LinearPercentStretchRaster Task

This task accepts a source raster and returns a raster with a linear percent stretch applied. A linear percent stretch allows you to trim extreme values from both ends of the histogram using a specified percentage.

The virtual raster associated with this task is ENVILinearPercentStretchRaster.

Example

; Start the application

e = ENVI()

; Open an input file

File = Filepath('qb_boulder_msi', Subdir=['data'], $

  Root_Dir=e.Root_Dir)

Raster = e.OpenRaster(File)

; Get the task from the catalog of ENVITasks

Task = ENVITask('LinearPercentStretchRaster')

; Define inputs

Task.INPUT_RASTER = Raster

Task.PERCENT = [5.0]

; 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('LinearPercentStretchRaster')

Input parameters (Set, Get): BRIGHTNESS, INPUT_RASTER, OUTPUT_RASTER_URI, PERCENT

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

BRIGHTNESS (optional)

Set this parameter to an integer value from 0 to 100, indicating the brightness level to display. The default value is 50 if no brightness is specified. You can also set this value to a scalar or an array with the same number of elements as the raster has bands.

INPUT_RASTER (required)

Specify a raster on which to apply the stretch.

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.

PERCENT (optional)

Specify a double-precision floating point value, or array of values, indicating the percentage of pixel values in the beginning and end of the histogram that will be clipped out when applying the stretch. Arrays must have the same number of elements as the number of bands in the source raster. The default value is 2. The valid range of values is 0 to 50.