Graduate ConvNeXt to main TorchVision area

docs/source/models.rst

@@ -89,6 +89,10 @@ You can construct a model with random weights by calling its constructor:
     vit_b_32 = models.vit_b_32()
     vit_l_16 = models.vit_l_16()
     vit_l_32 = models.vit_l_32()
+    convnext_tiny = models.convnext_tiny()
+    convnext_small = models.convnext_small()
+    convnext_base = models.convnext_base()
+    convnext_large = models.convnext_large()
 
 We provide pre-trained models, using the PyTorch :mod:`torch.utils.model_zoo`.
 These can be constructed by passing ``pretrained=True``:
@@ -136,6 +140,10 @@ These can be constructed by passing ``pretrained=True``:
     vit_b_32 = models.vit_b_32(pretrained=True)
     vit_l_16 = models.vit_l_16(pretrained=True)
     vit_l_32 = models.vit_l_32(pretrained=True)
+    convnext_tiny = models.convnext_tiny(pretrained=True)
+    convnext_small = models.convnext_small(pretrained=True)
+    convnext_base = models.convnext_base(pretrained=True)
+    convnext_large = models.convnext_large(pretrained=True)
 
 Instancing a pre-trained model will download its weights to a cache directory.
 This directory can be set using the `TORCH_HOME` environment variable. See
@@ -248,10 +256,10 @@ vit_b_16                          81.072          95.318
 vit_b_32                          75.912          92.466
 vit_l_16                          79.662          94.638
 vit_l_32                          76.972          93.070
-convnext_tiny (prototype)         82.520          96.146
-convnext_small (prototype)        83.616          96.650
-convnext_base (prototype)         84.062          96.870
-convnext_large (prototype)        84.414          96.976
+convnext_tiny                     82.520          96.146
+convnext_small                    83.616          96.650
+convnext_base                     84.062          96.870
+convnext_large                    84.414          96.976
 ================================  =============   =============
 
 
@@ -467,6 +475,18 @@ VisionTransformer
     vit_l_16
     vit_l_32
 
+ConvNeXt
+--------
+
+.. autosummary::
+    :toctree: generated/
+    :template: function.rst
+
+    convnext_tiny
+    convnext_small
+    convnext_base
+    convnext_large
+
 Quantized Models
 ----------------
 

hubconf.py

@@ -2,6 +2,7 @@
 dependencies = ["torch"]
 
 from torchvision.models.alexnet import alexnet
+from torchvision.models.convnext import convnext_tiny, convnext_small, convnext_base, convnext_large
 from torchvision.models.densenet import densenet121, densenet169, densenet201, densenet161
 from torchvision.models.efficientnet import (
     efficientnet_b0,

torchvision/models/__init__.py

@@ -1,4 +1,5 @@
 from .alexnet import *
+from .convnext import *
 from .resnet import *
 from .vgg import *
 from .squeezenet import *

torchvision/models/convnext.py

@@ -0,0 +1,271 @@
+from functools import partial
+from typing import Any, Callable, Dict, List, Optional, Sequence
+
+import torch
+from torch import nn, Tensor
+from torch.nn import functional as F
+
+from .._internally_replaced_utils import load_state_dict_from_url
+from ..ops.misc import ConvNormActivation
+from ..ops.stochastic_depth import StochasticDepth
+from ..utils import _log_api_usage_once
+
+
+__all__ = [
+    "ConvNeXt",
+    "convnext_tiny",
+    "convnext_small",
+    "convnext_base",
+    "convnext_large",
+]
+
+
+_MODELS_URLS: Dict[str, Optional[str]] = {
+    "convnext_tiny": "https://download.pytorch.org/models/convnext_tiny-983f1562.pth",
+    "convnext_small": "https://download.pytorch.org/models/convnext_small-0c510722.pth",
+    "convnext_base": "https://download.pytorch.org/models/convnext_base-6075fbad.pth",
+    "convnext_large": "https://download.pytorch.org/models/convnext_large-ea097f82.pth",
+}
+
+
+class LayerNorm2d(nn.LayerNorm):
+    def forward(self, x: Tensor) -> Tensor:
+        x = x.permute(0, 2, 3, 1)
+        x = F.layer_norm(x, self.normalized_shape, self.weight, self.bias, self.eps)
+        x = x.permute(0, 3, 1, 2)
+        return x
+
+
+class Permute(nn.Module):
+    def __init__(self, dims: List[int]):
+        super().__init__()
+        self.dims = dims
+
+    def forward(self, x):
+        return torch.permute(x, self.dims)
+
+
+class CNBlock(nn.Module):
+    def __init__(
+        self,
+        dim,
+        layer_scale: float,
+        stochastic_depth_prob: float,
+        norm_layer: Optional[Callable[..., nn.Module]] = None,
+    ) -> None:
+        super().__init__()
+        if norm_layer is None:
+            norm_layer = partial(nn.LayerNorm, eps=1e-6)
+
+        self.block = nn.Sequential(
+            nn.Conv2d(dim, dim, kernel_size=7, padding=3, groups=dim, bias=True),
+            Permute([0, 2, 3, 1]),
+            norm_layer(dim),
+            nn.Linear(in_features=dim, out_features=4 * dim, bias=True),
+            nn.GELU(),
+            nn.Linear(in_features=4 * dim, out_features=dim, bias=True),
+            Permute([0, 3, 1, 2]),
+        )
+        self.layer_scale = nn.Parameter(torch.ones(dim, 1, 1) * layer_scale)
+        self.stochastic_depth = StochasticDepth(stochastic_depth_prob, "row")
+
+    def forward(self, input: Tensor) -> Tensor:
+        result = self.layer_scale * self.block(input)
+        result = self.stochastic_depth(result)
+        result += input
+        return result
+
+
+class CNBlockConfig:
+    # Stores information listed at Section 3 of the ConvNeXt paper
+    def __init__(
+        self,
+        input_channels: int,
+        out_channels: Optional[int],
+        num_layers: int,
+    ) -> None:
+        self.input_channels = input_channels
+        self.out_channels = out_channels
+        self.num_layers = num_layers
+
+    def __repr__(self) -> str:
+        s = self.__class__.__name__ + "("
+        s += "input_channels={input_channels}"
+        s += ", out_channels={out_channels}"
+        s += ", num_layers={num_layers}"
+        s += ")"
+        return s.format(**self.__dict__)
+
+
+class ConvNeXt(nn.Module):
+    def __init__(
+        self,
+        block_setting: List[CNBlockConfig],
+        stochastic_depth_prob: float = 0.0,
+        layer_scale: float = 1e-6,
+        num_classes: int = 1000,
+        block: Optional[Callable[..., nn.Module]] = None,
+        norm_layer: Optional[Callable[..., nn.Module]] = None,
+        **kwargs: Any,
+    ) -> None:
+        super().__init__()
+        _log_api_usage_once(self)
+
+        if not block_setting:
+            raise ValueError("The block_setting should not be empty")
+        elif not (isinstance(block_setting, Sequence) and all([isinstance(s, CNBlockConfig) for s in block_setting])):
+            raise TypeError("The block_setting should be List[CNBlockConfig]")
+
+        if block is None:
+            block = CNBlock
+
+        if norm_layer is None:
+            norm_layer = partial(LayerNorm2d, eps=1e-6)
+
+        layers: List[nn.Module] = []
+
+        # Stem
+        firstconv_output_channels = block_setting[0].input_channels
+        layers.append(
+            ConvNormActivation(
+                3,
+                firstconv_output_channels,
+                kernel_size=4,
+                stride=4,
+                padding=0,
+                norm_layer=norm_layer,
+                activation_layer=None,
+                bias=True,
+            )
+        )
+
+        total_stage_blocks = sum(cnf.num_layers for cnf in block_setting)
+        stage_block_id = 0
+        for cnf in block_setting:
+            # Bottlenecks
+            stage: List[nn.Module] = []
+            for _ in range(cnf.num_layers):
+                # adjust stochastic depth probability based on the depth of the stage block
+                sd_prob = stochastic_depth_prob * stage_block_id / (total_stage_blocks - 1.0)
+                stage.append(block(cnf.input_channels, layer_scale, sd_prob))
+                stage_block_id += 1
+            layers.append(nn.Sequential(*stage))
+            if cnf.out_channels is not None:
+                # Downsampling
+                layers.append(
+                    nn.Sequential(
+                        norm_layer(cnf.input_channels),
+                        nn.Conv2d(cnf.input_channels, cnf.out_channels, kernel_size=2, stride=2),
+                    )
+                )
+
+        self.features = nn.Sequential(*layers)
+        self.avgpool = nn.AdaptiveAvgPool2d(1)
+
+        lastblock = block_setting[-1]
+        lastconv_output_channels = (
+            lastblock.out_channels if lastblock.out_channels is not None else lastblock.input_channels
+        )
+        self.classifier = nn.Sequential(
+            norm_layer(lastconv_output_channels), nn.Flatten(1), nn.Linear(lastconv_output_channels, num_classes)
+        )
+
+        for m in self.modules():
+            if isinstance(m, (nn.Conv2d, nn.Linear)):
+                nn.init.trunc_normal_(m.weight, std=0.02)
+                if m.bias is not None:
+                    nn.init.zeros_(m.bias)
+
+    def _forward_impl(self, x: Tensor) -> Tensor:
+        x = self.features(x)
+        x = self.avgpool(x)
+        x = self.classifier(x)
+        return x
+
+    def forward(self, x: Tensor) -> Tensor:
+        return self._forward_impl(x)
+
+
+def _convnext(
+    arch: str,
+    block_setting: List[CNBlockConfig],
+    stochastic_depth_prob: float,
+    pretrained: bool,
+    progress: bool,
+    **kwargs: Any,
+) -> ConvNeXt:
+    model = ConvNeXt(block_setting, stochastic_depth_prob=stochastic_depth_prob, **kwargs)
+    if pretrained:
+        if arch not in _MODELS_URLS:
+            raise ValueError(f"No checkpoint is available for model type {arch}")
+        state_dict = load_state_dict_from_url(_MODELS_URLS[arch], progress=progress)
+        model.load_state_dict(state_dict)
+    return model
+
+
+def convnext_tiny(*, pretrained: bool = False, progress: bool = True, **kwargs: Any) -> ConvNeXt:
+    r"""ConvNeXt Tiny model architecture from the
+    `"A ConvNet for the 2020s" <https://arxiv.org/abs/2201.03545>`_ paper.
+    Args:
+        pretrained (bool): If True, returns a model pre-trained on ImageNet
+        progress (bool): If True, displays a progress bar of the download to stderr
+    """
+    block_setting = [
+        CNBlockConfig(96, 192, 3),
+        CNBlockConfig(192, 384, 3),
+        CNBlockConfig(384, 768, 9),
+        CNBlockConfig(768, None, 3),
+    ]
+    stochastic_depth_prob = kwargs.pop("stochastic_depth_prob", 0.1)
+    return _convnext("convnext_tiny", block_setting, stochastic_depth_prob, pretrained, progress, **kwargs)
+
+
+def convnext_small(*, pretrained: bool = False, progress: bool = True, **kwargs: Any) -> ConvNeXt:
+    r"""ConvNeXt Small model architecture from the
+    `"A ConvNet for the 2020s" <https://arxiv.org/abs/2201.03545>`_ paper.
+    Args:
+        pretrained (bool): If True, returns a model pre-trained on ImageNet
+        progress (bool): If True, displays a progress bar of the download to stderr
+    """
+    block_setting = [
+        CNBlockConfig(96, 192, 3),
+        CNBlockConfig(192, 384, 3),
+        CNBlockConfig(384, 768, 27),
+        CNBlockConfig(768, None, 3),
+    ]
+    stochastic_depth_prob = kwargs.pop("stochastic_depth_prob", 0.4)
+    return _convnext("convnext_small", block_setting, stochastic_depth_prob, pretrained, progress, **kwargs)
+
+
+def convnext_base(*, pretrained: bool = False, progress: bool = True, **kwargs: Any) -> ConvNeXt:
+    r"""ConvNeXt Base model architecture from the
+    `"A ConvNet for the 2020s" <https://arxiv.org/abs/2201.03545>`_ paper.
+    Args:
+        pretrained (bool): If True, returns a model pre-trained on ImageNet
+        progress (bool): If True, displays a progress bar of the download to stderr
+    """
+    block_setting = [
+        CNBlockConfig(128, 256, 3),
+        CNBlockConfig(256, 512, 3),
+        CNBlockConfig(512, 1024, 27),
+        CNBlockConfig(1024, None, 3),
+    ]
+    stochastic_depth_prob = kwargs.pop("stochastic_depth_prob", 0.5)
+    return _convnext("convnext_base", block_setting, stochastic_depth_prob, pretrained, progress, **kwargs)
+
+
+def convnext_large(*, pretrained: bool = False, progress: bool = True, **kwargs: Any) -> ConvNeXt:
+    r"""ConvNeXt Large model architecture from the
+    `"A ConvNet for the 2020s" <https://arxiv.org/abs/2201.03545>`_ paper.
+    Args:
+        pretrained (bool): If True, returns a model pre-trained on ImageNet
+        progress (bool): If True, displays a progress bar of the download to stderr
+    """
+    block_setting = [
+        CNBlockConfig(192, 384, 3),
+        CNBlockConfig(384, 768, 3),
+        CNBlockConfig(768, 1536, 27),
+        CNBlockConfig(1536, None, 3),
+    ]
+    stochastic_depth_prob = kwargs.pop("stochastic_depth_prob", 0.5)
+    return _convnext("convnext_large", block_setting, stochastic_depth_prob, pretrained, progress, **kwargs)