Appendix C

APPENDIX D

Contents

As from the JPEG 2000 Web Page (http://www.jpeg.org/JPEG2000.htm), the initiative pursued by JPEG is "intended to provide a new image coding system using state-of-the-art compression techniques, based on the use of wavelet technology". JPEG 2000 is a new standard, intended to create an image coding system useful for many types of still images with different characteristics, allowing different imaging models within a unified system. It should provide low bit rate operations with rate distortion and subjective image quality performance superior to existing standards without sacrificing performance in other points on the rate distortion spectrum, complementing and not replacing the current JPEG standard. This standard is potentially the most significant advancement in still image compression since the introduction of the GIF format and the JPEG standard over a decade ago, because it promises to keep the advantages of this compression format while adding some impressing enhancements. The new algorithm can compress images up to 200 times without appreciable degradation in quality, with lossy techniques, and more than two or three times with lossless techniques. JPEG 2000 uses the new compression scheme, called wavelet, studied in the previous chapters and appendices, instead of the DCT, which is able to store image data as a stream of information at a number of resolutions, and to eliminate the blocked artefacts typical of the DCT-based compression. In this way it could be possible to download only as much resolution as is needed for an image, useful for Internet-like applications. Some other additional features are also in this standard: for example, the ability to add encrypted copyright information and metadata information, which could survive common image editing operations such as resizing and resampling; and the ability to add channels of additional data, such as colour space information and ICC  profiles, which could be useful within a lot of applications.