Sustainability of Digital Formats: Planning for Library of Congress Collections

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MrSID Image Format, Generation 3

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Format Description Properties Explanation of format description terms

Identification and description Explanation of format description terms

Full name MrSID Image Format (Multi-resolution Seamless Image Database), Generation 3

MrSID is a patented, wavelet-based file format designed to enable portability of massive bit-mapped (raster) images. The format employs discrete wavelet transformations (DWT) in a seamless fashion on tile subsets of the image data and stores the wavelet coefficients in a data structure that supports efficient retrieval of the data needed to generate a specified rectangular zone of the image at a chosen spatial resolution. The data structure of a MrSID image is a set of bitplanes designed to support 'transactions' of image data by extracting and delivering exactly and only those bitplanes necessary to construct a view according to desired scene, scale, or image quality, independent of bandwidth constraints. The format was designed to enable instantaneous viewing and manipulation of imagery both locally and over networks without sacrificing quality.

New features in Generation 3 of the image format include lossless compression, multiple images in a composite file, and support for selective optimization and decoding by scene or region. Also included is support for multispectral data and user-supplied color transforms (rather than the default RGB to YIQ chrominance-luminance transform).

Production phase Most often a middle-state or final-state format.
Relationship to other formats
    Has earlier version MrSID_MG2, MrSID Image Format, Generation 2
    Has later version MrSID Generation 4, not described separately at this site.

Local use Explanation of format description terms

LC experience or existing holdings The Library of Congress, as of June 2023, has about 1.8 TB of MrSID files in its collections. This is a combination of all versions of MrSID files and not specifically MrSID_MG3.
LC preference See the Library of Congress Recommended Formats Statement (RFS) for format preferences for still image works.

Sustainability factors Explanation of format description terms

Disclosure See MrSID_MG2.
    Documentation See MrSID_MG2.

As of January 2015, MrSID_MG3 is the format used for Compressed County Mosaic files distributed by the National Agriculture Imagery Program of the Farm Service Agency. See USDA/FSA Image Compression Information Sheet (2013). The Global Land Cover Facility at the University of Maryland makes Landsat GeoCover Mosaics(link via Internet Archive) from 1990 and 2000 available as MrSID files.

See also MrSID_MG2.

    Licensing and patents See MrSID_MG2.
Transparency See MrSID_MG2.
Self-documentation TBD.
External dependencies None
Technical protection considerations None

Quality and functionality factors Explanation of format description terms

Still Image
Normal rendering Good support.
Clarity (high image resolution) See MrSID_MG2. In addition, Generation 3 supports lossless compression.
Color maintenance TBD
Support for vector graphics, including graphic effects and typography No support for vector graphics.
Functionality beyond normal rendering Since MrSID is widely used for geospatial images, it incorporates metadata to support georeferencing, geo-rectification, etc. for use in GIS systems. MrSID, Generation 3 allows multiple images in a file to create composite images.

File type signifiers and format identifiers Explanation of format description terms

Tag Value Note
Filename extension sid
Internet Media Type image/x-mrsid-image
Pronom PUID fmt/392
See Pronom does not specify version of MrSID.
Wikidata Title ID Q1422885
See Wikidata does not specify version of MrSID.

Notes Explanation of format description terms

History See MrSID_MG2.

With MG4, Extensis, formerly LizardTech introduced compression for multispectral images and LiDAR point clouds. The MG4 format also added support for alpha (transparency) bands, enabling users with shapefiles defining the boundaries of their image data to perform more complex mosaicking operations than ever before.

Format specifications Explanation of format description terms

Useful references


Books, articles, etc.

Last Updated: 06/14/2023