mirror of
https://github.com/wassname/scikit-image.git
synced 2026-07-06 05:16:40 +08:00
Ankit Agrawal
61 lines
1.7 KiB
Python
61 lines
1.7 KiB
Python
# TODO : Doc, Tests, PEP8 check
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import numpy as np
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from skimage.util.shape import view_as_blocks
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def _pad_asymmetric_zeros(arr, pad_amt, axis=-1):
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"""Pads `arr` by `pad_amt` along specified `axis`"""
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if axis == -1:
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axis = arr.ndim - 1
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zeroshape = tuple([x if i != axis else pad_amt
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for (i, x) in enumerate(arr.shape)])
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return np.concatenate((arr, np.zeros(zeroshape, dtype=arr.dtype)),
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axis=axis)
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def downsample(image, factors, method='sum'):
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pad_size = []
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if len(factors) != image.ndim:
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raise ValueError("'factors' must have the same length "
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"as 'image.shape'")
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else:
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for i in range(len(factors)):
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if image.shape[i] % factors[i] != 0:
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pad_size.append(factors[i] - (image.shape[i] % factors[i]))
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else:
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pad_size.append(0)
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for i in range(len(pad_size)):
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image = _pad_asymmetric_zeros(image, pad_size[i], i)
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out = view_as_blocks(image, factors)
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block_shape = out.shape
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if method == 'sum':
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for i in range(len(block_shape)/2):
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out = out.sum(-1)
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else:
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for i in range(len(block_shape)/2):
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out = out.mean(-1)
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return out
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def upsample(image, factors, method='divide'):
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f = factors
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if (f[0] - int(f[0]) != 0) or (f[1] - int(f[1]) != 0):
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raise ValueError('Use resample() for non-integer upsampling')
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out = np.zeros((f[0] * image.shape[0], f[1] * image.shape[1]))
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for i in range(out.shape[0]):
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for j in range(out.shape[1]):
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out[i][j] = (image[i / f[0]][j / f[1]])
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if method == 'divide':
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return out / float(f[0] * f[1])
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else:
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return out
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