Spatial morphological Grey Dilation filter

Spatial morphological Grey Dilation filter. See Wikipedia for general information.

The filter operates by moving a structuring element, which is a predefined shape such as a square or a circle, across the image. The structuring element defines the neighborhood around each pixel that will be considered during the dilation operation.

For each pixel in the image, the grey dilation filter finds the maximum pixel value within the structuring element’s neighborhood and assigns this maximum value to the corresponding pixel in the output image.

Usage:

  1. Start the algorithm from the Processing Toolbox panel.

  2. Select the raster to process and modify the parameterization if necessary, then click run.

    usr_section/usr_manual/processing_algorithms/convolution__morphology_and_filtering/source/usr_section/usr_manual/processing_algorithms_includes/convolution__morphology_and_filtering/img/dilation_filter_interface.png
  3. Processed image in comparison to the original.

    usr_section/usr_manual/processing_algorithms/convolution__morphology_and_filtering/source/usr_section/usr_manual/processing_algorithms_includes/convolution__morphology_and_filtering/img/dilation_filter_result.png

Parameters

Raster layer [raster]

Raster layer to be processed band-wise.

Function [string]

Python code. See grey_dilation, generate_binary_structure, iterate_structure for information on different parameters.

Default:

from scipy.ndimage import grey_dilation, generate_binary_structure, iterate_structure

structure = generate_binary_structure(rank=2, connectivity=1)
structure = iterate_structure(structure=structure, iterations=1)
function = lambda array: grey_dilation(array, structure=structure)

Outputs

Output raster layer [rasterDestination]

Raster file destination.

Command-line usage

>qgis_process help enmapbox:SpatialMorphologicalGreyDilationFilter:

----------------
Arguments
----------------

raster: Raster layer
    Argument type:  raster
    Acceptable values:
            - Path to a raster layer
function: Function
    Default value:  from scipy.ndimage import grey_dilation, generate_binary_structure, iterate_structure

structure = generate_binary_structure(rank=2, connectivity=1)
structure = iterate_structure(structure=structure, iterations=1)
function = lambda array: grey_dilation(array, structure=structure)
    Argument type:  string
    Acceptable values:
            - String value
            - field:FIELD_NAME to use a data defined value taken from the FIELD_NAME field
            - expression:SOME EXPRESSION to use a data defined value calculated using a custom QGIS expression
outputRaster: Output raster layer
    Argument type:  rasterDestination
    Acceptable values:
            - Path for new raster layer

----------------
Outputs
----------------

outputRaster: <outputRaster>
    Output raster layer