ISO/IEC 15444-17:2023

Overview - ISO/IEC 15444-17:2023 (JPEG 2000 Part 17)

ISO/IEC 15444-17:2023 extends the JPEG 2000 image coding system to support efficient, scalable coding of images that contain strong spatial discontinuities (so-called “discontinuous media”). It defines two new breakpoint component types - QuadBPT and TriBPT - collectively called breakpoint components, and specifies the codestream syntax, decoding and reconstruction procedures needed to recover breakpoint data and to apply breakpoint-dependent spatial wavelet transforms.

This Part 17 text is common with ITU‑T T.816 and complements the base JPEG 2000 Parts (ISO/IEC 15444-1 and -2) by enabling discontinuity-aware transforms and hierarchical, refinable representations of breakpoint locations.

Key topics and technical requirements

• Breakpoint components (QuadBPT / TriBPT): New image component types that encode locations and values of discontinuities in a hierarchical, successively refinable way.
• Breakpoint-dependent spatial wavelet transforms: Wavelet-like transforms whose basis functions can be discontinuous at specified breakpoints and can replace the standard transforms in ISO/IEC 15444-1 for selected components or tile-components.
• Codestream extensions: New marker segments and syntax to identify breakpoint components, associate components with breakpoint-dependent transforms, and carry hierarchical breakpoint data.
• Decoding & reconstruction procedures: Detailed procedures for embedded bit‑plane decoding of breakpoints, code-block handling (CL and LL bands), MQ coder contexts, significance and refinement passes, and spatial induction/extrapolation methods for reconstructing sample values.
• Scalability & hierarchical description: Breakpoint data are encoded to support progressive transmission and multi-resolution decoding.
• Interoperability & conformance: Rules for codestream conformance and decoder behavior when breakpoint-dependent features are present.

Applications - who benefits and why

• Depth maps and 3D imaging: Native example use-case - depth maps naturally contain sharp discontinuities where breakpoint-aware transforms improve compression quality.
• Computer graphics, compositing and layered imagery: Efficient coding of images with occlusion boundaries or alpha edges.
• Remote sensing and aerial imagery: Scenes with abrupt terrain or target boundaries where discontinuities are common.
• Any JPEG 2000 implementer: Codec developers, imaging software vendors, hardware encoder/decoder designers, and standards integrators who need to handle discontinuous media with scalable, high-quality compression.

Related standards

• ISO/IEC 15444-1 (JPEG 2000 Part 1 - core coding system / ITU‑T T.800)
• ISO/IEC 15444-2 (Part 2 - extensions)
• ITU‑T T.816 (V1) - common text for this Recommendation

Keywords: ISO/IEC 15444-17:2023, JPEG 2000, QuadBPT, TriBPT, breakpoint components, breakpoint-dependent wavelet transforms, discontinuous media, depth maps, codestream extensions.