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# Copyright (c) OpenMMLab. All rights reserved. | |
import torch | |
import torch.nn as nn | |
from mmcv.cnn import ConvModule | |
from mmengine.model import BaseModule | |
from mmengine.utils import digit_version, is_tuple_of | |
from torch import Tensor | |
from mmdet.utils import MultiConfig, OptConfigType, OptMultiConfig | |
class SELayer(BaseModule): | |
"""Squeeze-and-Excitation Module. | |
Args: | |
channels (int): The input (and output) channels of the SE layer. | |
ratio (int): Squeeze ratio in SELayer, the intermediate channel will be | |
``int(channels/ratio)``. Defaults to 16. | |
conv_cfg (None or dict): Config dict for convolution layer. | |
Defaults to None, which means using conv2d. | |
act_cfg (dict or Sequence[dict]): Config dict for activation layer. | |
If act_cfg is a dict, two activation layers will be configurated | |
by this dict. If act_cfg is a sequence of dicts, the first | |
activation layer will be configurated by the first dict and the | |
second activation layer will be configurated by the second dict. | |
Defaults to (dict(type='ReLU'), dict(type='Sigmoid')) | |
init_cfg (dict or list[dict], optional): Initialization config dict. | |
Defaults to None | |
""" | |
def __init__(self, | |
channels: int, | |
ratio: int = 16, | |
conv_cfg: OptConfigType = None, | |
act_cfg: MultiConfig = (dict(type='ReLU'), | |
dict(type='Sigmoid')), | |
init_cfg: OptMultiConfig = None) -> None: | |
super().__init__(init_cfg=init_cfg) | |
if isinstance(act_cfg, dict): | |
act_cfg = (act_cfg, act_cfg) | |
assert len(act_cfg) == 2 | |
assert is_tuple_of(act_cfg, dict) | |
self.global_avgpool = nn.AdaptiveAvgPool2d(1) | |
self.conv1 = ConvModule( | |
in_channels=channels, | |
out_channels=int(channels / ratio), | |
kernel_size=1, | |
stride=1, | |
conv_cfg=conv_cfg, | |
act_cfg=act_cfg[0]) | |
self.conv2 = ConvModule( | |
in_channels=int(channels / ratio), | |
out_channels=channels, | |
kernel_size=1, | |
stride=1, | |
conv_cfg=conv_cfg, | |
act_cfg=act_cfg[1]) | |
def forward(self, x: Tensor) -> Tensor: | |
"""Forward function for SELayer.""" | |
out = self.global_avgpool(x) | |
out = self.conv1(out) | |
out = self.conv2(out) | |
return x * out | |
class DyReLU(BaseModule): | |
"""Dynamic ReLU (DyReLU) module. | |
See `Dynamic ReLU <https://arxiv.org/abs/2003.10027>`_ for details. | |
Current implementation is specialized for task-aware attention in DyHead. | |
HSigmoid arguments in default act_cfg follow DyHead official code. | |
https://github.com/microsoft/DynamicHead/blob/master/dyhead/dyrelu.py | |
Args: | |
channels (int): The input (and output) channels of DyReLU module. | |
ratio (int): Squeeze ratio in Squeeze-and-Excitation-like module, | |
the intermediate channel will be ``int(channels/ratio)``. | |
Defaults to 4. | |
conv_cfg (None or dict): Config dict for convolution layer. | |
Defaults to None, which means using conv2d. | |
act_cfg (dict or Sequence[dict]): Config dict for activation layer. | |
If act_cfg is a dict, two activation layers will be configurated | |
by this dict. If act_cfg is a sequence of dicts, the first | |
activation layer will be configurated by the first dict and the | |
second activation layer will be configurated by the second dict. | |
Defaults to (dict(type='ReLU'), dict(type='HSigmoid', bias=3.0, | |
divisor=6.0)) | |
init_cfg (dict or list[dict], optional): Initialization config dict. | |
Defaults to None | |
""" | |
def __init__(self, | |
channels: int, | |
ratio: int = 4, | |
conv_cfg: OptConfigType = None, | |
act_cfg: MultiConfig = (dict(type='ReLU'), | |
dict( | |
type='HSigmoid', | |
bias=3.0, | |
divisor=6.0)), | |
init_cfg: OptMultiConfig = None) -> None: | |
super().__init__(init_cfg=init_cfg) | |
if isinstance(act_cfg, dict): | |
act_cfg = (act_cfg, act_cfg) | |
assert len(act_cfg) == 2 | |
assert is_tuple_of(act_cfg, dict) | |
self.channels = channels | |
self.expansion = 4 # for a1, b1, a2, b2 | |
self.global_avgpool = nn.AdaptiveAvgPool2d(1) | |
self.conv1 = ConvModule( | |
in_channels=channels, | |
out_channels=int(channels / ratio), | |
kernel_size=1, | |
stride=1, | |
conv_cfg=conv_cfg, | |
act_cfg=act_cfg[0]) | |
self.conv2 = ConvModule( | |
in_channels=int(channels / ratio), | |
out_channels=channels * self.expansion, | |
kernel_size=1, | |
stride=1, | |
conv_cfg=conv_cfg, | |
act_cfg=act_cfg[1]) | |
def forward(self, x: Tensor) -> Tensor: | |
"""Forward function.""" | |
coeffs = self.global_avgpool(x) | |
coeffs = self.conv1(coeffs) | |
coeffs = self.conv2(coeffs) - 0.5 # value range: [-0.5, 0.5] | |
a1, b1, a2, b2 = torch.split(coeffs, self.channels, dim=1) | |
a1 = a1 * 2.0 + 1.0 # [-1.0, 1.0] + 1.0 | |
a2 = a2 * 2.0 # [-1.0, 1.0] | |
out = torch.max(x * a1 + b1, x * a2 + b2) | |
return out | |
class ChannelAttention(BaseModule): | |
"""Channel attention Module. | |
Args: | |
channels (int): The input (and output) channels of the attention layer. | |
init_cfg (dict or list[dict], optional): Initialization config dict. | |
Defaults to None | |
""" | |
def __init__(self, channels: int, init_cfg: OptMultiConfig = None) -> None: | |
super().__init__(init_cfg=init_cfg) | |
self.global_avgpool = nn.AdaptiveAvgPool2d(1) | |
self.fc = nn.Conv2d(channels, channels, 1, 1, 0, bias=True) | |
if digit_version(torch.__version__) < (1, 7, 0): | |
self.act = nn.Hardsigmoid() | |
else: | |
self.act = nn.Hardsigmoid(inplace=True) | |
def forward(self, x: Tensor) -> Tensor: | |
"""Forward function for ChannelAttention.""" | |
with torch.cuda.amp.autocast(enabled=False): | |
out = self.global_avgpool(x) | |
out = self.fc(out) | |
out = self.act(out) | |
return x * out | |