H-Online writes the Independent JPEG Group (IJG) at the German Institute for Applied Informatics (InfAI) has rolled out a new JPEG library (libjpeg 9) that promises to output lossless JPEG files that are smaller than the equivalent PNG file of the same image. The only downside is that the new compression method is not backwards compatible with earlier versions of the JPEG library, which means images saved using this method will not render in imaging programs and web browsers that don't support libjpeg 9.
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.