Improving JPEG baseline compression

Abstract

The original JPEG (Joint Photographic Experts Group) still image data compression standard (ITU-T T.81 - ISO 10918:1 ) was frozen in the early 90psilas. It had several parts, but most users are only aware of the Baseline mode. This widely used standard was the effort of a joint committee sponsored by ISO/IEC and ITU-T (formerly CCITT). The original committee JPEG committee moved on and created several more joint and non-joint standards. The ITU-T parent was receptive to building enhancements onto the first JPEG standard. The first ITU-only upgrade (T.851) came out in September 2005. It added an additional (fee-free) arithmetic coder, extended the allowed DCT input precision, and created an alternative baseline coder. This talk will review JPEG baseline and show the compression improvements made possible (without a quality change) by using the arithmetic coder in T.851. The original JPEG baseline is lossly convertible into and out of this new standard.