exe wrapper that is built as part of the project. It can be used to compress/decompress and also to verify the test end-to-end on a given JPEG. If the input file has a .jpg extension, it will encode. If the input file has a .lep extension, it will decode back to the original.jpg.

It supports the following options:

lepton_jpeg_util.exe [options] <inputfile> [<outputfile>]

There are many ways in which you can participate in this project, for example:

• Submit bugs and feature requests, and help us verify as they are checked in
• Review source code changes or submit your own features as pull requests.
• The library uses only stable features, so if you want to take advantage of SIMD features such as AVX2, use the Wide crate (see the idct.rs as an example) rather than intrinsics.

This project has adopted the Microsoft Open Source Code of Conduct. For more information see the Code of Conduct FAQ or contact [email protected] with any additional questions or comments.

Copyright (c) Microsoft Corporation. All rights reserved.

Licensed under the Apache 2.0 license.