GeoExpress enables your applications to use JPEG 2000 compression on geospatial images with the same level of efficiency, metadata, and large-image support already available with MrSID. JPEG 2000 image compression offers many of the advantages implemented in the MrSID format, plus the added benefits of being an international standard (ISO/IEC 15444).
All of the basic options and some of the advanced options that are available for MrSID encoding are also available for the JPEG 2000 format. Certain advanced operations such as creating and updating composites and optimizing images are not available for JPEG 2000 encoding.
GeoExpress supports encoding JPEG 2000 files in two different modes,"GMLJP2" and "Part I". By default GeoExpress uses GMLJP2, which is the best option for most workflows. For applications that do not support GMLJP2, the Part I mode generates files that do not use any Part II extensions. GMLJP2 metadata is not available in this mode. Other encoding features, such as the use of NPJE profiles and other metadata forms, are still available. Use the Part I mode only when you are sure that the image user's workflow entails applications that cannot read GMLJP2 files.
The two modes are included as options in the Output Format drop-down list. For convenience when creating mosaics, this drop-down list also appears on the “Create New Mosaic” dialog box.
JPEG 2000 encoding utilizes the same data cartridge deduction mechanism that MrSID encoding does (see Frequently Asked Questions and Data Cartridges). Operations involving only MrSID and/or JPEG 2000 input files do not decrement the cartridge.
GeoExpress allows Geography Markup Language (GML) metadata to be added to JPEG 2000 (JP2) imagery to comply with the Open Geospatial Consortium (OGC) GMLJP2 standard.
GML (Geography Markup Language) is an open, XML-based specification for representing geographic information including geographic features, coverages, observations, topology, geometry, coordinate reference systems, units of measure, time and other values. Because it is an XML grammar, it is both extensible and adaptable to any application within the broad geospatial field.
As a wavelet-based image compression format, JPEG 2000 (JP2) is capable of handling images into the gigabyte range and beyond. But until recently, JP2 was not particularly suited to the needs of the geospatial community because it didn't have a designated geospatial metadata standard. However, because the JPEG 2000 format allows for the inclusion of XML data, GML has emerged as the ideal partner for JPEG 2000 imagery, bridging the gap between JP2 and GIS.
GMLJP2 is the specification that standardizes that partnership and opens the door for greater interoperability between your imagery and the thousands of current and future geospatial applications that might use it. Containing its own geographic metadata, your JP2 imagery becomes "spatially aware" and is thus of increased value in geospatial applications. Prior to the adoption of GMLJP2, the lack of a geospatial metadata standard meant that applications and viewers may or may not have been able to read geospatial metadata in a JPEG 2000 file.
The GMLJP2 specification was officially adopted in February 2006 by the Open Geospatial Consortium (OGC) as an open standard for representing geographic information in JPEG 2000 imagery. LizardTech supports open standards and is committed to the success of the GMLJP2 specification.
Jointly proposed and developed by LizardTech, Galdos Systems and a consortium of forward-looking aerospace and technology companies, GMLJP2 represents the most advanced means of including geographic metadata within compressed geospatial imagery and making that information useful in downstream applications now and in the future.
GeoExpress already offers the most complete and easy-to-use implementation of the open JPEG 2000 standard. Now, your JP2 imagery encoded with GMLJP2 metadata is secure for the future because, like JPEG 2000, the GMLJP2 specification is an open, non-proprietary standard.
NOTE: Some applications that support JPEG 2000 do not support all of the features that are required to implement the GMLJP2 standard. For more information, see JPEG 2000 Output Selections.
The GML option is available among the metadata control settings of the advanced JPEG 2000 options (see GMLJP2 Metadata).
Learn more about the GML and GMLJP2 specifications at http://www.opengeospatial.org/specs/?page=specs.
The GMLJP2 Application Schema version 3.1.1. can be found at http://schemas.opengis.net/gml/.
JPEG 2000 images can be created with an essentially unlimited number of bands, so multispectral output can be created from multispectral input without having to go through an output color space. For JPEG 2000 encoding, the color compositor allows multibanded images to be created from files representing individual bands.
For more information see Creating Multiband JPEG 2000 Files.