MozJPEG reduces file sizes of JPEG images while retaining quality and compatibility with the vast majority of the world's deployed decoders.
MozJPEG is based on libjpeg-turbo. Please send pull requests to libjpeg-turbo if the changes aren't specific to newly-added MozJPEG-only compression code. This project aims to keep differences with libjpeg-turbo minimal, so whenever possible, improvements and bug fixes should go there first.
It's compatible with libjpeg API and ABI, and can be used as a drop-in replacement for libjpeg. MozJPEG makes tradeoffs that are intended to benefit Web use cases and focuses solely on improving encoding, so it's best used as part of a Web encoding workflow.
MozJPEG is meant to be used as a library in graphics programs and image processing tools. We include a demo
cjpeg tool, but it's not intended for serious use. We encourage authors of graphics programs to use MozJPEG's C API instead.
- Progressive encoding with "jpegrescan" optimization. It can be applied to any JPEG file (with
jpegtran) to losslessly reduce file size.
- Trellis quantization. When converting other formats to JPEG it maximizes quality/filesize ratio.
- Comes with new quantization table presets, e.g. tuned for high-resolution displays.
- Fully compatible with all web browsers.
- Can be seamlessly integrated into any program using libjpeg.