Ma Nan
ce397b35aa
fix: contrast formulation cause leak of high value fix: empty series_id cause fail to read chore: restructure folder chore!: change layer vars BREAKING CHANGE: not support 4.1 any more
319 lines
11 KiB
Python
319 lines
11 KiB
Python
import warnings
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import numpy as np
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from .. import scipy as ndi
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from ._utils import convert_to_float
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def _clip_warp_output(input_image, output_image, mode, cval, clip):
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"""Clip output image to range of values of input image.
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Note that this function modifies the values of `output_image` in-place
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and it is only modified if ``clip=True``.
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Parameters
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----------
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input_image : ndarray
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Input image.
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output_image : ndarray
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Output image, which is modified in-place.
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Other parameters
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----------------
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mode : {'constant', 'edge', 'symmetric', 'reflect', 'wrap'}
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Points outside the boundaries of the input are filled according
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to the given mode. Modes match the behaviour of `numpy.pad`.
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cval : float
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Used in conjunction with mode 'constant', the value outside
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the image boundaries.
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clip : bool
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Whether to clip the output to the range of values of the input image.
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This is enabled by default, since higher order interpolation may
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produce values outside the given input range.
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"""
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if clip:
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min_val = np.min(input_image)
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if np.isnan(min_val):
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# NaNs detected, use NaN-safe min/max
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min_func = np.nanmin
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max_func = np.nanmax
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min_val = min_func(input_image)
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else:
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min_func = np.min
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max_func = np.max
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max_val = max_func(input_image)
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# Check if cval has been used such that it expands the effective input
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# range
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preserve_cval = (
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mode == 'constant'
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and not min_val <= cval <= max_val
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and min_func(output_image) <= cval <= max_func(output_image)
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)
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# expand min/max range to account for cval
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if preserve_cval:
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# cast cval to the same dtype as the input image
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cval = input_image.dtype.type(cval)
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min_val = min(min_val, cval)
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max_val = max(max_val, cval)
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# Convert array-like types to ndarrays (gh-7159)
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min_val, max_val = np.asarray(min_val), np.asarray(max_val)
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np.clip(output_image, min_val, max_val, out=output_image)
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def _validate_interpolation_order(image_dtype, order):
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"""Validate and return spline interpolation's order.
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Parameters
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----------
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image_dtype : dtype
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Image dtype.
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order : int, optional
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The order of the spline interpolation. The order has to be in
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the range 0-5. See `skimage.transform.warp` for detail.
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Returns
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-------
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order : int
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if input order is None, returns 0 if image_dtype is bool and 1
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otherwise. Otherwise, image_dtype is checked and input order
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is validated accordingly (order > 0 is not supported for bool
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image dtype)
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"""
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if order is None:
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return 0 if image_dtype == bool else 1
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if order < 0 or order > 5:
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raise ValueError(
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"Spline interpolation order has to be in the " "range 0-5.")
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if image_dtype == bool and order != 0:
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raise ValueError(
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"Input image dtype is bool. Interpolation is not defined "
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"with bool data type. Please set order to 0 or explicitly "
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"cast input image to another data type."
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)
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return order
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def _preprocess_resize_output_shape(image, output_shape):
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"""Validate resize output shape according to input image.
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Parameters
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----------
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image: ndarray
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Image to be resized.
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output_shape: iterable
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Size of the generated output image `(rows, cols[, ...][, dim])`. If
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`dim` is not provided, the number of channels is preserved.
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Returns
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-------
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image: ndarray
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The input image, but with additional singleton dimensions appended in
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the case where ``len(output_shape) > input.ndim``.
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output_shape: tuple
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The output image converted to tuple.
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Raises
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------
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ValueError:
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If output_shape length is smaller than the image number of
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dimensions
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Notes
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-----
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The input image is reshaped if its number of dimensions is not
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equal to output_shape_length.
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"""
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output_shape = tuple(output_shape)
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output_ndim = len(output_shape)
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input_shape = image.shape
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if output_ndim > image.ndim:
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# append dimensions to input_shape
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input_shape += (1,) * (output_ndim - image.ndim)
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image = np.reshape(image, input_shape)
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elif output_ndim == image.ndim - 1:
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# multichannel case: append shape of last axis
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output_shape = output_shape + (image.shape[-1],)
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elif output_ndim < image.ndim:
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raise ValueError(
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"output_shape length cannot be smaller than the "
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"image number of dimensions"
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)
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return image, output_shape
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def _to_ndimage_mode(mode):
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"""Convert from `numpy.pad` mode name to the corresponding ndimage mode."""
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mode_translation_dict = dict(
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constant='constant',
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edge='nearest',
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symmetric='reflect',
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reflect='mirror',
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wrap='wrap',
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)
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if mode not in mode_translation_dict:
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raise ValueError(
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f"Unknown mode: '{mode}', or cannot translate mode. The "
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f"mode should be one of 'constant', 'edge', 'symmetric', "
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f"'reflect', or 'wrap'. See the documentation of numpy.pad for "
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f"more info."
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)
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return _fix_ndimage_mode(mode_translation_dict[mode])
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def _fix_ndimage_mode(mode):
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# SciPy 1.6.0 introduced grid variants of constant and wrap which
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# have less surprising behavior for images. Use these when available
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grid_modes = {'constant': 'grid-constant', 'wrap': 'grid-wrap'}
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return grid_modes.get(mode, mode)
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def resize(
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image,
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output_shape,
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order=None,
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mode='reflect',
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cval=0,
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clip=True,
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preserve_range=False,
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anti_aliasing=None,
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anti_aliasing_sigma=None,
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):
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"""Resize image to match a certain size.
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Performs interpolation to up-size or down-size N-dimensional images. Note
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that anti-aliasing should be enabled when down-sizing images to avoid
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aliasing artifacts. For downsampling with an integer factor also see
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`skimage.transform.downscale_local_mean`.
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Parameters
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----------
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image : ndarray
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Input image.
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output_shape : iterable
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Size of the generated output image `(rows, cols[, ...][, dim])`. If
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`dim` is not provided, the number of channels is preserved. In case the
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number of input channels does not equal the number of output channels a
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n-dimensional interpolation is applied.
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Returns
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-------
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resized : ndarray
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Resized version of the input.
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Other parameters
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----------------
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order : int, optional
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The order of the spline interpolation, default is 0 if
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image.dtype is bool and 1 otherwise. The order has to be in
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the range 0-5. See `skimage.transform.warp` for detail.
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mode : {'constant', 'edge', 'symmetric', 'reflect', 'wrap'}, optional
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Points outside the boundaries of the input are filled according
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to the given mode. Modes match the behaviour of `numpy.pad`.
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cval : float, optional
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Used in conjunction with mode 'constant', the value outside
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the image boundaries.
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clip : bool, optional
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Whether to clip the output to the range of values of the input image.
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This is enabled by default, since higher order interpolation may
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produce values outside the given input range.
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preserve_range : bool, optional
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Whether to keep the original range of values. Otherwise, the input
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image is converted according to the conventions of `img_as_float`.
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Also see https://scikit-image.org/docs/dev/user_guide/data_types.html
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anti_aliasing : bool, optional
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Whether to apply a Gaussian filter to smooth the image prior
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to downsampling. It is crucial to filter when downsampling
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the image to avoid aliasing artifacts. If not specified, it is set to
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True when downsampling an image whose data type is not bool.
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It is also set to False when using nearest neighbor interpolation
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(``order`` == 0) with integer input data type.
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anti_aliasing_sigma : {float, tuple of floats}, optional
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Standard deviation for Gaussian filtering used when anti-aliasing.
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By default, this value is chosen as (s - 1) / 2 where s is the
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downsampling factor, where s > 1. For the up-size case, s < 1, no
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anti-aliasing is performed prior to rescaling.
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Notes
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-----
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Modes 'reflect' and 'symmetric' are similar, but differ in whether the edge
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pixels are duplicated during the reflection. As an example, if an array
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has values [0, 1, 2] and was padded to the right by four values using
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symmetric, the result would be [0, 1, 2, 2, 1, 0, 0], while for reflect it
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would be [0, 1, 2, 1, 0, 1, 2].
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Examples
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--------
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>>> from skimage import data
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>>> from skimage.transform import resize
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>>> image = data.camera()
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>>> resize(image, (100, 100)).shape
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(100, 100)
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"""
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image, output_shape = _preprocess_resize_output_shape(image, output_shape)
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input_shape = image.shape
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input_type = image.dtype
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if input_type == np.float16:
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image = image.astype(np.float32)
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if anti_aliasing is None:
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anti_aliasing = (
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not input_type == bool
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and not (np.issubdtype(input_type, np.integer) and order == 0)
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and any(x < y for x, y in zip(output_shape, input_shape))
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)
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if input_type == bool and anti_aliasing:
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raise ValueError("anti_aliasing must be False for boolean images")
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factors = np.divide(input_shape, output_shape)
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order = _validate_interpolation_order(input_type, order)
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if order > 0:
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image = convert_to_float(image, preserve_range)
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# Translate modes used by np.pad to those used by scipy.ndimage
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ndi_mode = _to_ndimage_mode(mode)
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if anti_aliasing:
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if anti_aliasing_sigma is None:
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anti_aliasing_sigma = np.maximum(0, (factors - 1) / 2)
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else:
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anti_aliasing_sigma = np.atleast_1d(anti_aliasing_sigma) * np.ones_like(
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factors
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)
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if np.any(anti_aliasing_sigma < 0):
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raise ValueError(
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"Anti-aliasing standard deviation must be "
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"greater than or equal to zero"
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)
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elif np.any((anti_aliasing_sigma > 0) & (factors <= 1)):
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warnings.warn(
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"Anti-aliasing standard deviation greater than zero but "
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"not down-sampling along all axes",
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stacklevel=2
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)
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filtered = ndi.gaussian_filter(
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image, anti_aliasing_sigma, cval=cval, mode=ndi_mode
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)
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else:
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filtered = image
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zoom_factors = [1 / f for f in factors]
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out = ndi.zoom(
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filtered, zoom_factors, order=order, mode=ndi_mode, cval=cval, grid_mode=True
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)
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_clip_warp_output(image, out, mode, cval, clip)
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return out
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