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 properties (Set, Get): INPUT_RASTER, NOISE_STANDARD_DEVIATION, 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 additive Lee adaptive filtering.
NOISE_STANDARD_DEVIATION (optional)
Specify the noise standard deviation. The default value is 0.25.
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, in pixels. The default value is 3.
Version History
API Version
4.3
See Also
ENVITask, ENVISubsetRaster, AdditiveMultiplicativeLeeAdaptiveFilter Task, BitErrorAdaptiveFilter Task, EnhancedFrostAdaptiveFilter Task, EnhancedLeeAdaptiveFilter Task, FrostAdaptiveFilter Task, GammaAdaptiveFilter Task, KuanAdaptiveFilter Task, LocalSigmaAdaptiveFilter Task, MultiplicativeLeeAdaptiveFilter Task