MrSID

MrSID, short for Multiresolution Seamless Image Database, is a proprietary raster image compression format and file format designed for geospatial imagery such as aerial photographs and satellite scenes. Developed by LizardTech, it enables large datasets to be compressed and displayed efficiently, often enabling fast panning and zooming over topographic maps and basemaps.

MrSID files typically use the .sid extension. The format supports multi-resolution tiling, allowing progressive rendering, a feature valuable for web mapping and GIS where bandwidth or memory is a constraint.

Technical approach: MrSID employs a wavelet-based compression scheme combined with block tiling and metadata to achieve high compression ratios while preserving important details. It provides both lossy and lossless options depending on quality settings and preserves georeferencing information and coordinate reference system data.

Software and licensing: MrSID images are supported by a range of GIS tools, often via a licensed decoder from LizardTech. Creation of MrSID files is typically done with LizardTech's GeoExpress or related tools, and distribution may require licensing. Open-source support is limited due to patents and licensing restrictions.

Adoption and context: While newer formats such as JPEG2000 and cloud-optimized GeoTIFF have gained prominence, MrSID remains in use in many agencies and legacy datasets due to its strong compression and fast display characteristics. It competes with ECW and other proprietary codecs in the geospatial imagery market.