DarkSubtractionCorrection Task

This task performs a simple atmospheric correction by subtracting a value from each band to account for atmospheric scattering (haze). The digital number (DN) to subtract from each band can be either the band minimum, an average based upon an region of interest (ROI), or a specific value. If the user does not provide an ROI or array of values, the band minimum is used.

Example

This example subtracts the band minimum DN value of each band.

  ; 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)

  ; Get the task from the catalog of ENVITasks

  Task = ENVITask('DarkSubtractionCorrection')

  ; Define inputs

  Task.INPUT_RASTER = Raster

  ; 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

  View = e.GetView()

  Layer = View.CreateLayer(Task.OUTPUT_RASTER)

Syntax

Result = ENVITask('DarkSubtractionCorrection')

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

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.

Methods

This task inherits the following methods from ENVITask:

Properties

This task inherits the following properties from ENVITask:

COMMUTE_ON_DOWNSAMPLE

INPUT_RASTER (required)

Specify a raster on which to perform dark subtraction correction.

ROI (optional)

Specify an ROI of dark regions which contain the average value to subtract from each band.

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 associated OUTPUT_RASTER. If you do not specify this property, or set it to an exclamation symbol (!), a temporary file will be created.

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
ENVI 6.1	Added the ROI keyword and default band minimum.

API Version

4.3