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JPEG 2000 Part 1, Core Coding, Lossy Compression

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name ISO/IEC 15444-1:2004. Information technology -- JPEG 2000 image coding system -- Part 1: Core coding system [using lossy compression] (formal name); JPEG 2000 core coding, lossy compression (common name)
Description Compression encoding generally used for full color and grayscale continuous-tone pictorial images; additional general information on the coding process is provided in J2K_C. Lossy encoding employs irreversible transforms described in the Notes below.
Production phase May be applied in initial-state picture creation; often used for middle- and final-state archiving or end-user delivery.
Relationship to other formats
    Subtype of J2K_C, JPEG 2000 Part 1, Core Coding System
    Used by JP2_J2K_C_LSY, JP2 File Format with JPEG 2000 Core Coding, Lossy
    Used by MJP2_FF_LSY, Motion JPEG 2000 File with Lossy Compression

Local use Explanation of format description terms

LC experience or existing holdings See JP2_FF.
LC preference See JP2_FF.

Sustainability factors Explanation of format description terms

Disclosure Open standard. Developed by Joint Technical Committee ISOAEC JTC 1, Information technology, Subcommittee SC 29, Coding of audio, picture, multimedia and hypermedia information in collaboration with ITU-T.

ISO/IEC 15444-1:2004. Information technology -- JPEG 2000 image coding system -- Part 1: Core coding system.

See complete list of ISO/IEC JPEG 2000 documents in JP2_FF format specifications.

Adoption See JP2_FF
    Licensing and patents See J2K_C
Transparency See J2K_C
Self-documentation See JP2_FF
External dependencies None.
Technical protection considerations See JP2_FF

Quality and functionality factors Explanation of format description terms

Still Image
Normal rendering Good support.
Clarity (high image resolution) See J2K_C
Color maintenance See J2K_C
Support for vector graphics, including graphic effects and typography See JP2_FF
Functionality beyond normal rendering See J2K_C and JP2_FF

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension Not applicable.  See JP2_FF
Internet Media Type Not applicable.  See JP2_FF
Magic numbers Not applicable.  See JP2_FF
File type brand (ISO Base Media File Format) Not applicable.  See JP2_FF

Notes Explanation of format description terms


Robert Buckley, for many years a research fellow in the Xerox Innovation Group, and chair of the committee that developed the JPEG2000/Part 6 standard, offers the following insights: "The multiple component transforms in Annex G of Part 1 refer to the 'component decorrelating transforms' and describe the reversible and irreversible versions of the component or 'color' transform. The wavelet transform is applied independently to each component that results from the 'color' transform, and these may also be reversible and irreversible. The reversible transforms are necessary but not sufficient for lossless. You must also remember to not quantize the transformed coefficients; in other words, just pass them through." (Private communication, December 15, 2004)

From "Wavelet Transforms in the JPEG-2000 Standard": The JPEG-2000 codec is transform-based. It employs multicomponent transforms, wavelet transforms, and bit-plane coding techniques, in order to provide a framework for both lossy and lossless compression. Both reversible integer-to-integer and nonreversible real-to-real transforms are employed, the latter being referred to as "irreversible" in the terminology of the standard. . . . The input to the encoding process is an image consisting of one or more components. Before any further processing takes place, each component has its sample values adjusted by an additive bias, in a process called DC level shifting. The bias is chosen such that the resulting sample values have a nominal dynamic range (approximately) centered about zero. Then, a multicomponent transform (MCT) may be applied collectively to a number of the components. Next, a wavelet transform (WT) may be applied to each component individually. Finally, the resulting transform coefficients are quantized and then encoded. In the case of lossless coding, reversible transforms must be employed and all quantizer step sizes are forced to be one. In the lossy case, either reversible or nonreversible transforms can be used, but the two types of transforms cannot be intermixed.

David S. Taubman and Michael Marcellin's book JPEG 2000: Image Compression Fundamentals, Standards and Practices (Boston: Kluwer Academic Publishers, 2002) notes that the color transform is optional and "may be used only when three or more color components are available . . . . the transform converts the RGB data into . . . a luminance (or intensity) channel and two color difference channels." Color transforms may themselves be reversible (RCT, with integer approximation to YUV color space) or irreversible (ICT, with floating point YUV). The discrete wavelet transforms (DWTs), which are not optional, may also be reversible (using the "integer 5-3 filter" specified in the standard) or irreversible (using the "floating point 9-7 filter").


Format specifications Explanation of format description terms

Useful references


Last Updated: 06/17/2021