object_detection/mmdet/models/backbones/convnext.py [19:180]: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - class Block(nn.Module): r""" ConvNeXt Block. There are two equivalent implementations: (1) DwConv -> LayerNorm (channels_first) -> 1x1 Conv -> GELU -> 1x1 Conv; all in (N, C, H, W) (2) DwConv -> Permute to (N, H, W, C); LayerNorm (channels_last) -> Linear -> GELU -> Linear; Permute back We use (2) as we find it slightly faster in PyTorch Args: dim (int): Number of input channels. drop_path (float): Stochastic depth rate. Default: 0.0 layer_scale_init_value (float): Init value for Layer Scale. Default: 1e-6. """ def __init__(self, dim, drop_path=0., layer_scale_init_value=1e-6): super().__init__() self.dwconv = nn.Conv2d(dim, dim, kernel_size=7, padding=3, groups=dim) # depthwise conv self.norm = LayerNorm(dim, eps=1e-6) self.pwconv1 = nn.Linear(dim, 4 * dim) # pointwise/1x1 convs, implemented with linear layers self.act = nn.GELU() self.pwconv2 = nn.Linear(4 * dim, dim) self.gamma = nn.Parameter(layer_scale_init_value * torch.ones((dim)), requires_grad=True) if layer_scale_init_value > 0 else None self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity() def forward(self, x): input = x x = self.dwconv(x) x = x.permute(0, 2, 3, 1) # (N, C, H, W) -> (N, H, W, C) x = self.norm(x) x = self.pwconv1(x) x = self.act(x) x = self.pwconv2(x) if self.gamma is not None: x = self.gamma * x x = x.permute(0, 3, 1, 2) # (N, H, W, C) -> (N, C, H, W) x = input + self.drop_path(x) return x @BACKBONES.register_module() class ConvNeXt(nn.Module): r""" ConvNeXt A PyTorch impl of : `A ConvNet for the 2020s` - https://arxiv.org/pdf/2201.03545.pdf Args: in_chans (int): Number of input image channels. Default: 3 num_classes (int): Number of classes for classification head. Default: 1000 depths (tuple(int)): Number of blocks at each stage. Default: [3, 3, 9, 3] dims (int): Feature dimension at each stage. Default: [96, 192, 384, 768] drop_path_rate (float): Stochastic depth rate. Default: 0. layer_scale_init_value (float): Init value for Layer Scale. Default: 1e-6. head_init_scale (float): Init scaling value for classifier weights and biases. Default: 1. """ def __init__(self, in_chans=3, depths=[3, 3, 9, 3], dims=[96, 192, 384, 768], drop_path_rate=0., layer_scale_init_value=1e-6, out_indices=[0, 1, 2, 3], ): super().__init__() self.downsample_layers = nn.ModuleList() # stem and 3 intermediate downsampling conv layers stem = nn.Sequential( nn.Conv2d(in_chans, dims[0], kernel_size=4, stride=4), LayerNorm(dims[0], eps=1e-6, data_format="channels_first") ) self.downsample_layers.append(stem) for i in range(3): downsample_layer = nn.Sequential( LayerNorm(dims[i], eps=1e-6, data_format="channels_first"), nn.Conv2d(dims[i], dims[i+1], kernel_size=2, stride=2), ) self.downsample_layers.append(downsample_layer) self.stages = nn.ModuleList() # 4 feature resolution stages, each consisting of multiple residual blocks dp_rates=[x.item() for x in torch.linspace(0, drop_path_rate, sum(depths))] cur = 0 for i in range(4): stage = nn.Sequential( *[Block(dim=dims[i], drop_path=dp_rates[cur + j], layer_scale_init_value=layer_scale_init_value) for j in range(depths[i])] ) self.stages.append(stage) cur += depths[i] self.out_indices = out_indices norm_layer = partial(LayerNorm, eps=1e-6, data_format="channels_first") for i_layer in range(4): layer = norm_layer(dims[i_layer]) layer_name = f'norm{i_layer}' self.add_module(layer_name, layer) self.apply(self._init_weights) def _init_weights(self, m): if isinstance(m, (nn.Conv2d, nn.Linear)): trunc_normal_(m.weight, std=.02) nn.init.constant_(m.bias, 0) def init_weights(self, pretrained=None): """Initialize the weights in backbone. Args: pretrained (str, optional): Path to pre-trained weights. Defaults to None. """ def _init_weights(m): if isinstance(m, nn.Linear): trunc_normal_(m.weight, std=.02) if isinstance(m, nn.Linear) and m.bias is not None: nn.init.constant_(m.bias, 0) elif isinstance(m, nn.LayerNorm): nn.init.constant_(m.bias, 0) nn.init.constant_(m.weight, 1.0) if isinstance(pretrained, str): self.apply(_init_weights) logger = get_root_logger() load_checkpoint(self, pretrained, strict=False, logger=logger) elif pretrained is None: self.apply(_init_weights) else: raise TypeError('pretrained must be a str or None') def forward_features(self, x): outs = [] for i in range(4): x = self.downsample_layers[i](x) x = self.stages[i](x) if i in self.out_indices: norm_layer = getattr(self, f'norm{i}') x_out = norm_layer(x) outs.append(x_out) return tuple(outs) def forward(self, x): x = self.forward_features(x) return x class LayerNorm(nn.Module): r""" LayerNorm that supports two data formats: channels_last (default) or channels_first. The ordering of the dimensions in the inputs. channels_last corresponds to inputs with shape (batch_size, height, width, channels) while channels_first corresponds to inputs with shape (batch_size, channels, height, width). """ def __init__(self, normalized_shape, eps=1e-6, data_format="channels_last"): super().__init__() self.weight = nn.Parameter(torch.ones(normalized_shape)) self.bias = nn.Parameter(torch.zeros(normalized_shape)) self.eps = eps self.data_format = data_format if self.data_format not in ["channels_last", "channels_first"]: raise NotImplementedError self.normalized_shape = (normalized_shape, ) def forward(self, x): if self.data_format == "channels_last": return F.layer_norm(x, self.normalized_shape, self.weight, self.bias, self.eps) elif self.data_format == "channels_first": u = x.mean(1, keepdim=True) s = (x - u).pow(2).mean(1, keepdim=True) x = (x - u) / torch.sqrt(s + self.eps) x = self.weight[:, None, None] * x + self.bias[:, None, None] return x - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - semantic_segmentation/backbone/convnext.py [21:182]: - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - class Block(nn.Module): r""" ConvNeXt Block. There are two equivalent implementations: (1) DwConv -> LayerNorm (channels_first) -> 1x1 Conv -> GELU -> 1x1 Conv; all in (N, C, H, W) (2) DwConv -> Permute to (N, H, W, C); LayerNorm (channels_last) -> Linear -> GELU -> Linear; Permute back We use (2) as we find it slightly faster in PyTorch Args: dim (int): Number of input channels. drop_path (float): Stochastic depth rate. Default: 0.0 layer_scale_init_value (float): Init value for Layer Scale. Default: 1e-6. """ def __init__(self, dim, drop_path=0., layer_scale_init_value=1e-6): super().__init__() self.dwconv = nn.Conv2d(dim, dim, kernel_size=7, padding=3, groups=dim) # depthwise conv self.norm = LayerNorm(dim, eps=1e-6) self.pwconv1 = nn.Linear(dim, 4 * dim) # pointwise/1x1 convs, implemented with linear layers self.act = nn.GELU() self.pwconv2 = nn.Linear(4 * dim, dim) self.gamma = nn.Parameter(layer_scale_init_value * torch.ones((dim)), requires_grad=True) if layer_scale_init_value > 0 else None self.drop_path = DropPath(drop_path) if drop_path > 0. else nn.Identity() def forward(self, x): input = x x = self.dwconv(x) x = x.permute(0, 2, 3, 1) # (N, C, H, W) -> (N, H, W, C) x = self.norm(x) x = self.pwconv1(x) x = self.act(x) x = self.pwconv2(x) if self.gamma is not None: x = self.gamma * x x = x.permute(0, 3, 1, 2) # (N, H, W, C) -> (N, C, H, W) x = input + self.drop_path(x) return x @BACKBONES.register_module() class ConvNeXt(nn.Module): r""" ConvNeXt A PyTorch impl of : `A ConvNet for the 2020s` - https://arxiv.org/pdf/2201.03545.pdf Args: in_chans (int): Number of input image channels. Default: 3 num_classes (int): Number of classes for classification head. Default: 1000 depths (tuple(int)): Number of blocks at each stage. Default: [3, 3, 9, 3] dims (int): Feature dimension at each stage. Default: [96, 192, 384, 768] drop_path_rate (float): Stochastic depth rate. Default: 0. layer_scale_init_value (float): Init value for Layer Scale. Default: 1e-6. head_init_scale (float): Init scaling value for classifier weights and biases. Default: 1. """ def __init__(self, in_chans=3, depths=[3, 3, 9, 3], dims=[96, 192, 384, 768], drop_path_rate=0., layer_scale_init_value=1e-6, out_indices=[0, 1, 2, 3], ): super().__init__() self.downsample_layers = nn.ModuleList() # stem and 3 intermediate downsampling conv layers stem = nn.Sequential( nn.Conv2d(in_chans, dims[0], kernel_size=4, stride=4), LayerNorm(dims[0], eps=1e-6, data_format="channels_first") ) self.downsample_layers.append(stem) for i in range(3): downsample_layer = nn.Sequential( LayerNorm(dims[i], eps=1e-6, data_format="channels_first"), nn.Conv2d(dims[i], dims[i+1], kernel_size=2, stride=2), ) self.downsample_layers.append(downsample_layer) self.stages = nn.ModuleList() # 4 feature resolution stages, each consisting of multiple residual blocks dp_rates=[x.item() for x in torch.linspace(0, drop_path_rate, sum(depths))] cur = 0 for i in range(4): stage = nn.Sequential( *[Block(dim=dims[i], drop_path=dp_rates[cur + j], layer_scale_init_value=layer_scale_init_value) for j in range(depths[i])] ) self.stages.append(stage) cur += depths[i] self.out_indices = out_indices norm_layer = partial(LayerNorm, eps=1e-6, data_format="channels_first") for i_layer in range(4): layer = norm_layer(dims[i_layer]) layer_name = f'norm{i_layer}' self.add_module(layer_name, layer) self.apply(self._init_weights) def _init_weights(self, m): if isinstance(m, (nn.Conv2d, nn.Linear)): trunc_normal_(m.weight, std=.02) nn.init.constant_(m.bias, 0) def init_weights(self, pretrained=None): """Initialize the weights in backbone. Args: pretrained (str, optional): Path to pre-trained weights. Defaults to None. """ def _init_weights(m): if isinstance(m, nn.Linear): trunc_normal_(m.weight, std=.02) if isinstance(m, nn.Linear) and m.bias is not None: nn.init.constant_(m.bias, 0) elif isinstance(m, nn.LayerNorm): nn.init.constant_(m.bias, 0) nn.init.constant_(m.weight, 1.0) if isinstance(pretrained, str): self.apply(_init_weights) logger = get_root_logger() load_checkpoint(self, pretrained, strict=False, logger=logger) elif pretrained is None: self.apply(_init_weights) else: raise TypeError('pretrained must be a str or None') def forward_features(self, x): outs = [] for i in range(4): x = self.downsample_layers[i](x) x = self.stages[i](x) if i in self.out_indices: norm_layer = getattr(self, f'norm{i}') x_out = norm_layer(x) outs.append(x_out) return tuple(outs) def forward(self, x): x = self.forward_features(x) return x class LayerNorm(nn.Module): r""" LayerNorm that supports two data formats: channels_last (default) or channels_first. The ordering of the dimensions in the inputs. channels_last corresponds to inputs with shape (batch_size, height, width, channels) while channels_first corresponds to inputs with shape (batch_size, channels, height, width). """ def __init__(self, normalized_shape, eps=1e-6, data_format="channels_last"): super().__init__() self.weight = nn.Parameter(torch.ones(normalized_shape)) self.bias = nn.Parameter(torch.zeros(normalized_shape)) self.eps = eps self.data_format = data_format if self.data_format not in ["channels_last", "channels_first"]: raise NotImplementedError self.normalized_shape = (normalized_shape, ) def forward(self, x): if self.data_format == "channels_last": return F.layer_norm(x, self.normalized_shape, self.weight, self.bias, self.eps) elif self.data_format == "channels_first": u = x.mean(1, keepdim=True) s = (x - u).pow(2).mean(1, keepdim=True) x = (x - u) / torch.sqrt(s + self.eps) x = self.weight[:, None, None] * x + self.bias[:, None, None] return x - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -