MrSID --- Multi-resolution Seamless Image Database
MrSID is a wavelet-based image compression technology which can utilize both
lossy and lossless encoding. This technology was acquired in its original
form from Los Alamos National Laboratories (LANL), where it was developed
under the aegis of the U.S. government for storing fingerprints for the FBI.
Now it is developed and distributed by Extensis.
This driver supports reading of MrSID image files using Extensis' decoding
software development kit (DSDK). This DSDK is not free software, you should
contact Extensis to obtain it (see link at end of this page). If you are
using GCC, please, ensure that you have the same compiler as was used
for DSDK compilation. It is C++ library, so you may get incompatibilities
in C++ name mangling between different GCC versions (2.95.x and 3.x).
Latest versions of the DSDK also support decoding JPEG2000 file format, so this driver can be used for JPEG2000 too.
Metadata
MrSID metadata transparently translated into GDAL metadata strings. Files
in MrSID format contain a set of standard metadata tags such as:
IMAGE__WIDTH (contains the width of the image), IMAGE__HEIGHT (contains the
height of the image), IMAGE__XY_ORIGIN (contains the x and y coordinates
of the origin), IMAGE__INPUT_NAME (contains the name or names of the files
used to create the MrSID image) etc. GDAL's metadata keys cannot contain
characters `:' and `=', but standard MrSID tags always contain double colons
in tag names. These characters replaced in GDAL with `_' during translation.
So if you are using other software to work with MrSID be ready that names
of metadata keys will be shown differently in GDAL.
Starting with GDAL 1.9.0, XMP metadata can be extracted from JPEG2000 files,
and will be stored as XML raw content in the xml:XMP metadata domain.
Georeference
MrSID images may contain georeference and coordinate system information in
form of GeoTIFF GeoKeys, translated in metadata records. All those GeoKeys
properly extracted and used by the driver. Unfortunately, there is one
caveat: old MrSID encoders has a bug which resulted in wrong GeoKeys, stored
in MrSID files. This bug was fixed in MrSID software version 1.5, but if you
have older encoders or files, created with older encoders, you cannot use
georeference information from them.
See Also: