# -*- coding: utf-8 -*-
# Copyright (c) Facebook, Inc. and its affiliates.
"""
Implement many useful :class:`Augmentation`.
"""
import numpy as np
import sys
from fvcore.transforms.transform import (
BlendTransform,
CropTransform,
HFlipTransform,
NoOpTransform,
VFlipTransform,
)
from PIL import Image
from .augmentation import Augmentation, _transform_to_aug
from .transform import ExtentTransform, ResizeTransform, RotationTransform
__all__ = [
"RandomApply",
"RandomBrightness",
"RandomContrast",
"RandomCrop",
"RandomExtent",
"RandomFlip",
"RandomSaturation",
"RandomLighting",
"RandomRotation",
"Resize",
"ResizeShortestEdge",
"RandomCrop_CategoryAreaConstraint",
]
class RandomApply(Augmentation):
"""
Randomly apply an augmentation with a given probability.
"""
def __init__(self, tfm_or_aug, prob=0.5):
"""
Args:
tfm_or_aug (Transform, Augmentation): the transform or augmentation
to be applied. It can either be a `Transform` or `Augmentation`
instance.
prob (float): probability between 0.0 and 1.0 that
the wrapper transformation is applied
"""
super().__init__()
self.aug = _transform_to_aug(tfm_or_aug)
assert 0.0 <= prob <= 1.0, f"Probablity must be between 0.0 and 1.0 (given: {prob})"
self.prob = prob
def get_transform(self, *args):
do = self._rand_range() < self.prob
if do:
return self.aug.get_transform(*args)
else:
return NoOpTransform()
def __call__(self, aug_input):
do = self._rand_range() < self.prob
if do:
return self.aug(aug_input)
else:
return NoOpTransform()
class RandomFlip(Augmentation):
"""
Flip the image horizontally or vertically with the given probability.
"""
def __init__(self, prob=0.5, *, horizontal=True, vertical=False):
"""
Args:
prob (float): probability of flip.
horizontal (boolean): whether to apply horizontal flipping
vertical (boolean): whether to apply vertical flipping
"""
super().__init__()
if horizontal and vertical:
raise ValueError("Cannot do both horiz and vert. Please use two Flip instead.")
if not horizontal and not vertical:
raise ValueError("At least one of horiz or vert has to be True!")
self._init(locals())
def get_transform(self, image):
h, w = image.shape[:2]
do = self._rand_range() < self.prob
if do:
if self.horizontal:
return HFlipTransform(w)
elif self.vertical:
return VFlipTransform(h)
else:
return NoOpTransform()
class Resize(Augmentation):
""" Resize image to a fixed target size"""
def __init__(self, shape, interp=Image.BILINEAR):
"""
Args:
shape: (h, w) tuple or a int
interp: PIL interpolation method
"""
if isinstance(shape, int):
shape = (shape, shape)
shape = tuple(shape)
self._init(locals())
def get_transform(self, image):
return ResizeTransform(
image.shape[0], image.shape[1], self.shape[0], self.shape[1], self.interp
)
class ResizeShortestEdge(Augmentation):
"""
Scale the shorter edge to the given size, with a limit of `max_size` on the longer edge.
If `max_size` is reached, then downscale so that the longer edge does not exceed max_size.
"""
def __init__(
self, short_edge_length, max_size=sys.maxsize, sample_style="range", interp=Image.BILINEAR
):
"""
Args:
short_edge_length (list[int]): If ``sample_style=="range"``,
a [min, max] interval from which to sample the shortest edge length.
If ``sample_style=="choice"``, a list of shortest edge lengths to sample from.
max_size (int): maximum allowed longest edge length.
sample_style (str): either "range" or "choice".
"""
super().__init__()
assert sample_style in ["range", "choice"], sample_style
self.is_range = sample_style == "range"
if isinstance(short_edge_length, int):
short_edge_length = (short_edge_length, short_edge_length)
if self.is_range:
assert len(short_edge_length) == 2, (
"short_edge_length must be two values using 'range' sample style."
f" Got {short_edge_length}!"
)
self._init(locals())
def get_transform(self, image):
h, w = image.shape[:2]
if self.is_range:
size = np.random.randint(self.short_edge_length[0], self.short_edge_length[1] + 1)
else:
size = np.random.choice(self.short_edge_length)
if size == 0:
return NoOpTransform()
scale = size * 1.0 / min(h, w)
if h < w:
newh, neww = size, scale * w
else:
newh, neww = scale * h, size
if max(newh, neww) > self.max_size:
scale = self.max_size * 1.0 / max(newh, neww)
newh = newh * scale
neww = neww * scale
neww = int(neww + 0.5)
newh = int(newh + 0.5)
return ResizeTransform(h, w, newh, neww, self.interp)
class RandomRotation(Augmentation):
"""
This method returns a copy of this image, rotated the given
number of degrees counter clockwise around the given center.
"""
def __init__(self, angle, expand=True, center=None, sample_style="range", interp=None):
"""
Args:
angle (list[float]): If ``sample_style=="range"``,
a [min, max] interval from which to sample the angle (in degrees).
If ``sample_style=="choice"``, a list of angles to sample from
expand (bool): choose if the image should be resized to fit the whole
rotated image (default), or simply cropped
center (list[[float, float]]): If ``sample_style=="range"``,
a [[minx, miny], [maxx, maxy]] relative interval from which to sample the center,
[0, 0] being the top left of the image and [1, 1] the bottom right.
If ``sample_style=="choice"``, a list of centers to sample from
Default: None, which means that the center of rotation is the center of the image
center has no effect if expand=True because it only affects shifting
"""
super().__init__()
assert sample_style in ["range", "choice"], sample_style
self.is_range = sample_style == "range"
if isinstance(angle, (float, int)):
angle = (angle, angle)
if center is not None and isinstance(center[0], (float, int)):
center = (center, center)
self._init(locals())
def get_transform(self, image):
h, w = image.shape[:2]
center = None
if self.is_range:
angle = np.random.uniform(self.angle[0], self.angle[1])
if self.center is not None:
center = (
np.random.uniform(self.center[0][0], self.center[1][0]),
np.random.uniform(self.center[0][1], self.center[1][1]),
)
else:
angle = np.random.choice(self.angle)
if self.center is not None:
center = np.random.choice(self.center)
if center is not None:
center = (w * center[0], h * center[1]) # Convert to absolute coordinates
if angle % 360 == 0:
return NoOpTransform()
return RotationTransform(h, w, angle, expand=self.expand, center=center, interp=self.interp)
class RandomCrop(Augmentation):
"""
Randomly crop a subimage out of an image.
"""
def __init__(self, crop_type: str, crop_size):
"""
Args:
crop_type (str): one of "relative_range", "relative", "absolute", "absolute_range".
See `config/defaults.py` for explanation.
crop_size (tuple[float]): the relative ratio or absolute pixels of
height and width
"""
super().__init__()
assert crop_type in ["relative_range", "relative", "absolute", "absolute_range"]
self._init(locals())
def get_transform(self, image):
h, w = image.shape[:2]
croph, cropw = self.get_crop_size((h, w))
assert h >= croph and w >= cropw, "Shape computation in {} has bugs.".format(self)
h0 = np.random.randint(h - croph + 1)
w0 = np.random.randint(w - cropw + 1)
return CropTransform(w0, h0, cropw, croph)
def get_crop_size(self, image_size):
"""
Args:
image_size (tuple): height, width
Returns:
crop_size (tuple): height, width in absolute pixels
"""
h, w = image_size
if self.crop_type == "relative":
ch, cw = self.crop_size
return int(h * ch + 0.5), int(w * cw + 0.5)
elif self.crop_type == "relative_range":
crop_size = np.asarray(self.crop_size, dtype=np.float32)
ch, cw = crop_size + np.random.rand(2) * (1 - crop_size)
return int(h * ch + 0.5), int(w * cw + 0.5)
elif self.crop_type == "absolute":
return (min(self.crop_size[0], h), min(self.crop_size[1], w))
elif self.crop_type == "absolute_range":
assert self.crop_size[0] <= self.crop_size[1]
ch = np.random.randint(min(h, self.crop_size[0]), min(h, self.crop_size[1]) + 1)
cw = np.random.randint(min(w, self.crop_size[0]), min(w, self.crop_size[1]) + 1)
return ch, cw
else:
NotImplementedError("Unknown crop type {}".format(self.crop_type))
class RandomCrop_CategoryAreaConstraint(Augmentation):
"""
Similar to :class:`RandomCrop`, but find a cropping window such that no single category
occupies a ratio of more than `single_category_max_area` in semantic segmentation ground
truth, which can cause unstability in training. The function attempts to find such a valid
cropping window for at most 10 times.
"""
def __init__(
self,
crop_type: str,
crop_size,
single_category_max_area: float = 1.0,
ignored_category: int = None,
):
"""
Args:
crop_type, crop_size: same as in :class:`RandomCrop`
single_category_max_area: the maximum allowed area ratio of a
category. Set to 1.0 to disable
ignored_category: allow this category in the semantic segmentation
ground truth to exceed the area ratio. Usually set to the category
that's ignored in training.
"""
self.crop_aug = RandomCrop(crop_type, crop_size)
self._init(locals())
def get_transform(self, image, sem_seg):
if self.single_category_max_area >= 1.0:
return self.crop_aug.get_transform(image)
else:
h, w = sem_seg.shape
for _ in range(10):
crop_size = self.crop_aug.get_crop_size((h, w))
y0 = np.random.randint(h - crop_size[0] + 1)
x0 = np.random.randint(w - crop_size[1] + 1)
sem_seg_temp = sem_seg[y0 : y0 + crop_size[0], x0 : x0 + crop_size[1]]
labels, cnt = np.unique(sem_seg_temp, return_counts=True)
if self.ignored_category is not None:
cnt = cnt[labels != self.ignored_category]
if len(cnt) > 1 and np.max(cnt) < np.sum(cnt) * self.single_category_max_area:
break
crop_tfm = CropTransform(x0, y0, crop_size[1], crop_size[0])
return crop_tfm
class RandomExtent(Augmentation):
"""
Outputs an image by cropping a random "subrect" of the source image.
The subrect can be parameterized to include pixels outside the source image,
in which case they will be set to zeros (i.e. black). The size of the output
image will vary with the size of the random subrect.
"""
def __init__(self, scale_range, shift_range):
"""
Args:
output_size (h, w): Dimensions of output image
scale_range (l, h): Range of input-to-output size scaling factor
shift_range (x, y): Range of shifts of the cropped subrect. The rect
is shifted by [w / 2 * Uniform(-x, x), h / 2 * Uniform(-y, y)],
where (w, h) is the (width, height) of the input image. Set each
component to zero to crop at the image's center.
"""
super().__init__()
self._init(locals())
def get_transform(self, image):
img_h, img_w = image.shape[:2]
# Initialize src_rect to fit the input image.
src_rect = np.array([-0.5 * img_w, -0.5 * img_h, 0.5 * img_w, 0.5 * img_h])
# Apply a random scaling to the src_rect.
src_rect *= np.random.uniform(self.scale_range[0], self.scale_range[1])
# Apply a random shift to the coordinates origin.
src_rect[0::2] += self.shift_range[0] * img_w * (np.random.rand() - 0.5)
src_rect[1::2] += self.shift_range[1] * img_h * (np.random.rand() - 0.5)
# Map src_rect coordinates into image coordinates (center at corner).
src_rect[0::2] += 0.5 * img_w
src_rect[1::2] += 0.5 * img_h
return ExtentTransform(
src_rect=(src_rect[0], src_rect[1], src_rect[2], src_rect[3]),
output_size=(int(src_rect[3] - src_rect[1]), int(src_rect[2] - src_rect[0])),
)
class RandomContrast(Augmentation):
"""
Randomly transforms image contrast.
Contrast intensity is uniformly sampled in (intensity_min, intensity_max).
- intensity < 1 will reduce contrast
- intensity = 1 will preserve the input image
- intensity > 1 will increase contrast
See: https://pillow.readthedocs.io/en/3.0.x/reference/ImageEnhance.html
"""
def __init__(self, intensity_min, intensity_max):
"""
Args:
intensity_min (float): Minimum augmentation
intensity_max (float): Maximum augmentation
"""
super().__init__()
self._init(locals())
def get_transform(self, image):
w = np.random.uniform(self.intensity_min, self.intensity_max)
return BlendTransform(src_image=image.mean(), src_weight=1 - w, dst_weight=w)
class RandomBrightness(Augmentation):
"""
Randomly transforms image brightness.
Brightness intensity is uniformly sampled in (intensity_min, intensity_max).
- intensity < 1 will reduce brightness
- intensity = 1 will preserve the input image
- intensity > 1 will increase brightness
See: https://pillow.readthedocs.io/en/3.0.x/reference/ImageEnhance.html
"""
def __init__(self, intensity_min, intensity_max):
"""
Args:
intensity_min (float): Minimum augmentation
intensity_max (float): Maximum augmentation
"""
super().__init__()
self._init(locals())
def get_transform(self, image):
w = np.random.uniform(self.intensity_min, self.intensity_max)
return BlendTransform(src_image=0, src_weight=1 - w, dst_weight=w)
class RandomSaturation(Augmentation):
"""
Randomly transforms saturation of an RGB image.
Input images are assumed to have 'RGB' channel order.
Saturation intensity is uniformly sampled in (intensity_min, intensity_max).
- intensity < 1 will reduce saturation (make the image more grayscale)
- intensity = 1 will preserve the input image
- intensity > 1 will increase saturation
See: https://pillow.readthedocs.io/en/3.0.x/reference/ImageEnhance.html
"""
def __init__(self, intensity_min, intensity_max):
"""
Args:
intensity_min (float): Minimum augmentation (1 preserves input).
intensity_max (float): Maximum augmentation (1 preserves input).
"""
super().__init__()
self._init(locals())
def get_transform(self, image):
assert image.shape[-1] == 3, "RandomSaturation only works on RGB images"
w = np.random.uniform(self.intensity_min, self.intensity_max)
grayscale = image.dot([0.299, 0.587, 0.114])[:, :, np.newaxis]
return BlendTransform(src_image=grayscale, src_weight=1 - w, dst_weight=w)
class RandomLighting(Augmentation):
"""
The "lighting" augmentation described in AlexNet, using fixed PCA over ImageNet.
Input images are assumed to have 'RGB' channel order.
The degree of color jittering is randomly sampled via a normal distribution,
with standard deviation given by the scale parameter.
"""
def __init__(self, scale):
"""
Args:
scale (float): Standard deviation of principal component weighting.
"""
super().__init__()
self._init(locals())
self.eigen_vecs = np.array(
[[-0.5675, 0.7192, 0.4009], [-0.5808, -0.0045, -0.8140], [-0.5836, -0.6948, 0.4203]]
)
self.eigen_vals = np.array([0.2175, 0.0188, 0.0045])
def get_transform(self, image):
assert image.shape[-1] == 3, "RandomLighting only works on RGB images"
weights = np.random.normal(scale=self.scale, size=3)
return BlendTransform(
src_image=self.eigen_vecs.dot(weights * self.eigen_vals), src_weight=1.0, dst_weight=1.0
)