JPEG 2000 (GeoJP2/GMLJP2) Writer: Feature Type Parameters

To access feature type parameters, click the gear icon on a feature type in the workspace. This opens the Feature Type Parameter Editor.

Tip  To always display the editor in FME Workbench, you can select View > Windows > Parameter Editor.

General

All feature types share similar General parameters, which may include Feature Type Name, Reader or Writer information, and Geometry.

In most Writer Feature Type parameter dialogs, you can also control Dynamic Schema Definitions. Some database formats accept Table or Index Qualifier prefixes on the output table feature type.

Format Parameters

The JPEG2000 writer supports the following option through the Feature Type dialog:

Compress by Percentage (0 - 99)

This option sets the desired compression level of the output image. This is expressed as a percentage of the original file size. For example, setting a compression level of 75 means that the output image will be approximately 75% smaller (one-quarter of the size) than an uncompressed image.

Note that this value only represents the targeted compression level, and this may not actually be achieved. JPEG supports both lossy and lossless compression. With lossy compression, the compressed image is an approximation of the original. With lossless compression, the compressed image is identical to the original.

Note  Repeatedly reading and saving files may decrease the quality for this format. In addition, FME Workbench may not know which format data comes from, and whether it used lossy compression. If you know that source data comes from files with lossy compression, you should also set the compression level to 0. Although this compression still does not guarantee the exact copy of the source file, the output will be very close to the original.

Number of Columns/Rows Per Tile – Specifies the tile size.

Note that the selected Encoding Profile may impose restrictions on the tile size.

  • Profile 0 requires square tiles that are powers of 2 with a minimum size of 64x64 and a maximum size of 128x128, or one tile for the whole image.

  • Profile 1 requires square tiles that are powers of 2 with a minimum size of 64x64 and a maximum size of 1024x1024, or one tile for the whole image.

Note that when using high compression levels, selecting a larger tile size may produce smaller files (in terms of file size) that are more accurate (visually) and can be read faster.

This option allows writing custom GMLJP2 data. If not specified, default GMLJP2 data will be written based on the raster properties.

The Root Instance must contain a gmljp2:GMLJP2RectifiedGridCoverage element, according to the GMLJP2 standard.

The Instance Data contains the names and values of any additional GML data, such as XML schemas, CRS dictionaries, or units of measure dictionaries. These must be set to list attributes.

Encoding Profile

Particular implementations of JPEG 2000 core coding may be established as profiles. This parameter specifies which encoding profile to use.

NATO and NGA (National Geospatial-Intelligence Agency) have established profiles for certain work flows:

  • NPJE (NSIF/BIIF/NITF Preferred JPEG 2000 Encoding), which is optimized for fast image browsing and panning at high resolutions. This is the default.
  • EPJE (Exploitation Preferred JPEG Encoding), which is optimized for viewing imagery at low resolution.

Profile 0, 1, and 2 are part of the JPEG 2000 standard:

  • Profile 0 has some restricted features, and is suitable for mobile devices. It has the greatest compatibility.
  • Profile 1 is only slightly limited from JPEG 2000, and suitable for commercial applications.
  • Profile 2 codestreams have no constraints.

Number of Layers

The coded data of each code-block is distributed across one or more layers in the codestream. Each layer successively and monotonically improves the image quality. This attribute specifies the number of layers to generate.