mirror of
https://github.com/wassname/scikit-image.git
synced 2026-06-29 12:24:45 +08:00
Stefan van der Walt
81 lines
2.5 KiB
Python
81 lines
2.5 KiB
Python
import numpy as np
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#from scipy.ndimage import label
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from ..measure import label
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def clear_border(labels, buffer_size=0, bgval=0, in_place=False):
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"""Clear objects connected to the label image border.
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The changes will be applied directly to the input.
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Parameters
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----------
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labels : (N, M) array of int
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Label or binary image.
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buffer_size : int, optional
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The width of the border examined. By default, only objects
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that touch the outside of the image are removed.
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bgval : float or int, optional
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Cleared objects are set to this value.
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in_place : bool, optional
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Whether or not to manipulate the labels array in-place.
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Returns
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-------
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labels : (N, M) array
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Cleared binary image.
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Examples
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--------
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>>> import numpy as np
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>>> from skimage.segmentation import clear_border
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>>> labels = np.array([[0, 0, 0, 0, 0, 0, 0, 1, 0],
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... [0, 0, 0, 0, 1, 0, 0, 0, 0],
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... [1, 0, 0, 1, 0, 1, 0, 0, 0],
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... [0, 0, 1, 1, 1, 1, 1, 0, 0],
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... [0, 1, 1, 1, 1, 1, 1, 1, 0],
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... [0, 0, 0, 0, 0, 0, 0, 0, 0]])
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>>> clear_border(labels)
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array([[0, 0, 0, 0, 0, 0, 0, 0, 0],
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[0, 0, 0, 0, 1, 0, 0, 0, 0],
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[0, 0, 0, 1, 0, 1, 0, 0, 0],
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[0, 0, 1, 1, 1, 1, 1, 0, 0],
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[0, 1, 1, 1, 1, 1, 1, 1, 0],
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[0, 0, 0, 0, 0, 0, 0, 0, 0]])
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"""
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image = labels
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rows, cols = image.shape
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if buffer_size >= rows or buffer_size >= cols:
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raise ValueError("buffer size may not be greater than image size")
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# create borders with buffer_size
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borders = np.zeros_like(image, dtype=np.bool_)
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ext = buffer_size + 1
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borders[:ext] = True
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borders[- ext:] = True
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borders[:, :ext] = True
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borders[:, - ext:] = True
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# Re-label, in case we are dealing with a binary image
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# and to get consistent labeling
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labels = label(image, background=0) + 1
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number = np.max(labels) + 1
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# determine all objects that are connected to borders
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borders_indices = np.unique(labels[borders])
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indices = np.arange(number + 1)
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# mask all label indices that are connected to borders
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label_mask = np.in1d(indices, borders_indices)
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# create mask for pixels to clear
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mask = label_mask[labels.ravel()].reshape(labels.shape)
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if not in_place:
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image = image.copy()
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# clear border pixels
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image[mask] = bgval
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return image
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