57 lines
2.0 KiB
Python
57 lines
2.0 KiB
Python
import mmcv
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import torch.nn as nn
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from mmcv.cnn import ConvModule
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from mmcv.runner import BaseModule
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# class SELayer(nn.Module):
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class SELayer(BaseModule):
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"""Squeeze-and-Excitation Module.
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Args:
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channels (int): The input (and output) channels of the SE layer.
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ratio (int): Squeeze ratio in SELayer, the intermediate channel will be
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``int(channels/ratio)``. Default: 16.
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conv_cfg (None or dict): Config dict for convolution layer.
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Default: None, which means using conv2d.
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act_cfg (dict or Sequence[dict]): Config dict for activation layer.
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If act_cfg is a dict, two activation layers will be configurated
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by this dict. If act_cfg is a sequence of dicts, the first
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activation layer will be configurated by the first dict and the
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second activation layer will be configurated by the second dict.
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Default: (dict(type='ReLU'), dict(type='Sigmoid'))
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"""
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def __init__(self,
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channels,
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ratio=16,
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conv_cfg=None,
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act_cfg=(dict(type='ReLU'), dict(type='Sigmoid')),
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init_cfg=None):
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super(SELayer, self).__init__(init_cfg)
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if isinstance(act_cfg, dict):
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act_cfg = (act_cfg, act_cfg)
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assert len(act_cfg) == 2
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assert mmcv.is_tuple_of(act_cfg, dict)
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self.global_avgpool = nn.AdaptiveAvgPool2d(1)
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self.conv1 = ConvModule(
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in_channels=channels,
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out_channels=int(channels / ratio),
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kernel_size=1,
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stride=1,
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conv_cfg=conv_cfg,
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act_cfg=act_cfg[0])
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self.conv2 = ConvModule(
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in_channels=int(channels / ratio),
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out_channels=channels,
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kernel_size=1,
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stride=1,
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conv_cfg=conv_cfg,
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act_cfg=act_cfg[1])
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def forward(self, x):
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out = self.global_avgpool(x)
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out = self.conv1(out)
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out = self.conv2(out)
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return x * out
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