75 lines
2.5 KiB
Python
75 lines
2.5 KiB
Python
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import numpy as np
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import scipy.ndimage as ndi
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from ..util import img_as_float
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from ..color import rgb2lab
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from ._quickshift_cy import _quickshift_cython
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def quickshift(image, ratio=1.0, kernel_size=5, max_dist=10,
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return_tree=False, sigma=0, convert2lab=True, random_seed=42):
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"""Segments image using quickshift clustering in Color-(x,y) space.
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Produces an oversegmentation of the image using the quickshift mode-seeking
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algorithm.
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Parameters
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----------
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image : (width, height, channels) ndarray
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Input image.
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ratio : float, optional, between 0 and 1
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Balances color-space proximity and image-space proximity.
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Higher values give more weight to color-space.
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kernel_size : float, optional
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Width of Gaussian kernel used in smoothing the
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sample density. Higher means fewer clusters.
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max_dist : float, optional
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Cut-off point for data distances.
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Higher means fewer clusters.
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return_tree : bool, optional
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Whether to return the full segmentation hierarchy tree and distances.
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sigma : float, optional
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Width for Gaussian smoothing as preprocessing. Zero means no smoothing.
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convert2lab : bool, optional
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Whether the input should be converted to Lab colorspace prior to
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segmentation. For this purpose, the input is assumed to be RGB.
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random_seed : int, optional
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Random seed used for breaking ties.
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Returns
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-------
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segment_mask : (width, height) ndarray
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Integer mask indicating segment labels.
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Notes
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-----
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The authors advocate to convert the image to Lab color space prior to
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segmentation, though this is not strictly necessary. For this to work, the
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image must be given in RGB format.
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References
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----------
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.. [1] Quick shift and kernel methods for mode seeking,
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Vedaldi, A. and Soatto, S.
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European Conference on Computer Vision, 2008
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"""
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image = img_as_float(np.atleast_3d(image))
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if convert2lab:
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if image.shape[2] != 3:
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ValueError("Only RGB images can be converted to Lab space.")
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image = rgb2lab(image)
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if kernel_size < 1:
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raise ValueError("`kernel_size` should be >= 1.")
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image = ndi.gaussian_filter(image, [sigma, sigma, 0])
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image = np.ascontiguousarray(image * ratio)
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segment_mask = _quickshift_cython(
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image, kernel_size=kernel_size, max_dist=max_dist,
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return_tree=return_tree, random_seed=random_seed)
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return segment_mask
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