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61 lines
2.2 KiB
Python
61 lines
2.2 KiB
Python
import numpy as np
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from scipy import ndimage as nd
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from ..morphology import dilation, erosion, square
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from ..util import img_as_float
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from ..color import gray2rgb
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from .._shared.utils import deprecated
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def find_boundaries(label_img, connectivity=1):
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"""Return bool array where boundaries between labeled regions are True.
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Parameters
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----------
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label_img : array of int
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An array in which different regions are labeled with different
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integers.
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connectivity: int in {1, ..., `label_img.ndim`}, optional
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A pixel is considered a boundary pixel if any of its neighbors
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has a different label. `connectivity` controls which pixels are
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considered neighbors. A connectivity of 1 (default) means
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pixels sharing an edge (in 2D) or a face (in 3D) will be
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considered neighbors. A connectivity of `label_img.ndim` means
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pixels sharing a corner will be considered neighbors.
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Returns
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-------
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boundaries : array of bool, same shape as `label_img`
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A bool image where `True` represents a boundary pixel.
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"""
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selem = nd.generate_binary_structure(label_img.ndim, connectivity)
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boundaries = dilation(label_img, selem) != erosion(label_img, selem)
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return boundaries
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def mark_boundaries(image, label_img, color=(1, 1, 0),
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outline_color=(0, 0, 0)):
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"""Return image with boundaries between labeled regions highlighted.
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Parameters
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----------
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image : (M, N[, 3]) array
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Grayscale or RGB image.
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label_img : (M, N) array
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Label array where regions are marked by different integer values.
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color : length-3 sequence
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RGB color of boundaries in the output image.
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outline_color : length-3 sequence
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RGB color surrounding boundaries in the output image. If None, no
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outline is drawn.
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"""
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if image.ndim == 2:
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image = gray2rgb(image)
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image = img_as_float(image, force_copy=True)
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boundaries = find_boundaries(label_img)
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if outline_color is not None:
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outer_boundaries = dilation(boundaries.astype(np.uint8), square(3))
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image[outer_boundaries != 0, :] = np.array(outline_color)
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image[boundaries, :] = np.array(color)
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return image
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