JPEG 2000. A wavelet-based digital picture compression format

When it comes to image compression, the first standard that springs to mind is JPEG. Created in 1991, this standard is still one of the most widely used in photographic image compression. It is still very effective when used at low to medium compression ratios, but the poor quality of images obtained at higher compression ratios, as well as its lack of flexibility and functionality, testify to its inability to satisfy all the requirements of today's applications, particularly professional ones. With this in mind, the JPEG 2000 image compression format was developed in 2000.

This dossier comprises two inseparable articles.

This first article [TE 5 320] presents :

• a brief history ;

• the objectives of its development ;

• basic concepts of the DWT (Discrete Wavelet Transform) ;

• main features ;

• the functions and techniques used in the JPEG 2000 coding chain.

And in the second article [TE 5 322] :

• the JPEG 2000 family of standards ;

• Container formats used to encapsulate, store or transport images encoded in JPEG 2000 ;

• performance in relation to JPEG and other codecs for still and moving images;

• applications in the fields of digital imaging, digital cinema and video, particularly in the areas of archiving and distribution.

The section devoted to wavelets takes a "physical-practical" rather than a mathematical approach, to help us understand both the wealth of functionalities induced, with in particular intrinsic scalability in image quality and/or resolution, and the performance achieved in comparison with other image codecs using the DCT (Discrete Cosine Transform).

Many terms and the text of some figures have been kept in English (in italics in the text), to facilitate the reading and use of technical documents. Numerous references, including lists of norms, standards and recommendations as well as organizations, are provided in the "For further information" document.

A list of abbreviations and acronyms can be found at the end of this article (§