-
Notifications
You must be signed in to change notification settings - Fork 136
/
random_erasing.py
173 lines (165 loc) · 6.46 KB
/
random_erasing.py
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
"""
This implementation is based on
https://github.com/rwightman/pytorch-image-models/blob/master/timm/data/random_erasing.py
pulished under an Apache License 2.0.
"""
import math
import random
import torch
def _get_pixels(
per_pixel, rand_color, patch_size, dtype=torch.float32, device="cuda"
):
# NOTE I've seen CUDA illegal memory access errors being caused by the normal_()
# paths, flip the order so normal is run on CPU if this becomes a problem
# Issue has been fixed in master https://github.com/pytorch/pytorch/issues/19508
if per_pixel:
return torch.empty(patch_size, dtype=dtype, device=device).normal_()
elif rand_color:
return torch.empty(
(patch_size[0], 1, 1), dtype=dtype, device=device
).normal_()
else:
return torch.zeros((patch_size[0], 1, 1), dtype=dtype, device=device)
class RandomErasing:
"""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
This variant of RandomErasing is intended to be applied to either a batch
or single image tensor after it has been normalized by dataset mean and std.
Args:
probability: Probability that the Random Erasing operation will be performed.
min_area: Minimum percentage of erased area wrt input image area.
max_area: Maximum percentage of erased area wrt input image area.
min_aspect: Minimum aspect ratio of erased area.
mode: pixel color mode, one of 'const', 'rand', or 'pixel'
'const' - erase block is constant color of 0 for all channels
'rand' - erase block is same per-channel random (normal) color
'pixel' - erase block is per-pixel random (normal) color
max_count: maximum number of erasing blocks per image, area per box is scaled by count.
per-image count is randomly chosen between 1 and this value.
"""
def __init__(
self,
probability=0.5,
min_area=0.02,
max_area=1 / 3,
min_aspect=0.3,
max_aspect=None,
mode="const",
min_count=1,
max_count=None,
num_splits=0,
device="cuda",
cube=True,
):
self.probability = probability
self.min_area = min_area
self.max_area = max_area
max_aspect = max_aspect or 1 / min_aspect
self.log_aspect_ratio = (math.log(min_aspect), math.log(max_aspect))
self.min_count = min_count
self.max_count = max_count or min_count
self.num_splits = num_splits
mode = mode.lower()
self.rand_color = False
self.per_pixel = False
self.cube = cube
if mode == "rand":
self.rand_color = True # per block random normal
elif mode == "pixel":
self.per_pixel = True # per pixel random normal
else:
assert not mode or mode == "const"
self.device = device
def _erase(self, img, chan, img_h, img_w, dtype):
if random.random() > self.probability:
return
area = img_h * img_w
count = (
self.min_count
if self.min_count == self.max_count
else random.randint(self.min_count, self.max_count)
)
for _ in range(count):
for _ in range(10):
target_area = (
random.uniform(self.min_area, self.max_area) * area / count
)
aspect_ratio = math.exp(random.uniform(*self.log_aspect_ratio))
h = int(round(math.sqrt(target_area * aspect_ratio)))
w = int(round(math.sqrt(target_area / aspect_ratio)))
if w < img_w and h < img_h:
top = random.randint(0, img_h - h)
left = random.randint(0, img_w - w)
img[:, top : top + h, left : left + w] = _get_pixels(
self.per_pixel,
self.rand_color,
(chan, h, w),
dtype=dtype,
device=self.device,
)
break
def _erase_cube(
self,
img,
batch_start,
batch_size,
chan,
img_h,
img_w,
dtype,
):
if random.random() > self.probability:
return
area = img_h * img_w
count = (
self.min_count
if self.min_count == self.max_count
else random.randint(self.min_count, self.max_count)
)
for _ in range(count):
for _ in range(100):
target_area = (
random.uniform(self.min_area, self.max_area) * area / count
)
aspect_ratio = math.exp(random.uniform(*self.log_aspect_ratio))
h = int(round(math.sqrt(target_area * aspect_ratio)))
w = int(round(math.sqrt(target_area / aspect_ratio)))
if w < img_w and h < img_h:
top = random.randint(0, img_h - h)
left = random.randint(0, img_w - w)
for i in range(batch_start, batch_size):
img_instance = img[i]
img_instance[
:, top : top + h, left : left + w
] = _get_pixels(
self.per_pixel,
self.rand_color,
(chan, h, w),
dtype=dtype,
device=self.device,
)
break
def __call__(self, input):
if len(input.size()) == 3:
self._erase(input, *input.size(), input.dtype)
else:
batch_size, chan, img_h, img_w = input.size()
# skip first slice of batch if num_splits is set (for clean portion of samples)
batch_start = (
batch_size // self.num_splits if self.num_splits > 1 else 0
)
if self.cube:
self._erase_cube(
input,
batch_start,
batch_size,
chan,
img_h,
img_w,
input.dtype,
)
else:
for i in range(batch_start, batch_size):
self._erase(input[i], chan, img_h, img_w, input.dtype)
return input