# JPEG2000 --- Implementation of the JPEG-2000 part 1

This implementation based on JasPer software (see below).

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.

## Georeferencing

Georeferencing information can come from different sources : internal (GeoJP2 or GMLJP2 boxes), worldfile .j2w/.wld sidecar files, or PAM (Persitant Auxiliary metadata) .aux.xml sidecar files. By default, information is fetched in following order (first listed is the most prioritary): PAM, GeoJP2, GMLJP2, WORLDFILE.

Starting with GDAL 2.2, the allowed sources and their priority order can be changed with the GDAL_GEOREF_SOURCES configuration option (or GEOREF_SOURCES open option) whose value is a comma-separated list of the following keywords : PAM, GEOJP2, GMLJP2, INTERNAL (shortcut for GEOJP2,GMLJP2), WORLDFILE, NONE. First mentioned sources are the most prioritary over the next ones. A non mentioned source will be ignored.

For example setting it to "WORLDFILE,PAM,INTERNAL" will make a geotransformation matrix from a potential worldfile prioritary over PAM or internal JP2 boxes. Setting it to "PAM,WORLDFILE,GEOJP2" will use the mentioned sources and ignore GMLJP2 boxes.

## Option Options

(GDAL >= 2.0 ) The following open option is available:

- 1BIT_ALPHA_PROMOTION=YES/NO: Whether a 1-bit alpha channel should be promoted to 8-bit. Defaults to YES.

- GEOREF_SOURCES=string: (GDAL > 2.2) Define which georeferencing sources are allowed and their priority order. See Georeferencing paragraph.

## Creation Options

- WORLDFILE=ON: Force the generation of an associated ESRI world file (.wld).

- FORMAT=JP2|JPC: Specify output file format.

- GMLJP2=YES/NO: (Starting with GDAL 2.0) Indicates whether a GML box conforming to the OGC GML in JPEG2000 specification should be included in the file. Unless GMLJP2V2_DEF is used, the version of the GMLJP2 box will be version 1. As implemented currently, the GMLJP2 box will be written after the codestream. Defaults to YES.

- GMLJP2V2_DEF=filename: (Starting with GDAL 2.0) Indicates whether a GML box conforming to the OGC GML in JPEG2000, version 2 specification should be included in the file. filename must point to a file with a JSon content that defines how the GMLJP2 v2 box should be built. See GMLJP2v2 definition file section in documentation of the JP2OpenJPEG driver for the syntax of the JSon configuration file. It is also possible to directly pass the JSon content inlined as a string. If filename is just set to YES, a minimal instance will be built. As implemented currently, the GMLJP2 box will be written after the codestream.

- GeoJP2=YES/NO: (Option starting with GDAL 2.0, but already enabled in previous versions. Require a modified Jasper with GeoJP2 support enabled) Indicates whether a UUID/GeoTIFF box conforming to the GeoJP2 (GeoTIFF in JPEG2000) specification should be included in the file. Defaults to YES.

- NBITS=int_value : (GDAL >= 2.3) Bits (precision) for sub-byte files (1-7), sub-uint16 (9-15).

- Encoding parameters, directly delivered to the JasPer library described in the JasPer documentation. Quoted from the docs:

  ``The following options are supported by the encoder:

  imgareatlx=x | Set the x-coordinate of the top-left corner of the image area to x.
  imgareatly=y | Set the y-coordinate of the top-left corner of the image area to y.
  tilegrdtlx=x | Set the x-coordinate of the top-left corner of the tiling grid to x.
  tilegrdtly=y | Set the y-coordinate of the top-left corner of the tiling grid to y.
  tilewidth=w | Set the nominal tile width to w.
  tileheight=h | Set the nominal tile height to h.
  prcwidth=w | Set the precinct width to w. The argument w must be an integer power of two. The default value is 32768.
  prcheight=h | Set the precinct height to h. The argument h must be an integer power of two. The default value is 32768.
  cblkwidth=w | Set the nominal code block width to w. The argument w must be an integer power of two. The default value is 64.
  cblkheight=h | Set the nominal code block height to h. The argument h must be an integer power of two. The default value is 64.
  mode=m | Set the coding mode to m. The argument m must have one of the following values:
  Value | Description
  --- | ---
  int | integer mode
  real | real mode
  If lossless coding is desired, the integer mode must be used. By default, the integer mode is employed. The choice of mode also determines which multicomponent and wavelet transforms (if any) are employed.
  rate=r | Specify the target rate. The argument r is a positive real number. Since a rate of one corresponds to no compression, one should never need to explicitly specify a rate greater than one. By default, the target rate is considered to be infinite.
  ilyrrates=[, ,. . . , ] | Specify the rates for any intermediate layers. The argument to this option is a comma separated list of N rates. Each rate is a positive real number. The rates must increase monotonically. The last rate in the list should be less than or equal to the overall rate (as specified with the rate option).
  prg=p | Set the progression order to p. The argument p must have one of the following values:
  Value | Description
  --- | ---
  lrcp | layer-resolution-component-position (LRCP) progressive (i.e., rate scalable)
  rlcp | resolution-layer-component-position (RLCP) progressive (i.e., resolution scalable)
  rpcl | resolution-position-component-layer (RPCL) progressive
  pcrl | position-component-resolution-layer (PCRL) progressive
  cprl | component-position-resolution-layer (CPRL) progressive
  By default, LRCP progressive ordering is employed. Note that the RPCL and PCRL progressions are not valid for all possible image geometries. (See standard for more details.)
  nomct | Disallow the use of any multicomponent transform.
  numrlvls=n | Set the number of resolution levels to n. The argument n must be an integer that is greater than or equal to one. The default value is 6.
  sop | Generate SOP marker segments.
  eph | Generate EPH marker segments.
  lazy | Enable lazy coding mode (a.k.a. arithmetic coding bypass).
  termall | Terminate all coding passes.
  segsym | Use segmentation symbols.
  vcausal | Use vertically stripe causal contexts.
  pterm | Use predictable termination.
  resetprob | Reset the probability models after each coding pass. |
  numgbits=n | Set the number of guard bits to n.''

## See Also:

- Implemented as `gdal/frmts/jpeg2000/jpeg2000dataset.cpp`.

- You need modified JasPer library to build this driver with GeoJP2 support enabled. Modified version can be downloaded from http://download.osgeo.org/gdal/jasper-1.900.1.uuid.tar.gz

- Official JPEG-2000 page

- The JasPer Project Home Page

Other JPEG2000 GDAL drivers :

- JP2OpenJPEG: based on OpenJPEG library (open source)

- JP2ECW: based on Erdas ECW library (proprietary)

- JP2MRSID: based on LizardTech MrSID library (proprietary)

- JP2KAK: based on Kakadu library (proprietary)