ITU-T.81 – ISO/IEC 10918-1 is one of the dominant image compression standards. If that name doesn’t mean anything to you – it is just ordinary JPEG. The JPEG committee – of which I’m a member of – released various new standards in the past view years that provided better performing compression schemes, more flexible image representations and smarter file formats. While some of them were adopted in the industry, as JPEG-LS (aka LOCO) and JPEG 2000 in the digitial movie and medical industry, all the rest of the world still speaks old traditional JPEG.
It is probably time to update the standard, and some members of the JPEG committee are looking into bringing 10918-1 up to date. New features might include lossless compression, high-bitrate compression and support for alpha channels. However, much care must be taken in extending a standard as predominant as JPEG, and one of the highest priorities in any such attempt should be backwards compatibility to existing implementations.
What can be done? At first, it takes a “verification model” that implements the proposed extensions. And here it is:
available for public, under the GPL licence for everyone to try. This is a subversion repository. Use “anonymous” as user name, and “jpeg” as password, and you’re in.
This is a completely new implementation of 10918-1,and unlike most (or all) other codecs you might know, this implementation is complete. It features not only the DCT based process most codecs support, but also the JPEG lossless (yes, there is one) process, the hierarchical mode, arithmetic coding (patents run out by now), DNL markers, 12bits per pixel.
As this is might become a verification model for the proposed extensions, you find of course also new features, as lossless coding with the DCT based process; this codec is able to encode images in a special way such that they can be reconstructed without any loss by using the new codec you find here – and can be viewed with any existing JPEG codec as well – then of course with some minimal loss.
If you want to contribute, you are more than welcome to do so. You can either add to the program (ask me for write access to the repository) or report any bugs you find. For that, sign up at the bug tracker here:
Obviously, the JPEG is also looking for industry to show interest in such applications and extensions, and would be happy to hear from you if this development is interesting for you. If so, please ask me for the official JPEG questionnaire on low-complexity coding, and I will forward to the committee. Or approach the committee yourself via your national delegate. Or contact me:
thor at math dot tu dash berlin dot de
Greetings, and Happy JPEGing,