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What is JPEG2000 ?
JPEG2000 is the second version of the popular image compression method and file format called JPEG, written by the ISO group Joint Photographic Experts Group, ISO/IEC 29 WG01. It differs from the classic .jpg: JPEG2000 is an integrated system for coding digital images, while JPEG DCT is only a compression method for still images. JP2 presents a cleaner and more intelligent compression method which is based on an mathematical algorithm called wavelets.
What are Wavelets ?
A wavelet is a mathematical function useful in digital signal processing and image compression. The use of wavelets for these purposes is a recent development, although the theory is not new. The principles are similar to those of Fourier analysis, which was first developed in the early part of the 19th century.
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JPEG2000 uses wavelets to compress the image, while JPEG used DCT functions. By using wavelets the image signal is decomposed into different little waves, that when summed up together became as equal to the original as possible. The wavelet decomposition can be reversible (100% reconstruction) or unreversible (no total reconstruction). In images, this means lossless or lossy compression.
Is JPEG2000 lossless or lossy ?
Both. JP2 has two different kinds of wavelets for compression, family 5x3 (reversible) and 9x7 (irreversible). When compressing an image youll have both choices: loosing quality but having little files or preserve all the quality but still saving a lot of space.
What about Metadata and the File Format ?
The JP2 File Format is fully XML based. It is based in DIG35, a image industry standard (Digital Imaging Group).
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