video_transforms.py

"""
This file is obtained and modified from:
- https://github.com/piergiaj/pytorch-i3d
- https://github.com/jbohnslav/opencv_transforms
- https://github.com/YU-Zhiyang/opencv_transforms_torchvision
- https://pytorch.org/docs/stable/_modules/torchvision/transforms/transforms.html
"""
import os
thread = "1"
os.environ["MKL_NUM_THREADS"] = thread
os.environ["NUMEXPR_NUM_THREADS"] = thread
os.environ["OMP_NUM_THREADS"] = thread
os.environ["VECLIB_MAXIMUM_THREADS"] = thread
os.environ["OPENBLAS_NUM_THREADS"] = thread
import cv2
cv2.setNumThreads(0)

import numpy as np
import numbers
import random
import warnings
import types
import opencv_functional as F
import torchvision.transforms.functional as FF
from torchvision.transforms import Compose
import math
import torch


class RandomCrop(object):
    """Crop the given video sequences (t x h x w) at a random location.
    Args:
        size (sequence or int): Desired output size of the crop. If size is an
            int instead of sequence like (h, w), a square crop (size, size) is
            made.
    """
    def __init__(self, size):
        if isinstance(size, numbers.Number):
            self.size = (int(size), int(size))
        else:
            self.size = size

    @staticmethod
    def get_params(img, output_size):
        """Get parameters for ``crop`` for a random crop.
        Args:
            img (PIL Image): Image to be cropped.
            output_size (tuple): Expected output size of the crop.
        Returns:
            tuple: params (i, j, h, w) to be passed to ``crop`` for random crop.
        """
        t, h, w, c = img.shape
        th, tw = output_size
        if w == tw and h == th:
            return 0, 0, h, w

        i = random.randint(0, h - th) if h!=th else 0
        j = random.randint(0, w - tw) if w!=tw else 0
        return i, j, th, tw

    def __call__(self, imgs):

        i, j, h, w = self.get_params(imgs, self.size)

        imgs = imgs[:, i:i+h, j:j+w, :]
        return imgs

    def __repr__(self):
        return self.__class__.__name__ + '(size={0})'.format(self.size)


class CenterCrop(object):
    """Crops the given seq Images at the center.
    Args:
        size (sequence or int): Desired output size of the crop. If size is an
            int instead of sequence like (h, w), a square crop (size, size) is
            made.
    """
    def __init__(self, size):
        if isinstance(size, numbers.Number):
            self.size = (int(size), int(size))
        else:
            self.size = size

    def __call__(self, imgs):
        """
        Args:
            img (PIL Image): Image to be cropped.
        Returns:
            PIL Image: Cropped image.
        """
        t, h, w, c = imgs.shape
        th, tw = self.size
        i = int(np.round((h - th) / 2.))
        j = int(np.round((w - tw) / 2.))

        return imgs[:, i:i+th, j:j+tw, :]

    def __repr__(self):
        return self.__class__.__name__ + '(size={0})'.format(self.size)


class RandomHorizontalFlip(object):
    """Horizontally flip the given seq Images randomly with a given probability.
    Args:
        p (float): probability of the image being flipped. Default value is 0.5
    """
    def __init__(self, p=0.5):
        self.p = p

    def __call__(self, imgs):
        """
        Args:
            img (seq Images): seq Images to be flipped.
        Returns:
            seq Images: Randomly flipped seq images.
        """
        if random.random() < self.p:
            # t x h x w
            return np.flip(imgs, axis=2).copy()
        return imgs

    def __repr__(self):
        return self.__class__.__name__ + '(p={})'.format(self.p)


class Lambda(object):
    """Apply a user-defined lambda as a transform.
    Args:
        lambd (function): Lambda/function to be used for transform.
    """
    def __init__(self, lambd):
        assert isinstance(lambd, types.LambdaType)
        self.lambd = lambd

    def __call__(self, img):
        return self.lambd(img)

    def __repr__(self):
        return self.__class__.__name__ + '()'


class ColorJitter(object):
    """Randomly change the brightness, contrast and saturation of a sequence of images.
    Args:
        brightness (float or tuple of float (min, max)): How much to jitter brightness.
            brightness_factor is chosen uniformly from [max(0, 1 - brightness), 1 + brightness]
            or the given [min, max]. Should be non negative numbers.
        contrast (float or tuple of float (min, max)): How much to jitter contrast.
            contrast_factor is chosen uniformly from [max(0, 1 - contrast), 1 + contrast]
            or the given [min, max]. Should be non negative numbers.
        saturation (float or tuple of float (min, max)): How much to jitter saturation.
            saturation_factor is chosen uniformly from [max(0, 1 - saturation), 1 + saturation]
            or the given [min, max]. Should be non negative numbers.
        hue (float or tuple of float (min, max)): How much to jitter hue.
            hue_factor is chosen uniformly from [-hue, hue] or the given [min, max].
            Should have 0<= hue <= 0.5 or -0.5 <= min <= max <= 0.5.
        gamma (float or tuple of float (min, max)): How much to jitter gamma.
            gamma_factor is chosen uniformly from [max(0, 1 - gamma), 1 + gamma]
    """
    def __init__(self, brightness=0, contrast=0, saturation=0, hue=0, gamma=0):
        self.brightness = self._check_input(brightness, 'brightness')
        self.contrast = self._check_input(contrast, 'contrast')
        self.saturation = self._check_input(saturation, 'saturation')
        self.hue = self._check_input(hue, 'hue', center=0, bound=(-0.5, 0.5),
                                     clip_first_on_zero=False)
        self.gamma = self._check_input(gamma, 'gamma')

        if self.saturation is not None:
            warnings.warn('Saturation jitter enabled. Will slow down loading immensely.')
        if self.hue is not None:
            warnings.warn('Hue jitter enabled. Will slow down loading immensely.')

    def _check_input(self, value, name, center=1, bound=(0, float('inf')), clip_first_on_zero=True):
        if isinstance(value, numbers.Number):
            if value < 0:
                raise ValueError("If {} is a single number, it must be non negative.".format(name))
            value = [center - value, center + value]
            if clip_first_on_zero:
                value[0] = max(value[0], 0)
        elif isinstance(value, (tuple, list)) and len(value) == 2:
            if not bound[0] <= value[0] <= value[1] <= bound[1]:
                raise ValueError("{} values should be between {}".format(name, bound))
        else:
            raise TypeError("{} should be a single number or a list/tuple with length 2.".format(name))

        # if value is 0 or (1., 1.) for brightness/contrast/saturation/gamma
        # or (0., 0.) for hue, do nothing
        if value[0] == value[1] == center:
            value = None
        return value

    @staticmethod
    def get_params(brightness, contrast, saturation, hue, gamma):
        """Get a randomized transform to be applied on image.
        Arguments are same as that of __init__.
        Returns:
            Transform which randomly adjusts brightness, contrast and
            saturation in a random order.
        """
        transforms = []

        if brightness is not None:
            brightness_factor = random.uniform(brightness[0], brightness[1])
            transforms.append(Lambda(lambda img: F.adjust_brightness(img, brightness_factor)))

        if contrast is not None:
            contrast_factor = random.uniform(contrast[0], contrast[1])
            transforms.append(Lambda(lambda img: F.adjust_contrast(img, contrast_factor)))

        if saturation is not None:
            saturation_factor = random.uniform(saturation[0], saturation[1])
            transforms.append(Lambda(lambda img: F.adjust_saturation(img, saturation_factor)))

        if hue is not None:
            hue_factor = random.uniform(hue[0], hue[1])
            transforms.append(Lambda(lambda img: F.adjust_hue(img, hue_factor)))

        if gamma is not None:
            gamma_factor = random.uniform(gamma[0], gamma[1])
            transforms.append(Lambda(lambda img: F.adjust_gamma(img, gamma_factor)))

        random.shuffle(transforms)
        transform = Compose(transforms)

        return transform

    def __call__(self, imgs):
        """
        Args:
            imgs (numpy ndarray): Input image sequence (time*height*width*channel).
        Returns:
            numpy ndarray: Color jittered image sequence.
        """
        transform = self.get_params(self.brightness, self.contrast,
                                    self.saturation, self.hue, self.gamma)
        # Apply to all images
        output_imgs = []
        for I in imgs:
            output_imgs.append(transform(I))
        return np.array(output_imgs)

    def __repr__(self):
        format_string = self.__class__.__name__ + '('
        format_string += 'brightness={0}'.format(self.brightness)
        format_string += ', contrast={0}'.format(self.contrast)
        format_string += ', saturation={0}'.format(self.saturation)
        format_string += ', hue={0})'.format(self.hue)
        format_string += ', gamma={0})'.format(self.gamma)
        return format_string


class RandomResizedCrop(object):
    """Crop the given numpy ndarray image sequence to random size and aspect ratio.
    A crop of random size (default: of 0.08 to 1.0) of the original size and a random
    aspect ratio (default: of 3/4 to 4/3) of the original aspect ratio is made. This crop
    is finally resized to given size.
    This is popularly used to train the Inception networks.
    Args:
        size: expected output size of each edge
        scale: range of size of the origin size cropped
        ratio: range of aspect ratio of the origin aspect ratio cropped
        interpolation: Default: cv2.INTER_CUBIC
    """
    def __init__(self, size, scale=(0.08, 1.0), ratio=(3. / 4., 4. / 3.), interpolation=cv2.INTER_CUBIC):
        self.size = (size, size)
        self.interpolation = interpolation
        self.scale = scale
        self.ratio = ratio

    @staticmethod
    def get_params(img, scale, ratio):
        """Get parameters for ``crop`` for a random sized crop.
        Args:
            img (numpy ndarray): Image to be cropped.
            scale (tuple): range of size of the origin size cropped
            ratio (tuple): range of aspect ratio of the origin aspect ratio cropped
        Returns:
            tuple: params (i, j, h, w) to be passed to ``crop`` for a random
                sized crop.
        """
        for attempt in range(10):
            area = img.shape[0] * img.shape[1]
            target_area = random.uniform(*scale) * area
            aspect_ratio = random.uniform(*ratio)

            w = int(round(math.sqrt(target_area * aspect_ratio)))
            h = int(round(math.sqrt(target_area / aspect_ratio)))

            if random.random() < 0.5:
                w, h = h, w

            if w <= img.shape[1] and h <= img.shape[0]:
                i = random.randint(0, img.shape[0] - h)
                j = random.randint(0, img.shape[1] - w)
                return i, j, h, w

        # Fallback
        w = min(img.shape[0], img.shape[1])
        i = (img.shape[0] - w) // 2
        j = (img.shape[1] - w) // 2
        return i, j, w, w

    def __call__(self, imgs):
        """
        Args:
            imgs (numpy ndarray): Image sequence (time*height*width*channel) to be cropped and resized.
        Returns:
            numpy ndarray: Randomly cropped and resized image sequence.
        """
        i, j, h, w = self.get_params(imgs[0, ...], self.scale, self.ratio)
        # Apply to all images
        output_imgs = []
        for I in imgs:
            output_imgs.append(F.resized_crop(I, i, j, h, w, self.size, self.interpolation))
        return np.array(output_imgs)

    def __repr__(self):
        interpolate_str = _pil_interpolation_to_str[self.interpolation]
        format_string = self.__class__.__name__ + '(size={0}'.format(self.size)
        format_string += ', scale={0}'.format(tuple(round(s, 4) for s in self.scale))
        format_string += ', ratio={0}'.format(tuple(round(r, 4) for r in self.ratio))
        format_string += ', interpolation={0})'.format(interpolate_str)
        return format_string


class RandomRotation(object):
    """Rotate the image sequence by angle.
    Args:
        degrees (sequence or float or int): Range of degrees to select from.
            If degrees is a number instead of sequence like (min, max), the range of degrees
            will be (-degrees, +degrees).
        resample ({cv2.INTER_NEAREST, cv2.INTER_LINEAR, cv2.INTER_CUBIC, cv2.INTER_LANCZOS4}, optional):
            An optional resampling filter. See `filters`_ for more information.
            If omitted, or if the image has mode "1" or "P", it is set to PIL.Image.NEAREST.
        expand (bool, optional): Optional expansion flag.
            If true, expands the output to make it large enough to hold the entire rotated image.
            If false or omitted, make the output image the same size as the input image.
            Note that the expand flag assumes rotation around the center and no translation.
        center (2-tuple, optional): Optional center of rotation.
            Origin is the upper left corner.
            Default is the center of the image.
    """
    def __init__(self, degrees, resample=False, expand=False, center=None):
        if isinstance(degrees, numbers.Number):
            if degrees < 0:
                raise ValueError("If degrees is a single number, it must be positive.")
            self.degrees = (-degrees, degrees)
        else:
            if len(degrees) != 2:
                raise ValueError("If degrees is a sequence, it must be of len 2.")
            self.degrees = degrees

        self.resample = resample
        self.expand = expand
        self.center = center

    @staticmethod
    def get_params(degrees):
        """Get parameters for ``rotate`` for a random rotation.
        Returns:
            sequence: params to be passed to ``rotate`` for random rotation.
        """
        angle = random.uniform(degrees[0], degrees[1])

        return angle

    def __call__(self, imgs):
        """
            imgs (numpy ndarray): Image sequence (time*height*width*channel) to be rotated.
        Returns:
            numpy ndarray: Rotated image sequence.
        """
        angle = self.get_params(self.degrees)
        # Apply to all images
        output_imgs = []
        for I in imgs:
            output_imgs.append(F.rotate(I, angle, self.resample, self.expand, self.center))
        return np.array(output_imgs)

    def __repr__(self):
        format_string = self.__class__.__name__ + '(degrees={0}'.format(self.degrees)
        format_string += ', resample={0}'.format(self.resample)
        format_string += ', expand={0}'.format(self.expand)
        if self.center is not None:
            format_string += ', center={0}'.format(self.center)
        format_string += ')'
        return format_string


class RandomAffine(object):
    """Random affine transformation of the image sequence keeping center invariant
    Args:
        degrees (sequence or float or int): Range of degrees to select from.
            If degrees is a number instead of sequence like (min, max), the range of degrees
            will be (-degrees, +degrees). Set to 0 to deactivate rotations.
        translate (tuple, optional): tuple of maximum absolute fraction for horizontal
            and vertical translations. For example translate=(a, b), then horizontal shift
            is randomly sampled in the range -img_width * a < dx < img_width * a and vertical shift is
            randomly sampled in the range -img_height * b < dy < img_height * b. Will not translate by default.
        scale (tuple, optional): scaling factor interval, e.g (a, b), then scale is
            randomly sampled from the range a <= scale <= b. Will keep original scale by default.
        shear (sequence or float or int, optional): Range of degrees to select from.
            If degrees is a number instead of sequence like (min, max), the range of degrees
            will be (-degrees, +degrees). Will not apply shear by default
        resample ({cv2.INTER_NEAREST, cv2.INTER_LINEAR, cv2.INTER_CUBIC, cv2.INTER_LANCZOS4}, optional):
            An optional resampling filter. See `filters`_ for more information.
            If omitted, or if the image has mode "1" or "P", it is set to PIL.Image.NEAREST.
        fillcolor (int): Optional fill color for the area outside the transform in the output image.
    """
    def __init__(self, degrees, translate=None, scale=None, shear=None, interpolation=cv2.INTER_CUBIC, fillcolor=0):
        if isinstance(degrees, numbers.Number):
            if degrees < 0:
                raise ValueError("If degrees is a single number, it must be positive.")
            self.degrees = (-degrees, degrees)
        else:
            assert isinstance(degrees, (tuple, list)) and len(degrees) == 2, \
                "degrees should be a list or tuple and it must be of length 2."
            self.degrees = degrees

        if translate is not None:
            assert isinstance(translate, (tuple, list)) and len(translate) == 2, \
                "translate should be a list or tuple and it must be of length 2."
            for t in translate:
                if not (0.0 <= t <= 1.0):
                    raise ValueError("translation values should be between 0 and 1")
        self.translate = translate

        if scale is not None:
            assert isinstance(scale, (tuple, list)) and len(scale) == 2, \
                "scale should be a list or tuple and it must be of length 2."
            for s in scale:
                if s <= 0:
                    raise ValueError("scale values should be positive")
        self.scale = scale

        if shear is not None:
            if isinstance(shear, numbers.Number):
                if shear < 0:
                    raise ValueError("If shear is a single number, it must be positive.")
                self.shear = (-shear, shear)
            else:
                assert isinstance(shear, (tuple, list)) and len(shear) == 2, \
                    "shear should be a list or tuple and it must be of length 2."
                self.shear = shear
        else:
            self.shear = shear

        # self.resample = resample
        self.interpolation = interpolation
        self.fillcolor = fillcolor

    @staticmethod
    def get_params(degrees, translate, scale_ranges, shears, img_size):
        """Get parameters for affine transformation
        Returns:
            sequence: params to be passed to the affine transformation
        """
        angle = random.uniform(degrees[0], degrees[1])
        if translate is not None:
            max_dx = translate[0] * img_size[0]
            max_dy = translate[1] * img_size[1]
            translations = (np.round(random.uniform(-max_dx, max_dx)),
                            np.round(random.uniform(-max_dy, max_dy)))
        else:
            translations = (0, 0)

        if scale_ranges is not None:
            scale = random.uniform(scale_ranges[0], scale_ranges[1])
        else:
            scale = 1.0

        if shears is not None:
            shear = random.uniform(shears[0], shears[1])
        else:
            shear = 0.0

        return angle, translations, scale, shear

    def __call__(self, imgs):
        """
            imgs (numpy ndarray): Image sequence (time*height*width*channel) to be transformed.
        Returns:
            numpy ndarray: Affine transformed image sequence.
        """
        ret = self.get_params(self.degrees, self.translate, self.scale, self.shear, (imgs.shape[2], imgs.shape[1]))
        # Apply to all images
        output_imgs = []
        for I in imgs:
            output_imgs.append(F.affine(I, *ret, interpolation=self.interpolation, fillcolor=self.fillcolor))
        return np.array(output_imgs)

    def __repr__(self):
        s = '{name}(degrees={degrees}'
        if self.translate is not None:
            s += ', translate={translate}'
        if self.scale is not None:
            s += ', scale={scale}'
        if self.shear is not None:
            s += ', shear={shear}'
        if self.resample > 0:
            s += ', resample={resample}'
        if self.fillcolor != 0:
            s += ', fillcolor={fillcolor}'
        s += ')'
        d = dict(self.__dict__)
        d['resample'] = _pil_interpolation_to_str[d['resample']]
        return s.format(name=self.__class__.__name__, **d)


class RandomPerspective(object):
    """Random perspective transformation of the image sequence keeping center invariant
    Args:
        fov(float): range of wide angle = 90+-fov
        anglex (sequence or float or int): Range of degrees rote around X axis to select from.
            If degrees is a number instead of sequence like (min, max), the range of degrees
            will be (-degrees, +degrees). Set to 0 to desactivate rotations.
        angley (sequence or float or int): Range of degrees rote around Y axis to select from.
            If degrees is a number instead of sequence like (min, max), the range of degrees
            will be (-degrees, +degrees). Set to 0 to desactivate rotations.
        anglez (sequence or float or int): Range of degrees rote around Z axis to select from.
            If degrees is a number instead of sequence like (min, max), the range of degrees
            will be (-degrees, +degrees). Set to 0 to desactivate rotations.
        shear (sequence or float or int): Range of degrees for shear rote around axis to select from.
            If degrees is a number instead of sequence like (min, max), the range of degrees
            will be (-degrees, +degrees). Set to 0 to desactivate rotations.
        translate (tuple, optional): tuple of maximum absolute fraction for horizontal
            and vertical translations. For example translate=(a, b), then horizontal shift
            is randomly sampled in the range -img_width * a < dx < img_width * a and vertical shift is
            randomly sampled in the range -img_height * b < dy < img_height * b. Will not translate by default.
        scale (tuple, optional): scaling factor interval, e.g (a, b), then scale is
            randomly sampled from the range a <= scale <= b. Will keep original scale by default.
        resample ({nearest, bilinear, bicubic}, optional): An optional resampling filter.
        fillcolor (int): Optional fill color for the area outside the transform in the output image. (Pillow>=5.0.0)
    """
    def __init__(self, fov=0, anglex=0, angley=0, anglez=0, shear=0,
                 translate=(0, 0), scale=(1, 1), resample='bilinear', fillcolor=(0, 0, 0)):

        assert all([isinstance(anglex, (tuple, list)) or anglex >= 0,
                    isinstance(angley, (tuple, list)) or angley >= 0,
                    isinstance(anglez, (tuple, list)) or anglez >= 0,
                    isinstance(shear, (tuple, list)) or shear >= 0]), \
            'All angles must be positive or tuple or list'
        assert 80 >= fov >= 0, 'fov should be in (0, 80)'
        self.fov = fov

        self.anglex = (-anglex, anglex) if isinstance(anglex, numbers.Number) else anglex
        self.angley = (-angley, angley) if isinstance(angley, numbers.Number) else angley
        self.anglez = (-anglez, anglez) if isinstance(anglez, numbers.Number) else anglez
        self.shear = (-shear, shear) if isinstance(shear, numbers.Number) else shear

        assert isinstance(translate, (tuple, list)) and len(translate) == 2, \
            "translate should be a list or tuple and it must be of length 2."
        assert all([0.0 <= i <= 1.0 for i in translate]), "translation values should be between 0 and 1"
        self.translate = translate

        if scale is not None:
            assert isinstance(scale, (tuple, list)) and len(scale) == 2, \
                "scale should be a list or tuple and it must be of length 2."
            assert all([s > 0 for s in scale]), "scale values should be positive"
        self.scale = scale

        self.resample = resample
        self.fillcolor = fillcolor

    @staticmethod
    def get_params(fov_range, anglex_ranges, angley_ranges, anglez_ranges, shear_ranges,
                   translate, scale_ranges,  img_size):
        """Get parameters for perspective transformation
        Returns:
            sequence: params to be passed to the perspective transformation
        """
        fov = 90 + random.uniform(-fov_range, fov_range)
        anglex = random.uniform(anglex_ranges[0], anglex_ranges[1])
        angley = random.uniform(angley_ranges[0], angley_ranges[1])
        anglez = random.uniform(anglez_ranges[0], anglez_ranges[1])
        shear = random.uniform(shear_ranges[0], shear_ranges[1])

        max_dx = translate[0] * img_size[1]
        max_dy = translate[1] * img_size[0]
        translations = (np.round(random.uniform(-max_dx, max_dx)),
                        np.round(random.uniform(-max_dy, max_dy)))

        scale = (random.uniform(1 / scale_ranges[0], scale_ranges[0]),
                 random.uniform(1 / scale_ranges[1], scale_ranges[1]))

        return fov, anglex, angley, anglez, shear, translations, scale

    def __call__(self, imgs):
        """
            imgs (np.ndarray): Image sequence (time*height*width*channel) to be transformed.
        Returns:
            np.ndarray: Perspective transformed image sequence.
        """
        ret = self.get_params(self.fov, self.anglex, self.angley, self.anglez, self.shear,
                              self.translate, self.scale, imgs[0, ...].shape)
        # Apply to all images
        output_imgs = []
        for I in imgs:
            output_imgs.append(F.perspective(I, *ret, resample=self.resample, fillcolor=self.fillcolor))
        return np.array(output_imgs)

    def __repr__(self):
        s = '{name}(degrees={degrees}'
        if self.translate is not None:
            s += ', translate={translate}'
        if self.scale is not None:
            s += ', scale={scale}'
        if self.shear is not None:
            s += ', shear={shear}'
        if self.resample > 0:
            s += ', resample={resample}'
        if self.fillcolor != 0:
            s += ', fillcolor={fillcolor}'
        s += ')'
        d = dict(self.__dict__)
        d['resample'] = d['resample']
        return s.format(name=self.__class__.__name__, **d)


class RandomErasing(object):
    """ Randomly selects a rectangle region in an image and erases its pixels.
        'Random Erasing Data Augmentation' by Zhong et al.
        See https://arxiv.org/pdf/1708.04896.pdf
    Args:
         p: probability that the random erasing operation will be performed.
         scale: range of proportion of erased area against input image.
         ratio: range of aspect ratio of erased area.
         value: erasing value. Default is 0. If a single int, it is used to
            erase all pixels. If a tuple of length 3, it is used to erase
            R, G, B channels respectively.
            If a str of 'random', erasing each pixel with random values.
         inplace: boolean to make this transform inplace. Default set to False.

    Returns:
        Erased Image.
    # Examples:
        >>> transform = transforms.Compose([
        >>> transforms.RandomHorizontalFlip(),
        >>> transforms.ToTensor(),
        >>> transforms.Normalize((0.485, 0.456, 0.406), (0.229, 0.224, 0.225)),
        >>> transforms.RandomErasing(),
        >>> ])
    """
    def __init__(self, p=0.5, scale=(0.02, 0.33), ratio=(0.3, 3.3), value=0, inplace=False):
        assert isinstance(value, (numbers.Number, str, tuple, list))
        if (scale[0] > scale[1]) or (ratio[0] > ratio[1]):
            warnings.warn("range should be of kind (min, max)")
        if scale[0] < 0 or scale[1] > 1:
            raise ValueError("range of scale should be between 0 and 1")
        if p < 0 or p > 1:
            raise ValueError("range of random erasing probability should be between 0 and 1")

        self.p = p
        self.scale = scale
        self.ratio = ratio
        self.value = value
        self.inplace = inplace

    @staticmethod
    def get_params(img, scale, ratio, value=0):
        """Get parameters for ``erase`` for a random erasing.

        Args:
            img (Tensor): Tensor image of size (C, H, W) to be erased.
            scale: range of proportion of erased area against input image.
            ratio: range of aspect ratio of erased area.

        Returns:
            tuple: params (i, j, h, w, v) to be passed to ``erase`` for random erasing.
        """
        img_c, img_h, img_w = img.shape
        area = img_h * img_w

        for attempt in range(10):
            erase_area = random.uniform(scale[0], scale[1]) * area
            aspect_ratio = random.uniform(ratio[0], ratio[1])

            h = int(round(math.sqrt(erase_area * aspect_ratio)))
            w = int(round(math.sqrt(erase_area / aspect_ratio)))

            if h < img_h and w < img_w:
                i = random.randint(0, img_h - h)
                j = random.randint(0, img_w - w)
                if isinstance(value, numbers.Number):
                    v = value
                elif isinstance(value, torch._six.string_classes):
                    v = torch.empty([img_c, h, w], dtype=torch.float32).normal_()
                elif isinstance(value, (list, tuple)):
                    v = torch.tensor(value, dtype=torch.float32).view(-1, 1, 1).expand(-1, h, w)
                return i, j, h, w, v

        # Return original image
        return 0, 0, img_h, img_w, img

    def __call__(self, imgs):
        """
        Args:
            imgs (Tensor): Tensor image sequence of size (channel*time*height*width) to be erased.

        Returns:
            Tensor: Erased Tensor image sequence.
        """
        if random.uniform(0, 1) < self.p:
            x, y, h, w, v = self.get_params(imgs[:, 0, :, :], scale=self.scale, ratio=self.ratio, value=self.value)
            # Apply to all images
            output_imgs = []
            for I in imgs.transpose(0, 1):
                output_imgs.append(FF.erase(I, x, y, h, w, v, self.inplace).unsqueeze(1))
            return torch.cat(output_imgs, dim=1)
        return imgs


class Resize(object):
    """Resize the input numpy ndarray to the given size.
    Args:
        size (sequence or int): Desired output size. If size is a sequence like
            (h, w), output size will be matched to this. If size is an int,
            smaller edge of the image will be matched to this number.
            i.e, if height > width, then image will be rescaled to
            (size * height / width, size)
        interpolation (int, optional): Desired interpolation. Default is
            ``cv2.INTER_CUBIC``, bicubic interpolation
    """
    def __init__(self, size, interpolation=cv2.INTER_CUBIC):
        assert isinstance(size, int) or (isinstance(size, collections.Iterable) and len(size) == 2)
        self.size = size
        self.interpolation = interpolation

    def __call__(self, imgs):
        """
        Args:
            imgs (numpy ndarray): Image sequence (time*height*width*channel) to be scaled.
        Returns:
            numpy ndarray: Rescaled image sequence.
        """
        # Apply to all images
        output_imgs = []
        for I in imgs:
            output_imgs.append(F.resize(I, self.size, self.interpolation))
        return np.array(output_imgs)

    def __repr__(self):
        interpolate_str = _cv2_interpolation_from_str[self.interpolation]
        return self.__class__.__name__ + '(size={0}, interpolation={1})'.format(self.size, interpolate_str)


class Normalize(object):
    """Normalize a tensor image sequence with mean and standard deviation.
    Given mean: ``(M1,...,Mn)`` and std: ``(S1,..,Sn)`` for ``n`` channels, this transform
    will normalize each channel of the input ``torch.*Tensor`` i.e.
    ``input[channel] = (input[channel] - mean[channel]) / std[channel]``

    .. note::
        This transform acts out of place, i.e., it does not mutates the input tensor.

    Args:
        mean (sequence): Sequence of means for each channel.
        std (sequence): Sequence of standard deviations for each channel.

    """
    def __init__(self, mean, std):
        self.mean = mean
        self.std = std

    def __call__(self, imgs):
        """
        Args:
            imgs (Tensor): Tensor image sequence of size (channel*time*height*width) to be normalized.

        Returns:
            Tensor: Normalized Tensor image sequence.
        """
        # Apply to all images
        output_imgs = []
        for I in imgs.transpose(0, 1):
            output_imgs.append(F.normalize(I, self.mean, self.std).unsqueeze(1))
        return torch.cat(output_imgs, dim=1)

    def __repr__(self):
        return self.__class__.__name__ + '(mean={0}, std={1})'.format(self.mean, self.std)


class ToTensor(object):
    """Convert a ``numpy.ndarray`` sequence to tensor.

    Converts a numpy.ndarray (time*height*width*channel) to
    a torch.FloatTensor of shape (channel*time*height*width)
    if the PIL Image belongs to one of the modes (L, LA, P, I, F, RGB, YCbCr, RGBA, CMYK, 1)
    or if the numpy.ndarray has dtype = np.uint8

    In the other cases, tensors are returned without scaling.
    """
    def __call__(self, imgs):
        """
        Args:
            imgs (numpy.ndarray): Image sequence to be converted to tensor.

        Returns:
            Tensor: Converted image sequence.
        """
        # Apply to all images
        output_imgs = []
        for I in imgs:
            output_imgs.append(F.to_tensor(I).unsqueeze(1))
        return torch.cat(output_imgs, dim=1)

    def __repr__(self):
        return self.__class__.__name__ + '()'