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 parameters (Set, Get): GAIN, INPUT_RASTER, OFFSET, OUTPUT_RASTER_URI

Output parameters (Get only): OUTPUT_RASTER

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

Input Parameters

GAIN (required)

Specify the data gain values that will be applied to the raster. If the array contains a single value, it is applied to all bands. Otherwise, it must contain the same number of elements as there are bands in the input raster.

INPUT_RASTER (required)

Specify the raster to apply the gain and offset.

OFFSET (required)

Specify the data offset values that will be applied to the raster. If the array contains a single value, it is applied to all bands. Otherwise, it must contain the same number of elements as there are bands in the input raster.

OUTPUT_RASTER_URI (optional)

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

If you set this parameter to an asterisk symbol (*), the output raster will be virtual and not written to disk.
If you do not specify this parameter, or set it to an exclamation symbol (!), a temporary file will be created.
If you set it to the hash symbol (#), ENVI creates a file in the temporary directory, but this file will not be deleted when ENVI closes.