MrSID
From Wikipedia, the free encyclopedia
MrSID (pronounced Mister Sid) is an acronym that stands for Multiresolution Seamless Image Database. It is a file format (*.sid) developed and patented by LizardTech.
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[edit] Common Uses
[edit] Geographic Information Systems
MrSID was developed primarily for Geographic Information Systems (GIS). With this format, massive image data can be partitioned and displayed as satellite imagery in map software.
[edit] World Wide Web
Since MrSID files contain multiple scale and quality levels they are well suited for streaming over the World Wide Web. Only the requested zoom and area of the image is sent to the browser.
[edit] Software
LizardTech offers a software package called GeoExpress to read and write MrSID files. They also provide a free web browser plug-in. Most major GIS software packages can read MrSID files including those from ESRI, Bentley Systems, MapInfo and Autodesk. Developers can use the component LEADTOOLS from LEAD Technologies to display MrSID files in their own applications.
[edit] Technology
[edit] Encoding
MrSID technology uses lossless wavelet compression to create an initial image. Then the encoder divides the image into zoom levels, subbands, subblocks and bitplanes. After the initial encoding, the image creator can apply zero or more optimizations. While 2:1 compression ratios may be achieved losslessly, higher compression rates are lossy much like JPEG-compressed data.
[edit] Decoding
MrSID uses selective decoding meaning that the decoder does not have to decode the entire file to view a specific zoom level, image quality or scene for example.
