JPEG2000 (ISO 15444) is an image compression schematic put forth by the Joint Picture Experts Group in December 1999 and accepted as a Full International Standard one year later. The purpose was explore and exploit hew theories and advances in compression technology to replace the JFIF standard.
The specifications therein are still under work, though Part 1 of 10 parts of the standard has been released for general review, and Part 2 is expected in mid 2002. But what's all this talk about "parts"? Isn't it just a picture format?
Not quite; JPEG2000 refers to a whole collection of standards put together in a cohesive package which allows an image to be built using those standards. As said, there are 10 parts total to the JPEG2000 core:
- Part 1 - Core coding system
- Part 2 - Extensions (adds more features and sophistication to the core)
- Part 3 - Motion JPEG 2000 (support for image sequences)
- Part 4 - Conformance testing
- Part 5 - Reference software (Java and C implementations of Part 1)
- Part 6 - Compound image file format (for pre-press and fax-like applications)
- Part 8 - JPSEC (security)
- Part 9 - JPIP (interactivity and delivery protocols)
- Part 10 - JP3D (volumetric coding)
Of these parts, only the first, the Core, is required to create basic images, though because this is being coached in part by industry groups the other 9 specs will be important to make the format "wide enough" for commercial uses.
The core spec outlines some very interesting compression concepts, of which the most talk is about wavelet compression. It is supposed to allow compression of 2000% without the loss in quality of most of the Fast Fourier Transformation and Discrete Cosine Transform codecs currently used -- realistic lossless compression was is one of the major goals of JPEG2000.
In the format zone, another interesting addition is the ability to change compression thresholds and even the very routines in the flow of the image, so in the picture of the blonde at the beach, the blonde could be compressed at 200:1 using lossless wavelet while her boyfriend off to the side could be made, uhm, "less sharp" by using a 1000:1 %25 loss wavelet stream.
As for use of JPEG2000, that's a bit trickier; to use the basic design outlined, which translates into basic still images, usage is free and unlimited. However, to use the extensions outlined in the later parts, especially Part 2, royalties will be required (though there is nothing that will stop a certain 3rd party from making their own free extension set).
References: jpeg.org, ISO 15444