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import copy |
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from collections import defaultdict |
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from typing import Tuple, Optional, Union, List, Dict, Sequence |
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import torch |
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from ....torchio import DATA |
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from ....utils import get_random_seed |
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from ....data.subject import Subject |
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from ... import IntensityTransform |
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from .. import RandomTransform |
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class RandomNoise(RandomTransform, IntensityTransform): |
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r"""Add Gaussian noise with random parameters. |
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Add noise sampled from a normal distribution with random parameters. |
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Args: |
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mean: Mean :math:`\mu` of the Gaussian distribution |
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from which the noise is sampled. |
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If two values :math:`(a, b)` are provided, |
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then :math:`\mu \sim \mathcal{U}(a, b)`. |
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If only one value :math:`d` is provided, |
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:math:`\mu \sim \mathcal{U}(-d, d)`. |
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std: Standard deviation :math:`\sigma` of the Gaussian distribution |
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from which the noise is sampled. |
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If two values :math:`(a, b)` are provided, |
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then :math:`\sigma \sim \mathcal{U}(a, b)`. |
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If only one value :math:`d` is provided, |
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:math:`\sigma \sim \mathcal{U}(0, d)`. |
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p: Probability that this transform will be applied. |
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seed: See :py:class:`~torchio.transforms.augmentation.RandomTransform`. |
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keys: See :py:class:`~torchio.transforms.Transform`. |
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""" |
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def __init__( |
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self, |
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mean: Union[float, Tuple[float, float]] = 0, |
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std: Union[float, Tuple[float, float]] = (0, 0.25), |
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p: float = 1, |
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keys: Optional[Sequence[str]] = None, |
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): |
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super().__init__(p=p, keys=keys) |
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self.mean_range = self.parse_range(mean, 'mean') |
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self.std_range = self.parse_range(std, 'std', min_constraint=0) |
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def apply_transform(self, subject: Subject) -> Subject: |
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arguments = defaultdict(dict) |
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for image_name in self.get_images_dict(subject): |
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mean, std, seed = self.get_params(self.mean_range, self.std_range) |
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arguments['mean'][image_name] = mean |
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arguments['std'][image_name] = std |
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arguments['seed'][image_name] = seed |
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transform = Noise(**arguments) |
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transformed = transform(subject) |
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return transformed |
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@staticmethod |
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def get_params( |
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mean_range: Tuple[float, float], |
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std_range: Tuple[float, float], |
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) -> Tuple[float, float]: |
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mean = torch.FloatTensor(1).uniform_(*mean_range).item() |
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std = torch.FloatTensor(1).uniform_(*std_range).item() |
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seed = get_random_seed() |
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return mean, std, seed |
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class Noise(IntensityTransform): |
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r"""Add Gaussian noise. |
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Add noise sampled from a normal distribution. |
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Args: |
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mean: Mean :math:`\mu` of the Gaussian distribution |
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from which the noise is sampled. |
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std: Standard deviation :math:`\sigma` of the Gaussian distribution |
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from which the noise is sampled. |
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seed: |
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keys: See :py:class:`~torchio.transforms.Transform`. |
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""" |
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def __init__( |
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self, |
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mean: Union[float, Dict[str, float]], |
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std: Union[float, Dict[str, float]], |
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seed: Union[int, Sequence[int]], |
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keys: Optional[List[str]] = None, |
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): |
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super().__init__(keys=keys) |
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self.mean = mean |
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self.std = std |
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self.seed = seed |
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self._has_dicts = self.parse_arguments() |
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self.invert_transform = False |
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def get_arguments(self): |
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return {'mean': self.mean, 'std': self.std, 'seed': self.seed} |
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def parse_arguments(self): |
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mean_dict = isinstance(self.mean, dict) |
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std_dict = isinstance(self.std, dict) |
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seed_dict = isinstance(self.seed, dict) |
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three_bools = mean_dict, std_dict, seed_dict |
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if all(three_bools): |
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return True |
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elif not any(three_bools): |
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return False |
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else: |
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message = 'All arguments must have the same type: float or dict' |
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raise ValueError(message) |
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def apply_transform(self, subject: Subject) -> Subject: |
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args = self.mean, self.std, self.seed |
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for name, image in self.get_images_dict(subject).items(): |
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if self._has_dicts: |
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args = self.mean[name], self.std[name], self.seed[name] |
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noise = get_noise(image[DATA], *args) |
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if self.invert_transform: |
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noise *= -1 |
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image[DATA] = image[DATA] + noise |
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return subject |
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def inverse(self): |
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new = copy.deepcopy(self) |
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new.invert_transform = not self.invert_transform |
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return new |
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def get_randn(shape: Sequence[int], seed: int) -> torch.Tensor: |
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torch_rng_state = torch.random.get_rng_state() |
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torch.manual_seed(seed) |
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noise = torch.randn(*shape) |
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torch.random.set_rng_state(torch_rng_state) |
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return noise |
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def get_noise( |
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tensor: torch.Tensor, |
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mean: float, |
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std: float, |
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seed: Optional[int] = None) -> torch.Tensor: |
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return get_randn(tensor.shape, seed=seed) * std + mean |
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fepegar /
torchio
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