This task expands the number of bands in a raster. Dimensionality expansion is a mathematical technique to increase multispectral data dimensionality in a nonlinear fashion so that standard hyperspectral linear methods can perform better at both pure-and mixed-pixel detection and classification. These hyperspectral methods include Orthogonal Subspace Projection (OSP), Constrained Energy Minimization (CEM), Matched Filter (MF), and Adaptive Coherence Estimator (ACE). The additional bands are created by computing the square roots, natural logs, auto-correlations (squares), and cross-correlations of the input bands.

The virtual raster associated with this task is ENVIDimensionalityExpansionRaster.


Chang, C.-I., J.-M. Liu, H. Ren, C.-M. Chung, C.-W. Yang, and D.-J. Ma. "Generalized Constrained Energy Minimization Approach to Subpixel Target Detection for Multispectral Imagery." Optical Engineering 39, No. 5 (2000): 1275-1281.

Heinz, D. "Constrained Least Squares Approaches to Target Detection and Image Classification for Remotely Sensed Images." Ph.D. dissertation. University of Maryland Baltimore County (2001).

Heinz, D., and C.-I. Chang. "Fully Constrained Least Squares Linear Spectral Mixture Analysis Method for Material Quantification in Hyperspectral Imagery." IEEE Transactions on Geoscience and Remote Sensing 39, No. 3 (2001): 529-545.

Heinz, D., and C.-I. Chang. "Unsupervised Fully Constrained Least Squares Linear Spectral Mixture Analysis Method for Multispectral Imagery." Proceedings of IGARSS 2000: 1681-1683.


This example creates and adds 18 new bands to a four-band multispectral raster. After the image is displayed in the view, open the Data Manager to see the additional bands.

; Start the application
e = ENVI()
; Open an input file
File = Filepath('qb_boulder_msi', Subdir=['data'], $
Raster = e.OpenRaster(File)
; Get the task from the catalog of ENVITasks
Task = ENVITask('DimensionalityExpansionRaster')
; Define inputs
Task.INPUT_RASTER = Raster
; Run the task
; Add the output to the Data Manager
e.Data.Add, Task.OUTPUT_RASTER
; Display the result
View = e.GetView()
Layer = View.CreateLayer(Task.OUTPUT_RASTER)


Result = ENVITask('DimensionalityExpansionRaster')

Input properties (Set, Get): INPUT_RASTER, OUTPUT_RASTER_URI

Output properties (Get only): OUTPUT_RASTER

Properties marked as "Set" are those that you can set to specific values. You can also retrieve their current values any time. Properties marked as "Get" are those whose values you can retrieve but not set.


This task inherits the following methods from ENVITask:







This task inherits the following properties from ENVITask:








This task also contains the following properties:

INPUT_RASTER (required)

Specify the input ENVIRaster. This task accepts an image with any number of bands, although it is best used with multispectral imagery.


This is a reference to the output raster of filetype ENVI.


Specify a string with the fully qualified filename and path to export the associated OUTPUT_RASTER.

  • If you set this property to an asterisk symbol (*), the output raster will be virtual and not written to disk.
  • If you do not specify this property, the associated output raster will not be created. To force the creation of a temporary file, set this parameter to an exclamation symbol (!).

Version History

ENVI 5.5. 2


API Version


See Also

ENVITask, ENVIDimensionalityExpansionRaster, DimensionalityExpansionSpectralLibrary Task