42 lines
1.1 KiB
Python
42 lines
1.1 KiB
Python
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import numpy as np
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from . import draw
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def polygon2mask(image_shape, polygon):
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"""Compute a mask from polygon.
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Parameters
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----------
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image_shape : tuple of size 2.
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The shape of the mask.
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polygon : array_like.
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The polygon coordinates of shape (N, 2) where N is
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the number of points.
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Returns
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-------
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mask : 2-D ndarray of type 'bool'.
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The mask that corresponds to the input polygon.
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Notes
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-----
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This function does not do any border checking, so that all
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the vertices need to be within the given shape.
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Examples
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--------
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>>> image_shape = (128, 128)
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>>> polygon = np.array([[60, 100], [100, 40], [40, 40]])
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>>> mask = polygon2mask(image_shape, polygon)
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>>> mask.shape
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(128, 128)
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"""
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polygon = np.asarray(polygon)
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vertex_row_coords, vertex_col_coords = polygon.T
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fill_row_coords, fill_col_coords = draw.polygon(
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vertex_row_coords, vertex_col_coords, image_shape)
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mask = np.zeros(image_shape, dtype=np.bool)
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mask[fill_row_coords, fill_col_coords] = True
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return mask
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