JPEG 2000 - Improvements Over The 1992 JPEG Standard

Improvements Over The 1992 JPEG Standard

Superior compression performance

At high bit rates, artifacts become nearly imperceptible, JPEG 2000 has a small machine-measured fidelity advantage over JPEG. At lower bit rates (e.g., less than 0.25 bits/pixel for grayscale images), JPEG 2000 has a much more significant advantage over certain modes of JPEG: artifacts are less visible and there is almost no blocking. The compression gains over JPEG are attributed to the use of DWT and a more sophisticated entropy encoding scheme.

Multiple resolution representation

JPEG 2000 decomposes the image into a multiple resolution representation in the course of its compression process. This representation can be put to use for other image presentation purposes beyond compression as such.

Progressive transmission by pixel and resolution accuracy

These features are more commonly known as progressive decoding and signal-to-noise ratio (SNR) scalability. JPEG 2000 provides efficient code-stream organizations which are progressive by pixel accuracy and by image resolution (or by image size). This way, after a smaller part of the whole file has been received, the viewer can see a lower quality version of the final picture. The quality then improves progressively through downloading more data bits from the source. The 1992 JPEG standard also has a progressive transmission feature but it is rarely used.

Choice of lossless or lossy compression

Like the Lossless JPEG standard, the JPEG 2000 standard provides both lossless and lossy compression compression in a single compression architecture. Lossless compression is provided by the use of a reversible integer wavelet transform in JPEG 2000.

Random code-stream access and processing

JPEG 2000 code streams are regions of interest that offer several mechanisms to support spatial random access or region of interest access at varying degrees of granularity. This way it is possible to store different parts of the same picture using different quality.

Error resilience

Like JPEG 1992, JPEG 2000 is robust to bit errors introduced by noisy communication channels, due to the coding of data in relatively small independent blocks.

Flexible file format

The JP2 and JPX file formats allow for handling of color-space information, metadata, and for interactivity in networked applications as developed in the JPEG Part 9 JPIP protocol.

Side channel spatial information

Full support for transparency and alpha planes.