Libjpeg 9 improves lossless JPEG compression
The Independent JPEG Group (IJG) at the German Institute for Applied Informatics (InfAI) has released a new version of the libjpeg library. The developers say it can compress photos in JPEG format in a lossless way and, apparently, libjpeg 9 outputs lossless JPEG files that are smaller than the equivalent PNG file of the same image.
IJG recommends using
cjpeg -rgb1 -block 1 -arithmetic to create lossless images with the library, but also warns that the new compression will make the resulting images incompatible with older versions of the library. Decoders that use a version of libjpeg prior to version 9 will not be able to render these images.
The Independent JPEG Group is not associated with the Joint Photographic Experts Group of the ISO standards organisation and the ITU (International Telecommunications Union), which developed the official ISO/IEC 10918-1 standard for JPEG and JPEG2000. However, the IJG says that libjpeg is used in programs such as Firefox, IrfanView and Picasa.
Written in C, the library's source code is released under an open source software licence and is available to download free as a zip or TAR.GZ archive. The IJG's download catalogue also lists older versions of the library.