This task applies a Lee adaptive filter to smooth noisy data that has an additive component.
Lee filtering is a standard deviation-based (sigma) filter that filters data based on statistics calculated within individual filter windows. Unlike a typical low-pass smoothing filter, the Lee filter and other similar sigma filters preserve image sharpness and detail while suppressing noise. The filtered pixel is replaced by a value calculated using the surrounding pixels.
Reference: Lee, Jong-Sen, “Digital Image Enhancement and Noise Filtering by Use of Local Statistics,” IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol PAMI-2, No.2, March 1980, pp. 165-168.
Example
e = ENVI()
File = Filepath('qb_boulder_msi', Subdir=['data'], $
Root_Dir=e.Root_Dir)
Raster = e.OpenRaster(File)
Task = ENVITask('AdditiveLeeAdaptiveFilter')
Task.INPUT_RASTER = Raster
Task.WINDOW_SIZE = 5
Task.NOISE_STANDARD_DEVIATION = 0.015
Task.Execute
DataColl = e.Data
DataColl.Add, Task.OUTPUT_RASTER
View = e.GetView()
Layer = View.CreateLayer(Task.OUTPUT_RASTER)
Syntax
Result = ENVITask('AdditiveLeeAdaptiveFilter')
Input parameters (Set, Get): INPUT_RASTER, NOISE_STANDARD_DEVIATION, OUTPUT_RASTER_URI, WINDOW_SIZE
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
INPUT_RASTER (required)
Specify a raster on which to perform additive Lee adaptive filtering.
NOISE_STANDARD_DEVIATION (optional)
Specify the noise standard deviation. The default value is 0.25.
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 parameter, or set it to an exclamation symbol (!), ENVI creates a temporary file.
- 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.
WINDOW_SIZE (optional)
Specify a square filtering window size, in pixels. The default value is 3.
Output Parameters
OUTPUT_RASTER
This is a reference to the output raster of filetype ENVI.
Methods
Execute
Parameter
ParameterNames
Properties
DESCRIPTION
DISPLAY_NAME
NAME
REVISION
TAGS
Version History
See Also
ENVITask, ENVISubsetRaster, AdditiveMultiplicativeLeeAdaptiveFilter Task, BitErrorAdaptiveFilter Task, EnhancedFrostAdaptiveFilter Task, EnhancedLeeAdaptiveFilter Task, FrostAdaptiveFilter Task, GammaAdaptiveFilter Task, KuanAdaptiveFilter Task, LocalSigmaAdaptiveFilter Task, MultiplicativeLeeAdaptiveFilter Task, Masking Support in ENVITasks