AdditiveMultiplicativeLeeAdaptiveFilter Task

This task applies a Lee adaptive filter to smooth noisy data that has both an additive and a multiplicative 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

; 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('AdditiveMultiplicativeLeeAdaptiveFilter')

; Define input raster

Task.INPUT_RASTER = Raster

; Define noise_variance

Task.NOISE_STANDARD_DEVIATION = 0.5

; Define additive_noise_mean

Task.ADDITIVE_NOISE_MEAN = 1.5

; Define multiplicative_noise_mean

Task.MULTIPLICATIVE_NOISE_MEAN = 1.5

; 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('AdditiveMultiplicativeLeeAdaptiveFilter')

Input parameters (Set, Get): ADDITIVE_NOISE_MEAN, INPUT_RASTER, MULTIPLICATIVE_NOISE_MEAN, 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

ADDITIVE_NOISE_MEAN (optional)

Specify the additive noise mean. The default value is 0.

INPUT_RASTER (required)

Specify a raster on which to perform additive and multiplicative Lee adaptive filtering.

MULTIPLICATIVE_NOISE_MEAN (optional)

Specify the multiplicative noise mean. The default value is 1.0.

NOISE_STANDARD_DEVIATION (required)

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.