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Harris Geospatial / Docs Center / ENVI API / Processing / ENVIDarkSubtractionCorrectionTask

ENVIDarkSubtractionCorrectionTask

ENVIDarkSubtractionCorrectionTask

This task performs a simple atmospheric correction by subtracting a user-specified digital number (DN) from each band to account for atmospheric scattering (haze).

Example


This example uses the minimum DN value of each band as input to dark subtraction.

  ; Start the application
  e = ENVI()
   
  ; Open an input file
  File = Filepath('qb_boulder_msi', Subdir=['data'], $
    Root_Dir=e.Root_Dir)
  Raster = e.OpenRaster(File)
   
  ; Process a spatial subset
  Subset = ENVISubsetRaster(Raster, Sub_Rect=[600,200,799,399])
   
  ; Calculate basic statistics
  Stats = ENVIRasterStatistics(Subset)
   
  ; Get the task from the catalog of ENVITasks
  Task = ENVITask('DarkSubtractionCorrection')
   
  ; Define inputs
  Task.INPUT_RASTER = Subset
  Task.VALUES = Stats.Min
   
  ; Define outputs
  Task.OUTPUT_RASTER_URI = e.GetTemporaryFilename()
   
  ; Run the task
  Task.Execute
   
  ; Get the collection of data objects currently available in the Data Manager
  DataColl = e.Data
   
  ; Add the output to the Data Manager
  DataColl.Add, Task.Output_Raster
   
  ; Display the result
  View1 = e.GetView()
  Layer1 = View1.CreateLayer(Task.Output_Raster)

Syntax


Result = ENVITask('DarkSubtractionCorrection')

Input properties (Set, Get): IGNORE_VALIDATE, INPUT_RASTER, OUTPUT_RASTER_URI, VALUES

Output properties (Get only): DESCRIPTION, NAME, 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.

Methods


This task inherits the following methods from ENVITask:

AddParameter

Execute

Parameter

ParameterNames

RemoveParameter

Properties


DESCRIPTION

This property describes the task.

IGNORE_VALIDATE (optional)

This property is now deprecated and has no effect on task behavior. All task property values are validated when they are set, and they throw an error with bad input.

INPUT_RASTER (required)

Specify a raster on which to perform dark subtraction correction.

NAME

This property contains the name of the task.

OUTPUT_RASTER

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

OUTPUT_RASTER_URI (optional)

Specify a string with the fully qualified filename and path of the output raster. If you do not specify this property, the output raster is only temporary. Once the raster has no remaining references, ENVI deletes the temporary file.

VALUES (required)

Specify a digital number (DN) value or array of DN values to subtract from each band. The number of elements in the array must match the number of bands.

Version History


ENVI 5.2

Introduced

See Also


ENVITask, ENVITaskParameter, ENVISubsetRaster



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