ApplyGainOffset Task

This task applies custom gain and offset values to each band of a raster, updating the pixel values accordingly. The output raster can be used for a custom calibration routine.

This task is different from the RadiometricCalibration task, which applies gains and offsets automatically to common data types such as Worldview and Landsat. It then calibrates the data to radiance or reflectance.

The virtual raster associated with this task is ENVIGainOffsetRaster.

Example

; Start the application

e = ENVI()

; Open an input file

File = Filepath('bhtmref.img', $

  Subdir=['classic', 'data'], Root_Dir=e.Root_Dir)

Raster = e.OpenRaster(File)

; Get the task from the catalog of ENVITasks

Task = ENVITask('ApplyGainOffset')

; Define inputs

Task.GAIN = [2.00, 1.33, 1.20, 1.11, 2.60, 3.12]

Task.OFFSET = [12.33, 1.10, 6.00, 1.55, 5.32, 4.05]

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('ApplyGainOffset')

Input properties (Set, Get): GAIN, INPUT_RASTER, OFFSET, 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.

Methods

This task inherits the following methods from ENVITask:

Properties

This task inherits the following properties from ENVITask:

COMMUTE_ON_DOWNSAMPLE

GAIN (required)

Specify a floating-point array of data gain values, one per band, to apply to the input raster.

INPUT_RASTER (required)

Specify the raster to apply the gain and offset.

OFFSET (required)

Specify a floating-point array of data offset values, one per band, to apply to the input raster.

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 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, or set it to an exclamation symbol (!), a temporary file will be created.

Version History

ENVI 5.2. 1	Introduced
ENVI 5.5	OUTPUT_RASTER_URI now supports '*', which allows OUTPUT_RASTER to be virtual output.

API Version

4.3