JPEG2000 for Geospatial Imaging

The JPEG2000 standard facilitates efficient scaling of the compressed code stream to provide image distribution and formatting that best matches the target display device. The parsable and scalable feature of JPEG2000 encoded imagery makes it particularly useful for compression and distribution of geospatial data.

The US National Imagery and Mapping Agency (NIMA) and NATO have embraced JPEG2000 as the preferred compression format for all new imagery systems.

A JPEG2000 Profile

The Basic Image Interchange Format (BIIF) includes a profile for the JPEG2000 standard. A JPEG2000 profile is a set of image encoding/decoding parameters that are designed to best serve the image management needs of a particular user group that sponsors the profile through the ISO/IEC.

As described in the standard document (ISO/IEC BIIF Profile BPJ2K01.00), "BIIF provides a file format that is suitable for the interchange, storage, and retrieval of map and imagery information." The JPEG2000 profile for BIIF, also known as BPJ2K "…tailors JPEG2000 to promote a high degree of interoperability…" between disparate systems and users.

This JPEG200 profile is used by NATO and is called the "NATO Secondary Image Format (NISF)." It is also used by NIMA (National Imagery and Mapping Agency) which includes it as part of its NITF standard (National Imagery Transmission Format).

This same profile, used by NIMA and by NATO, is perhaps best described by another acronym- NPJE- "NSIF/BIIF/NITF Preferred JPEG2000 Encoding."

The Aware JPEG2000 API is a highly-optimized, fully-compliant implementation of the JPEG2000 standard. It is a professionally designed API (Application Programming Interface) and software architecture supports the encoding, decoding and reformatting (transcoding) options defined in the NPJE profile.

Codestream Reformatting

The Aware J2K Image Object supports reformatting of the JPEG2000 code streams to change progression order, compression ratio, tile sizes and other part I encoding options without decompressing and recompressing the JPEG2000 image file.

Specific Features of the Aware JPEG2000 API

• Support for all JPEG2000 part 1 encoding options. The API includes over 90 functions.

• Support for all of the specific encoding options in the NIMA/NATO NPJE profile. This includes stand-alone tile parts, "quality" layers, packet size, number of subbands, tile offsets, TLM markers and PLT markers.

• Support for specific bit-rates (compression ratio) for each quality layer.

• Support for multiple channels. As defined in the standard, the Aware J2K API supports up 4096 channels at 16 bits/channel.

• Support for codestream reformatting, also known as "repackaging," or "transcoding." Reformatting is managed by the Aware J2K Image Object (see diagram x) and describes a process by which the file is reordered or reformatted without decompressing and recompressing the image. Reformatting of the data reduces computational complexity, and eliminates the incremental degradation of the image through multiple lossy compression and decompression steps.

• Extraction/decode/display of any resolution level and any quality level for any full image, any tile, or any group of tiles.

• Spatial Chipping at tile boundaries: any group of tiles, including irregular shaped regions can be removed as standalone/decodable and viewable images or groups of images.

• Spatial Chipping off-tile boundaries: The Aware library supports the encoding and decoding of images with what the JPEG2000 standards calls precincts. Precincts are rectangular regions that cross code blocks and tile boundaries and facilitate the process of chipping images at arbitrary, non-tile boundary based, regions.

• Fully compliant with Part IV of the JPEG2000 standard. The Aware J2K API fully decodes all compliance images.

• Supports all Windows OS variants, Linux, Solaris, Mercury OS and others as requested. The Aware J2K API supports C and Java.

For more information about Aware's JPEG2000 for Geospatial Imaging, contact us today.