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# Copyright (c) OpenMMLab. All rights reserved. | |
import copy | |
import torch | |
import torch.nn as nn | |
import torch.nn.functional as F | |
import torch.utils.checkpoint as cp | |
from mmcv.cnn import build_conv_layer, build_norm_layer | |
from ..builder import BACKBONES | |
from .resnet import Bottleneck, ResNet | |
class SCConv(nn.Module): | |
"""SCConv (Self-calibrated Convolution) | |
Args: | |
in_channels (int): The input channels of the SCConv. | |
out_channels (int): The output channel of the SCConv. | |
stride (int): stride of SCConv. | |
pooling_r (int): size of pooling for scconv. | |
conv_cfg (dict): dictionary to construct and config conv layer. | |
Default: None | |
norm_cfg (dict): dictionary to construct and config norm layer. | |
Default: dict(type='BN') | |
""" | |
def __init__(self, | |
in_channels, | |
out_channels, | |
stride, | |
pooling_r, | |
conv_cfg=None, | |
norm_cfg=dict(type='BN', momentum=0.1)): | |
# Protect mutable default arguments | |
norm_cfg = copy.deepcopy(norm_cfg) | |
super().__init__() | |
assert in_channels == out_channels | |
self.k2 = nn.Sequential( | |
nn.AvgPool2d(kernel_size=pooling_r, stride=pooling_r), | |
build_conv_layer( | |
conv_cfg, | |
in_channels, | |
in_channels, | |
kernel_size=3, | |
stride=1, | |
padding=1, | |
bias=False), | |
build_norm_layer(norm_cfg, in_channels)[1], | |
) | |
self.k3 = nn.Sequential( | |
build_conv_layer( | |
conv_cfg, | |
in_channels, | |
in_channels, | |
kernel_size=3, | |
stride=1, | |
padding=1, | |
bias=False), | |
build_norm_layer(norm_cfg, in_channels)[1], | |
) | |
self.k4 = nn.Sequential( | |
build_conv_layer( | |
conv_cfg, | |
in_channels, | |
in_channels, | |
kernel_size=3, | |
stride=stride, | |
padding=1, | |
bias=False), | |
build_norm_layer(norm_cfg, out_channels)[1], | |
nn.ReLU(inplace=True), | |
) | |
def forward(self, x): | |
"""Forward function.""" | |
identity = x | |
out = torch.sigmoid( | |
torch.add(identity, F.interpolate(self.k2(x), | |
identity.size()[2:]))) | |
out = torch.mul(self.k3(x), out) | |
out = self.k4(out) | |
return out | |
class SCBottleneck(Bottleneck): | |
"""SC(Self-calibrated) Bottleneck. | |
Args: | |
in_channels (int): The input channels of the SCBottleneck block. | |
out_channels (int): The output channel of the SCBottleneck block. | |
""" | |
pooling_r = 4 | |
def __init__(self, in_channels, out_channels, **kwargs): | |
super().__init__(in_channels, out_channels, **kwargs) | |
self.mid_channels = out_channels // self.expansion // 2 | |
self.norm1_name, norm1 = build_norm_layer( | |
self.norm_cfg, self.mid_channels, postfix=1) | |
self.norm2_name, norm2 = build_norm_layer( | |
self.norm_cfg, self.mid_channels, postfix=2) | |
self.norm3_name, norm3 = build_norm_layer( | |
self.norm_cfg, out_channels, postfix=3) | |
self.conv1 = build_conv_layer( | |
self.conv_cfg, | |
in_channels, | |
self.mid_channels, | |
kernel_size=1, | |
stride=1, | |
bias=False) | |
self.add_module(self.norm1_name, norm1) | |
self.k1 = nn.Sequential( | |
build_conv_layer( | |
self.conv_cfg, | |
self.mid_channels, | |
self.mid_channels, | |
kernel_size=3, | |
stride=self.stride, | |
padding=1, | |
bias=False), | |
build_norm_layer(self.norm_cfg, self.mid_channels)[1], | |
nn.ReLU(inplace=True)) | |
self.conv2 = build_conv_layer( | |
self.conv_cfg, | |
in_channels, | |
self.mid_channels, | |
kernel_size=1, | |
stride=1, | |
bias=False) | |
self.add_module(self.norm2_name, norm2) | |
self.scconv = SCConv(self.mid_channels, self.mid_channels, self.stride, | |
self.pooling_r, self.conv_cfg, self.norm_cfg) | |
self.conv3 = build_conv_layer( | |
self.conv_cfg, | |
self.mid_channels * 2, | |
out_channels, | |
kernel_size=1, | |
stride=1, | |
bias=False) | |
self.add_module(self.norm3_name, norm3) | |
def forward(self, x): | |
"""Forward function.""" | |
def _inner_forward(x): | |
identity = x | |
out_a = self.conv1(x) | |
out_a = self.norm1(out_a) | |
out_a = self.relu(out_a) | |
out_a = self.k1(out_a) | |
out_b = self.conv2(x) | |
out_b = self.norm2(out_b) | |
out_b = self.relu(out_b) | |
out_b = self.scconv(out_b) | |
out = self.conv3(torch.cat([out_a, out_b], dim=1)) | |
out = self.norm3(out) | |
if self.downsample is not None: | |
identity = self.downsample(x) | |
out += identity | |
return out | |
if self.with_cp and x.requires_grad: | |
out = cp.checkpoint(_inner_forward, x) | |
else: | |
out = _inner_forward(x) | |
out = self.relu(out) | |
return out | |
class SCNet(ResNet): | |
"""SCNet backbone. | |
Improving Convolutional Networks with Self-Calibrated Convolutions, | |
Jiang-Jiang Liu, Qibin Hou, Ming-Ming Cheng, Changhu Wang, Jiashi Feng, | |
IEEE CVPR, 2020. | |
http://mftp.mmcheng.net/Papers/20cvprSCNet.pdf | |
Args: | |
depth (int): Depth of scnet, from {50, 101}. | |
in_channels (int): Number of input image channels. Normally 3. | |
base_channels (int): Number of base channels of hidden layer. | |
num_stages (int): SCNet stages, normally 4. | |
strides (Sequence[int]): Strides of the first block of each stage. | |
dilations (Sequence[int]): Dilation of each stage. | |
out_indices (Sequence[int]): Output from which stages. | |
style (str): `pytorch` or `caffe`. If set to "pytorch", the stride-two | |
layer is the 3x3 conv layer, otherwise the stride-two layer is | |
the first 1x1 conv layer. | |
deep_stem (bool): Replace 7x7 conv in input stem with 3 3x3 conv | |
avg_down (bool): Use AvgPool instead of stride conv when | |
downsampling in the bottleneck. | |
frozen_stages (int): Stages to be frozen (stop grad and set eval mode). | |
-1 means not freezing any parameters. | |
norm_cfg (dict): Dictionary to construct and config norm layer. | |
norm_eval (bool): Whether to set norm layers to eval mode, namely, | |
freeze running stats (mean and var). Note: Effect on Batch Norm | |
and its variants only. | |
with_cp (bool): Use checkpoint or not. Using checkpoint will save some | |
memory while slowing down the training speed. | |
zero_init_residual (bool): Whether to use zero init for last norm layer | |
in resblocks to let them behave as identity. | |
Example: | |
>>> from mmpose.models import SCNet | |
>>> import torch | |
>>> self = SCNet(depth=50, out_indices=(0, 1, 2, 3)) | |
>>> self.eval() | |
>>> inputs = torch.rand(1, 3, 224, 224) | |
>>> level_outputs = self.forward(inputs) | |
>>> for level_out in level_outputs: | |
... print(tuple(level_out.shape)) | |
(1, 256, 56, 56) | |
(1, 512, 28, 28) | |
(1, 1024, 14, 14) | |
(1, 2048, 7, 7) | |
""" | |
arch_settings = { | |
50: (SCBottleneck, [3, 4, 6, 3]), | |
101: (SCBottleneck, [3, 4, 23, 3]) | |
} | |
def __init__(self, depth, **kwargs): | |
if depth not in self.arch_settings: | |
raise KeyError(f'invalid depth {depth} for SCNet') | |
super().__init__(depth, **kwargs) | |