RasterHistogram Task

This task computes a histogram for a raster.

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('RasterHistogram')

; Define inputs

Task.INPUT_RASTER = Raster

; Run the task

Task.Execute

; Display histogram results in a plot window

nbands = Task.INPUT_RASTER.nBands

color = [[!color.red],[!color.green],[!color.blue],[!color.violet]]

for band=0, nbands-1 do $

  p = plot(findgen(task.Output_nBins[band], Start=task.output_min[band], $

  increment=task.Output_BinSize[band]), (task.output_counts[band]), $

  /hist,buffer=buffer, /overplot, color=color[*,band], ytickformat='(g0)', $

  thick=2, clip=0)

Syntax

Result = ENVITask('RasterHistogram')

Input properties (Set, Get): INPUT_BINSIZE, INPUT_MAX, INPUT_MIN, INPUT_NBINS, INPUT_RASTER

Output properties (Get only): OUTPUT_BINSIZE, OUTPUT_COUNTS, OUTPUT_MAX, OUTPUT_MIN, OUTPUT_NBINS

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:

Properties

This task inherits the following properties from ENVITask:

COMMUTE_ON_DOWNSAMPLE

INPUT_BINSIZE (optional)

Specify a value for the bin size, to manage the resolution of the histogram. INPUT_BINSIZE is mutually exclusive from INPUT_NBINS.

INPUT_MAX (optional)

Specify the maximum value of the histogram for each band. Set to a scalar value that applies to all bands, or set to an array of values, one per band.

INPUT_MIN (optional)

Specify the minimum value of the histogram for each band. Set to a scalar value that applies to all bands, or set to an array of values, one per band.

INPUT_NBINS (optional)

Specify a value for the number of bins. INPUT_NBINS is mutually exclusive from INPUT_BINSIZE. If you do not specify either of these properties, a default value of 256 bins will be used for all bands.

INPUT_RASTER (required)

Specify a raster from which to generate histogram statistics.

OUTPUT_BINSIZE

This is the bin size of the histogram for each band.

OUTPUT_COUNTS

This is the pixel count of the histogram for each band.

OUTPUT_MAX

This is the maximum value of the histogram for each band.

OUTPUT_MIN

This is the minimum value of the histogram for each band.

OUTPUT_NBINS

This is the number of bins the histogram was limited to for each band.

Version History

ENVI 5.3

Introduced

API Version

4.2