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ENVIGammaAdaptiveFilterTask

ENVIGammaAdaptiveFilterTask

This task applies a gamma filter to a raster, to reduce speckle while preserving edges in radar images. Filtered pixels are replaced with values calculated from local statistics.

Reference: Zhenghao Shi, and Ko B. Fung. "A Comparison of Digital Speckle Filters." Proceedings of IGRASS 94, August 8-12, 1994, pp. 2129-2133.

Example


; Start the application
e = ENVI()
 
; Open an input file
File = Filepath('elev_t.jpg', Subdir=['examples','data'])
Raster = e.OpenRaster(File)
 
; Get the task from the catalog of ENVITasks
Task = ENVITask('GammaAdaptiveFilter')
 
; Define an input raster
Task.INPUT_RASTER = Raster
 
; Define task inputs
Task.LOOKS = 1
 
; 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('GammaAdaptiveFilter')

Input properties (Set, Get): INPUT_RASTER, LOOKS, OUTPUT_RASTER_URI, WINDOW_SIZE

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:

AddParameter

Execute

Parameter

ParameterNames

RemoveParameter

Properties


This task inherits the following properties from ENVITask:

COMMUTE_ON_DOWNSAMPLE

COMMUTE_ON_SUBSET

DESCRIPTION

DISPLAY_NAME

NAME

REVISION

TAGS

This task also contains the following properties:

INPUT_RASTER (required)

Specify a raster on which to perform gamma adaptive filtering.

LOOKS (optional)

Specify the effective number of looks. The default value is 1. This property is used to calculate the noise variance by 1/(number of looks).

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.

WINDOW_SIZE (optional)

Specify a square filtering window size. The default value is 3.

Version History


ENVI 5.3

Introduced

API Version


3.3

See Also


ENVITask, ENVITask::Parameter, ENVISubsetRaster, ENVIAdditiveLeeAdaptiveFilterTask, ENVIAdditiveMultiplicativeLeeAdaptiveFilterTask, ENVIEnhancedFrostAdaptiveFilterTask, ENVIEnhancedLeeAdaptiveFilterTask, ENVIFrostAdaptiveFilterTask, ENVIBitErrorAdaptiveFilterTask, ENVIKuanAdaptiveFilterTask, ENVILocalSigmaAdaptiveFilterTask, ENVIMultiplicativeLeeAdaptiveFilterTask

 



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