`scipy.ndimage._morphology:grey_dilation`

source: /scipy/ndimage/_morphology.py :1292

Signature

   def     grey_dilation (    input    ,    size    =  None   ,    footprint    =  None   ,    structure    =  None   ,    output    =  None   ,    mode    =  reflect   ,    cval    =  0.0   ,    origin    =  0   ,  * ,     axes    =  None     )

Summary

Calculate a greyscale dilation, using either a structuring element, or a footprint corresponding to a flat structuring element.

Extended Summary

Grayscale dilation is a mathematical morphology operation. For the simple case of a full and flat structuring element, it can be viewed as a maximum filter over a sliding window.

Parameters

input : array_like: Array over which the grayscale dilation is to be computed.
size : tuple of ints: Shape of a flat and full structuring element used for the grayscale dilation. Optional if footprint or structure is provided.
footprint : array of ints, optional: Positions of non-infinite elements of a flat structuring element used for the grayscale dilation. Non-zero values give the set of neighbors of the center over which the maximum is chosen.
structure : array of ints, optional: Structuring element used for the grayscale dilation. structure may be a non-flat structuring element. The structure array applies an additive offset for each pixel in the neighborhood.
output : array, optional: An array used for storing the output of the dilation may be provided.
mode : {'reflect','constant','nearest','mirror', 'wrap'}, optional: The mode parameter determines how the array borders are handled, where cval is the value when mode is equal to 'constant'. Default is 'reflect'
cval : scalar, optional: Value to fill past edges of input if mode is 'constant'. Default is 0.0.
origin : scalar, optional: The origin parameter controls the placement of the filter. Default 0
axes : tuple of int or None: The axes over which to apply the filter. If None, input is filtered along all axes. If an origin tuple is provided, its length must match the number of axes.

Returns

grey_dilation : ndarray: Grayscale dilation of input.

Notes

The grayscale dilation of an image input by a structuring element s defined over a domain E is given by:

(input+s)(x) = max {input(y) + s(x-y), for y in E}

In particular, for structuring elements defined as s(y) = 0 for y in E, the grayscale dilation computes the maximum of the input image inside a sliding window defined by E.

Grayscale dilation ^[1] is a mathematical morphology operation ^[2].

Array API Standard Support

grey_dilation has experimental support for Python Array API Standard compatible backends in addition to NumPy. Please consider testing these features by setting an environment variable SCIPY_ARRAY_API=1 and providing CuPy, PyTorch, JAX, or Dask arrays as array arguments. The following combinations of backend and device (or other capability) are supported.

====================  ====================  ====================
Library               CPU                   GPU
====================  ====================  ====================
NumPy                 ✅                     n/a                 
CuPy                  n/a                   ✅                   
PyTorch               ✅                     ⛔                   
JAX                   ⚠️ no JIT             ⛔                   
Dask                  ⚠️ computes graph     n/a                 
====================  ====================  ====================

See dev-arrayapi for more information.

Examples

from scipy import ndimage
import numpy as np
a = np.zeros((7,7), dtype=int)
a[2:5, 2:5] = 1
a[4,4] = 2; a[2,3] = 3
a
ndimage.grey_dilation(a, size=(3,3))
ndimage.grey_dilation(a, footprint=np.ones((3,3)))
s = ndimage.generate_binary_structure(2,1)

✓

✗

ndimage.grey_dilation(a, footprint=s)
ndimage.grey_dilation(a, size=(3,3), structure=np.ones((3,3)))

✓

Aliases

scipy.ndimage.grey_dilation

Referenced by

Other packages

skimage skimage.morphology.gray:_patch_footprint_mirroring