JPEGLS

JPEGLS (often written JPEG-LS) is a standard for lossless and near-lossless compression of continuous-tone images. It was developed as part of the JPEG family and standardized jointly by ISO/IEC and ITU-T to provide a simple, efficient alternative to other lossless methods.

The core of JPEGLS is the LOCO-I (Low Complexity Lossless Compression for Images) algorithm, which combines a simple predictive model with context modeling, run-length detection for smooth areas, and entropy coding using Golomb–Rice codes. Its design emphasizes low computational complexity, low memory usage, and fast execution while delivering compression ratios competitive with more complex schemes.

JPEGLS supports both strictly lossless compression and near-lossless operation, where a user-defined maximum error bound permits slightly higher compression by allowing small controlled deviations. It handles multi-component images (such as RGB) and typically operates on full frames rather than providing progressive transmission.

Common application areas include medical and archival imaging, remote sensing, embedded systems, and any context where fast, resource-efficient, reversible compression is desirable. Adoption is more limited in consumer web contexts compared with JPEG and PNG, but JPEGLS is valued in professional and industrial workflows for its performance and simplicity.

Limitations include lack of features like progressive decoding and broader ecosystem support; however, its standardized specification and low complexity make it a practical choice where lossless or bounded-loss image fidelity is required.