# JP2OpenJPEG --- JPEG2000 driver based on OpenJPEG library

This driver is an implementation of a JPEG2000 reader/writer based on OpenJPEG library v2.

For GDAL 1.11 or later, use openjpeg 2.X. For GDAL 2.3, use openjpeg >= 2.1

The driver uses the VSI Virtual File API, so it can read JPEG2000 compressed NITF files.

XMP metadata can be extracted from JPEG2000 files, and will be stored as XML raw content in the xml:XMP metadata domain.

The driver supports writing georeferencing information as GeoJP2 and GMLJP2 boxes.

Starting with GDAL 2.0, the driver supports creating files with transparency, arbitrary band count, and adding/reading metadata. Update of georeferencing or metadata of existing file is also supported. Optional intellectual property metdata can be read/written in the xml:IPR box.

## 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.

## Thread support

By default, if the JPEG2000 file has internal tiling, GDAL will try to decode several tiles in multiple threads if the RasterIO() request it receives intersect several tiles. This behaviour can be controlled with the GDAL_NUM_THREADS configuration option that defaults to ALL_CPUS in that context. In case RAM is limited, it can be needed to set this configuration option to 1 to disable multi-threading

Starting with OpenJPEG 2.2.0, multi-threading decoding can also be enabld at the code-block level. This must be enabled with the OPJ_NUM_THREADS environment variable (note: this is a system environment variable, not a GDAL configuration option), which can be set to a numeric value or NUM_CPUS. Its default value is 1. Starting with GDAL 2.3, this multi-threading at code-block level is automatically enabled by GDAL

Both multi-threading mechanism can be combined together.

## 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.

- USE_TILE_AS_BLOCK=YES/NO: (GDAL > 2.2) Whether to always use the JPEG-2000 block size as the GDAL block size Defaults to NO. Setting this option can be useful when doing whole image decompression and the image is single-tiled. Note however that the tile size must not exceed 2 GB since that's the limit supported by GDAL.

## Creation Options

- CODEC=JP2/J2K : JP2 will add JP2 boxes around the codestream data. The value is determined automatically from the file extension. If it is neither JP2 nor J2K, J2K codec is used.

- GMLJP2=YES/NO: (Starting with GDAL 1.10) 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. Defaults to YES.

- GMLJP2V2_DEF=filename: (Starting with GDAL 2.0) Indicates whether a GML box conforming to the OGC GML in JPEG2000, version 2.0.1 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 below section 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. Note: GDAL 2.0 and 2.1 use the older OGC GML in JPEG2000, version 2.0 specification, that differ essentially by the content of the gml:domainSet, gml:rangeSet and gmlcov:rangeType elements of gmljp2:GMLJP2CoverageCollection.

- GeoJP2=YES/NO: (Starting with GDAL 1.10) Indicates whether a UUID/GeoTIFF box conforming to the GeoJP2 (GeoTIFF in JPEG2000) specification should be included in the file. Defaults to YES.

- QUALITY=float_value,float_value,... : Percentage between 0 and 100. A value of 50 means the file will be half-size in comparison to uncompressed data, 33 means 1/3, etc.. Defaults to 25 (unless the dataset is made of a single band with color table, in which case the default quality is 100). Starting with GDAL 2.0, it is possible to specify several quality values (comma separated) to ask for several quality layers. Quality values should be increasing.

- REVERSIBLE=YES/NO : YES means use of reversible 5x3 integer-only filter, NO use of the irreversible DWT 9-7. Defaults to NO (unless the dataset is made of a single band with color table, in which case reversible filter is used).

- RESOLUTIONS=int_value : Number of resolution levels. Default value is selected such the smallest overview of a tile is no bigger than 128x128.

- BLOCKXSIZE=int_value : Tile width. Defaults to 1024.

- BLOCKYSIZE=int_value : Tile height. Defaults to 1024.

- PROGRESSION=LRCP/RLCP/RPCL/PCRL/CPRL : Progession order. Defaults to LRCP.

- SOP=YES/NO : YES means generate SOP (Start Of Packet) marker segments. Defaults to NO.

- EPH=YES/NO : YES means generate EPH (End of Packet Header) marker segments. Defaults to NO.

- YCBCR420=YES/NO : (GDAL >= 1.11) YES if RGB must be resampled to YCbCr 4:2:0. Defaults to NO.

- YCC=YES/NO : (GDAL >= 2.0) YES if RGB must be transformed to YCC color space ("MCT transform", i.e. internal transform, without visual degration). Defaults to YES.

- NBITS=int_value : (GDAL >= 2.0) Bits (precision) for sub-byte files (1-7), sub-uint16 (9-15), sub-uint32 (17-31).

- 1BIT_ALPHA=YES/NO: (GDAL >= 2.0) Whether to encode the alpha channel as a 1-bit channel (when there's an alpha channel). Defaults to NO, unless INSPIRE_TG=YES. Enabling this option might cause compatibility problems with some readers. At the time of writing, those based on the MrSID JPEG2000 SDK are unable to open such files. And regarding the ECW JPEG2000 SDK, decoding of 1-bit alpha channel with lossy/irreversible compression gives visual artifacts (OK with lossless encoding).

- ALPHA=YES/NO: (GDAL >= 2.0) Whether to force encoding last channel as alpha channel. Only useful if the color interpretation of that channel is not already Alpha. Defaults to NO.

- PROFILE=AUTO/UNRESTRICTED/PROFILE_1: (GDAL >= 2.0) Determine which codestream profile to use. UNRESTRICTED corresponds to the "Unrestricted JPEG 2000 Part 1 codestream" (RSIZ=0). PROFILE_1 corresponds to the "JPEG 2000 Part 1 Profile 1 codestream" (RSIZ=2), which add constraints on tile dimensions and number of resolutions. In AUTO mode, the driver will determine if the BLOCKXSIZE, BLOCKYSIZE, RESOLUTIONS, CODEBLOCK_WIDTH and CODEBLOCK_HEIGHT values are compatible with PROFILE_1 and advertize it in the relevant case. Note that the default values of those options are compatible with PROFILE_1. Otherwise UNRESTRICTED is advertized. Defaults to AUTO.

- INSPIRE_TG=YES/NO: (GDAL >= 2.0) Whether to use JPEG2000 features that comply with Inspire Orthoimagery Technical Guidelines. Defaults to NO. When set to YES, implies PROFILE=PROFILE_1, 1BIT_ALPHA=YES, GEOBOXES_AFTER_JP2C=YES. The CODEC, BLOCKXSIZE, BLOCKYSIZE, RESOLUTIONS, NBITS, PROFILE, CODEBLOCK_WIDTH and CODEBLOCK_HEIGHT options will be checked against the requirements and recommendations of the Technical Guidelines.

- JPX=YES/NO: (GDAL >= 2.0) Whether to advertize JPX features, and add a Reader requirement box, when a GMLJP2 box is written. Defaults to YES. This option should not be used unless compatibility problems with a reader occur.

- GEOBOXES_AFTER_JP2C=YES/NO: (GDAL >= 2.0) Whether to place GeoJP2/GMLJP2 boxes after the code-stream. Defaults to NO, unless INSPIRE_TG=YES. This option should not be used unless compatibility problems with a reader occur.

- PRECINCTS={prec_w,prec_h},{prec_w,prec_h},...: (GDAL >= 2.0) A list of {precincts width,precincts height} tuples to specify precincts size. Each value should be a multiple of 2. The maximum number of tuples used will be the number of resolutions. The first tuple corresponds to the higher resolution level, and the following ones to the lower resolution levels. If less tuples are specified, the last one is used by dividing its values by 2 for each extra lower resolution level. The default value used is {512,512},{256,512},{128,512},{64,512},{32,512},{16,512},{8,512},{4,512},{2,512}. An empty string may be used to disable precincts ( i.e. the default {32767,32767},{32767,32767}, ... will then be used).

- TILEPARTS=DISABLED/RESOLUTIONS/LAYERS/COMPONENTS: (GDAL >= 2.0) Whether to generate tile-parts and according to which criterion. Defaults to DISABLED.

- CODEBLOCK_WIDTH=int_value: (GDAL >= 2.0) Codeblock width: power of two value between 4 and 1024. Defaults to 64. Note that CODEBLOCK_WIDTH * CODEBLOCK_HEIGHT must not be greater than 4096. For PROFILE_1 compatibility, CODEBLOCK_WIDTH must not be greater than 64.

- CODEBLOCK_HEIGHT=int_value: (GDAL >= 2.0) Codeblock height: power of two value between 4 and 1024. Defaults to 64. Note that CODEBLOCK_WIDTH * CODEBLOCK_HEIGHT must not be greater than 4096. For PROFILE_1 compatibility, CODEBLOCK_HEIGHT must not be greater than 64.

- CODEBLOCK_STYLE=string: (GDAL >= 2.4 and OpenJPEG >= 2.3.0) Style of the code-block coding passes. The following 6 independent settings can be combined together (values should be comma separated):

  - BYPASS (1): enable selective arithmetic coding bypass (can substantially improve coding/decoding speed, at the expense of larger file size)
  - RESET (2): reset context probabilities on coding pass boundaries
  - TERMALL (4): enable termination on each coding pass
  - VSC (8): enable vertically causal context
  - PREDICTABLE (16): enable predictable termination (helps for error detection)
  - SEGSYM (32): enable segmentation symbols (helps for error detection)

  Instead of specifying them by text, it is also possible to give the corresponding numeric value of the global codeblock style, by adding the selected options (for example "BYPASS,TERMALL" is equivalent to "5"=1+4)

  By default, none of them are enabled. Enabling them will generally increase codestream size, but improve either coding/decoding speed or resilience/error detection.

- WRITE_METADATA=YES/NO: (GDAL >= 2.0) Whether metadata should be written, in a dedicated JP2 'xml ' box. Defaults to NO. The content of the 'xml ' box will be like:

      <GDALMultiDomainMetadata>
        <Metadata>
          <MDI key="foo">bar</MDI>
        </Metadata>
        <Metadata domain='aux_domain'>
          <MDI key="foo">bar</MDI>
        </Metadata>
        <Metadata domain='a_xml_domain' format='xml'>
          <arbitrary_xml_content>
          </arbitrary_xml_content>
        </Metadata>
      </GDALMultiDomainMetadata>

  If there are metadata domain whose name starts with "xml:BOX_", they will be written each as separate JP2 'xml ' box.

  If there is a metadata domain whose name is "xml:XMP", its content will be written as a JP2 'uuid' XMP box.

  If there is a metadata domain whose name is "xml:IPR", its content will be written as a JP2 'jp2i' box.

- MAIN_MD_DOMAIN_ONLY=YES/NO: (GDAL >= 2.0) (Only if WRITE_METADATA=YES) Whether only metadata from the main domain should be written. Defaults to NO.

- USE_SRC_CODESTREAM=YES/NO: (GDAL >= 2.0) (EXPERIMENTAL!) When source dataset is JPEG2000, whether to reuse the codestream of the source dataset unmodified. Defaults to NO. Note that enabling that feature might result in inconsistent content of the JP2 boxes w.r.t. to the content of the source codestream. Most other creation options will be ignored in that mode. Can be useful in some use cases when adding/correcting georeferencing, metadata, ... INSPIRE_TG and PROFILE options will be ignored, and the profile of the codestream will be overridden with the one specified/implied by the options (which may be inconsistent with the characteristics of the codestream).

### Lossless compression

Lossless compression can be achieved if ALL the following creation options are defined :

- QUALITY=100
- REVERSIBLE=YES
- YCBCR420=NO (which is the default)

### GMLJP2v2 definition file

A GMLJP2v2 box typically contains a GMLJP2RectifiedGridCoverage with the SRS information and geotransformation matrix. It is also possible to add metadata, vector features (GML feature collections), annotations (KML), styles (typically SLD, or other XML format) or any XML content as an extension. The value of the GMLJP2V2_DEF creation option should be a file that conforms with the below syntax (elements starting with "#" are documentation, and can be omitted):

    {
        "#doc" : "Unless otherwise specified, all elements are optional",

        "#root_instance_doc": "Describe content of the GMLJP2CoverageCollection",
        "root_instance": {
            "#gml_id_doc": "Specify GMLJP2CoverageCollection gml:id. Default is ID_GMLJP2_0",
            "gml_id": "some_gml_id",

            "#grid_coverage_file_doc": [
                "External XML file, whose root might be a GMLJP2GridCoverage, ",
                "GMLJP2RectifiedGridCoverage or a GMLJP2ReferenceableGridCoverage.",
                "If not specified, GDAL will auto-generate a GMLJP2RectifiedGridCoverage" ],
            "grid_coverage_file": "gmljp2gridcoverage.xml",

            "#grid_coverage_range_type_field_predefined_name_doc": [
                "New in GDAL 2.2",
                "One of Color, Elevation_meter or Panchromatic ",
                "to fill gmlcov:rangeType/swe:DataRecord/swe:field",
                "Only used if grid_coverage_file is not defined.",
                "Exclusive with grid_coverage_range_type_file" ],
            "grid_coverage_range_type_field_predefined_name": "Color",

            "#grid_coverage_range_type_file_doc": [
                "New in GDAL 2.2",
                "File that is XML content to put under gml:RectifiedGrid/gmlcov:rangeType",
                "Only used if grid_coverage_file is not defined.",
                "Exclusive with grid_coverage_range_type_field_predefined_name" ],
            "grid_coverage_range_type_file": "grid_coverage_range_type.xml",

            "#crs_url_doc": [
                "true for http://www.opengis.net/def/crs/EPSG/0/XXXX CRS URL.",
                "If false, use CRS URN. Default value is true",
                "Only taken into account for a auto-generated GMLJP2RectifiedGridCoverage"],
            "crs_url": true,

            "#metadata_doc": [ "An array of metadata items. Can be either strings, with ",
                               "a filename or directly inline XML content, or either ",
                               "a more complete description." ],
            "metadata": [

                "dcmetadata.xml",

                {
                    "#file_doc": "Can use relative or absolute paths. Exclusive of content, gdal_metadata and generated_metadata.",
                    "file": "dcmetadata.xml",

                    "#gdal_metadata_doc": "Whether to serialize GDAL metadata as GDALMultiDomainMetadata",
                    "gdal_metadata": false,

                    "#dynamic_metadata_doc":
                        [ "The metadata file will be generated from a template and a source file.",
                          "The template is a valid GMLJP2 metadata XML tree with placeholders like",
                          "{{{XPATH(some_xpath_expression)}}}",
                          "that are evaluated from the source XML file. Typical use case",
                          "is to generate a gmljp2:eopMetadata from the XML metadata",
                          "provided by the image provider in their own particular format." ],
                    "dynamic_metadata" :
                    {
                        "template": "my_template.xml",
                        "source": "my_source.xml"
                    },

                    "#content": "Exclusive of file. Inline XML metadata content",
                    "content": "<gmljp2:metadata>Some simple textual metadata</gmljp2:metadata>",

                    "#parent_node": ["Where to put the metadata.",
                                     "Under CoverageCollection (default) or GridCoverage" ],
                    "parent_node": "CoverageCollection"
                }
            ],

            "#annotations_doc": [ "An array of filenames, either directly KML files",
                                  "or other vector files recognized by GDAL that ",
                                  "will be translated on-the-fly as KML" ],
            "annotations": [
                "my.kml"
            ],

            "#gml_filelist_doc" :[
                "An array of GML files or vector files that will be on-the-fly converted",
                "to GML 3.2. Can be either GML filenames (or other OGR datasource names), ",
                "or a more complete description" ],
            "gml_filelist": [

                "my.gml",

                "my.shp",

                {
                    "#file_doc": "OGR datasource. Can use relative or absolute paths. Exclusive of remote_resource",
                    "file": "converted/test_0.gml",

                    "#remote_resource_doc": "URL of a feature collection that must be referenced through a xlink:href",
                    "remote_resource": "http://svn.osgeo.org/gdal/trunk/autotest/ogr/data/expected_gml_gml32.gml",

                    "#namespace_doc": ["The namespace in schemaLocation for which to substitute",
                                      "its original schemaLocation with the one provided below.",
                                      "Ignored for a remote_resource"],
                    "namespace": "http://example.com",

                    "#schema_location_doc": ["Value of the substituted schemaLocation. ",
                                             "Typically a schema box label (link)",
                                             "Ignored for a remote_resource"],
                    "schema_location": "gmljp2://xml/schema_0.xsd",

                    "#inline_doc": [
                        "Whether to inline the content, or put it in a separate xml box. Default is true",
                        "Ignored for a remote_resource." ],
                    "inline": true,

                    "#parent_node": ["Where to put the FeatureCollection.",
                                     "Under CoverageCollection (default) or GridCoverage" ],
                    "parent_node": "CoverageCollection"
                }
            ],

            "#styles_doc": [ "An array of styles. For example SLD files" ],
            "styles" : [
                {
                    "#file_doc": "Can use relative or absolute paths.",
                    "file": "my.sld",

                    "#parent_node": ["Where to put the FeatureCollection.",
                                     "Under CoverageCollection (default) or GridCoverage" ],
                    "parent_node": "CoverageCollection"
                }
            ],

            "#extensions_doc": [ "An array of extensions." ],
            "extensions" : [
                {
                    "#file_doc": "Can use relative or absolute paths.",
                    "file": "my.xml",

                    "#parent_node": ["Where to put the FeatureCollection.",
                                     "Under CoverageCollection (default) or GridCoverage" ],
                    "parent_node": "CoverageCollection"
                }
            ]
        },

        "#boxes_doc": "An array to describe the content of XML asoc boxes",
        "boxes": [
            {
                "#file_doc": "can use relative or absolute paths. Required",
                "file": "converted/test_0.xsd",

                "#label_doc": ["the label of the XML box. If not specified, will be the ",
                              "filename without the directory part." ],
                "label": "schema_0.xsd"
            }
        ]
    }

Metadata can be dynamically generated from a template file (in that context, with a XML structure) and a XML source file. The template file is processed by searching for patterns like {{{XPATH(xpath_expr)}}} and replacing them by their evaluation against the content of the source file. xpath_expr must be a XPath 1.0 compatible expression, with the addition of the following functions :

- if(cond_expr,expr_if_true,expr_if_false): if cond_expr evaluates to true, returns expr_if_true. Otherwise returns expr_if_false
- uuid(): evaluates to a random UUID

A template file to process XML metadata of Pleiades imagery can be found here, and a template file to process XML metadata of GeoEye/WorldView imagery can be found here.

## Vector information

Starting with GDAL 2.0, a JPEG2000 file containing a GMLJP2 v2 box with GML feature collections and/or KML annotations embedded can be opened as a vector file with the OGR API. For example:

    ogrinfo -ro my.jp2

    INFO: Open of my.jp2'
          using driver `JP2OpenJPEG' successful.
    1: FC_GridCoverage_1_rivers (LineString)
    2: FC_GridCoverage_1_borders (LineString)
    3: Annotation_1_poly

Feature collections can be linked from the GMLJP2 v2 box to a remote location. By default, the link is not followed. It will be followed if the open option OPEN_REMOTE_GML is set to YES.

## See Also:

- Implemented as `gdal/frmts/openjpeg/openjpegdataset.cpp`.

- Official JPEG-2000 page

- The OpenJPEG library home page

- OGC GML in JPEG2000, version 2.0 (GDAL 2.0 and 2.1)

- OGC GML in JPEG2000, version 2.0.1 (GDAL 2.2 and above)

- Inspire Data Specification on Orthoimagery - Technical Guidelines

Other JPEG2000 GDAL drivers :

- JPEG2000: based on Jasper library (open source)

- JP2ECW: based on Erdas ECW library (proprietary)

- JP2MRSID: based on LizardTech MrSID library (proprietary)

- JP2KAK: based on Kakadu library (proprietary)