File extension

.jp2

JPEG 2000 Part 1 (JP2)

.jp2 files are JPEG 2000 images: a wavelet-based image format (ISO/IEC 15444) used in digital cinema, medical imaging, and archives; related extensions include .j2k, .j2c, .jpf, and .jpx.

Known meanings

Formats and reference material for .jp2

JPEG 2000 Part 1 (JP2)

Wavelet-based image compression system and the JP2 file format, ISO/IEC 15444-1

  • 2d-graphics
  • Joint Photographic Experts Group (ISO/IEC / ITU-T T.800)
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Details

Format notes

JPEG 2000

JPEG 2000 is an image compression standard from the JPEG committee, published as ISO/IEC 15444 and ITU-T T.800. Instead of the 8x8 block DCT used by JPEG, it applies a discrete wavelet transform and codes the result with embedded block coding, which gives it features JPEG lacks: lossless and lossy compression in one codestream, resolution and quality scalability, region-of-interest decoding, high bit depths, and no visible blocking artifacts at high compression.

File Formats

The .jp2 format, defined in Part 1, wraps a codestream in a box-based file structure. A JP2 file begins with the signature box 00 00 00 0C 6A 50 20 20 0D 0A 87 0A followed by an ftyp box, a header box with image properties and color specification, and a jp2c box holding the codestream. A raw codestream, often with the extension .j2k or .j2c, starts with the markers FF 4F FF 51. Part 2 extensions use .jpx (or .jpf), and Motion JPEG 2000 uses .mj2.

Adoption

JPEG 2000 is used in digital cinema packages, medical imaging (DICOM), satellite and geospatial imagery, and by libraries and archives as a preservation and access format for digitized material. It is also an image compression option in PDF. Browser support is limited, so it is rarely used for general web images. Common implementations include the open source OpenJPEG library and the commercial Kakadu toolkit.

Preservation And Security Notes

Record whether a file uses reversible (lossless) or irreversible (lossy) wavelet filters, the number of decomposition levels, tiling, and color specification. Decoders should validate box lengths, tile sizes, and component counts, because the format is flexible and parsers have historically had memory-safety bugs.

Further Reading

  • JPEG 2000 overview (JPEG committee): https://jpeg.org/jpeg2000/
  • Library of Congress format description: https://www.loc.gov/preservation/digital/formats/fdd/fdd000138.shtml