mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-29 17:37:20 +08:00
Vighnesh Birodkar
56 lines
1.6 KiB
Python
56 lines
1.6 KiB
Python
import networkx as nx
|
|
import numpy as np
|
|
|
|
|
|
def threshold_cut(labels, rag, thresh):
|
|
"""Combine regions seperated by weight less than threshold.
|
|
|
|
Given an image's labels and its RAG, output new labels by
|
|
combining regions whose nodes are seperated by a weight less
|
|
than the given threshold.
|
|
|
|
Parameters
|
|
----------
|
|
labels : ndarray
|
|
The array of labels.
|
|
rag : RAG
|
|
The region adjacency graph.
|
|
thresh : float
|
|
The threshold, regions with edge weights less than this
|
|
are combined.
|
|
|
|
Returns
|
|
-------
|
|
out : ndarray
|
|
The new labelled array.
|
|
|
|
Examples
|
|
--------
|
|
>>> from skimage import data, graph, segmentation
|
|
>>> img = data.lena()
|
|
>>> labels = segmentation.slic(img)
|
|
>>> rag = graph.rag_meancolor(img, labels)
|
|
>>> new_labels = graph.threshold_cut(labels, rag, 10)
|
|
|
|
References
|
|
----------
|
|
.. [1] Alain Tremeau and Philippe Colantoni
|
|
"Regions Adjacency Graph Applied To Color Image Segmentation"
|
|
http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.11.5274
|
|
|
|
"""
|
|
# Because deleting edges while iterating through them produces an error.
|
|
to_remove = [(x, y) for x, y, d in rag.edges_iter(data=True)
|
|
if d['weight'] >= thresh]
|
|
rag.remove_edges_from(to_remove)
|
|
|
|
comps = nx.connected_components(rag)
|
|
|
|
map_array = np.arange(labels.max() + 1, dtype=labels.dtype)
|
|
for i, nodes in enumerate(comps):
|
|
for node in nodes:
|
|
for label in rag.node[node]['labels']:
|
|
map_array[label] = i
|
|
|
|
return map_array[labels]
|