RasterPaletteResolver

Resolves the palette(s) on a raster by replacing cell values with their corresponding palette values. Palette values with multiple components, such as RGB, are broken down and the individual values assigned to multiple, newly-added bands.

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Typical Uses

  • Applying palette values to cells to meet format or processing requirements.
  • Preparing rasters with palettes to be written to formats that do not support palettes.

How does it work?

The RasterPaletteResolver receives raster features and, for all selected bands, resolves palette values onto bands by replacing cell values with their corresponding palette values. Palettes are removed from the output raster features.

If the palette values have multiple parts, as in RGB palettes, each component part is placed on a separate band, with new bands added as necessary to accommodate them. For example, an input raster feature that has one band with an RGB24 palette will produce an output raster feature with three bands - RED8, GREEN8, and BLUE8 - and no palettes.

This transformer supports raster band selection only. All palettes on the selected band(s) will be resolved. The RasterSelector can be used to modify selection.

If more than one palette is to be resolved, additional bands are added. Band order will reflect the original palette order.

String palettes cannot be resolved, as cell values must be numeric. They should be removed prior to the RasterPaletteResolver, using a RasterSelector and RasterPaletteRemover.

Examples

Usage Notes

  • New bands duplicate most properties of the original band, including Nodata Value, which may need to be removed or altered after palettes are resolved by using a RasterBandNodataRemover or RasterBandNodataSetter.
  • String palettes cannot be resolved and must be removed from selected bands prior to using this transformer, but they may be preserved by using a RasterPaletteExtractor to extract them (as a string) to an attribute That attribute may also be written to a file using an AttributeFileWriter.

Choosing a Raster Transformer

FME has an extensive selection of transformers for working with raster data. They can be generally categorized as working with whole rasters, bands, cells or palettes, and those designed for workflow control or combining raster with vector data.

For information on raster geometry and properties, see Rasters (IFMERaster).

Configuration

Input Ports

Output Ports

Parameters

This transformer has no parameters.

Editing Transformer Parameters

Using a set of menu options, transformer parameters can be assigned by referencing other elements in the workspace. More advanced functions, such as an advanced editor and an arithmetic editor, are also available in some transformers. To access a menu of these options, click beside the applicable parameter. For more information, see Transformer Parameter Menu Options.

Defining Values

There are several ways to define a value for use in a Transformer. The simplest is to simply type in a value or string, which can include functions of various types such as attribute references, math and string functions, and workspace parameters. There are a number of tools and shortcuts that can assist in constructing values, generally available from the drop-down context menu adjacent to the value field.

Dialog Options - Tables

Transformers with table-style parameters have additional tools for populating and manipulating values.

Reference

Processing Behavior

Feature-Based

Feature Holding

No

Dependencies None
Aliases  
History  

FME Community

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Examples may contain information licensed under the Open Government Licence – Vancouver and/or the Open Government Licence – Canada.