Sustainability of Digital Formats
Planning for Library of Congress Collections
Sustainability of Digital Formats
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| Introduction | Sustainability Factors | Content Categories | Format Descriptions | Contact | |
| Full name | MrSID Image Format (Multi-resolution Seamless Image Database), Generation 3 |
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| Description |
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 (Multi-resolution Seamless Image Database), Generation 2 |
| LC experience or existing holdings | No experience with Generation 3 of MrSID. |
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| LC preference | Neither preferred nor acceptable as a master format. |
| Disclosure | See MrSID_MG2. |
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| Documentation | See MrSID_MG2. |
| Adoption | See MrSID_MG2. |
| Licensing and patents | See MrSID_MG2. |
| Transparency | See MrSID_MG2. |
| Self-documentation | TBD. |
| External dependencies | None |
| Technical protection considerations | None |
| Still Image | |
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| Normal rendering | Good support. |
| Clarity (high image resolution) | See MrSID_MG2. In addition, Generation 3 supports lossless compression. |
| Color maintenance | TBD |
| Support for 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 geo-rectification, etc. in GIS systems. MrSID, Generation 3 allows multiple images in a file to create composite images. |
| Tag | Value | Note |
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| Filename extension | sid |
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| Internet Media Type | image/x-mrsid-image |
| General | |
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| History | See MrSID_MG2. |
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