Enable semantic segmentation backbone and head

CHANGELOG.md

@@ -15,13 +15,15 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
 ### Changed
 
+- Split `backbone` argument to `SemanticSegmentation` into `backbone` and `head` arguments ([#412](https://github.com/PyTorchLightning/lightning-flash/pull/412))
 
 ### Deprecated
 
 
 ### Fixed
 
 - Fixed a bug where the `DefaultDataKeys.METADATA` couldn't be a dict ([#393](https://github.com/PyTorchLightning/lightning-flash/pull/393))
+- Fixed a bug where the `SemanticSegmentation` task would not work as expected with finetuning callbacks ([#412](https://github.com/PyTorchLightning/lightning-flash/pull/412))
 
 ## [0.3.2] - 2021-06-08
 

flash/core/model.py

@@ -488,8 +488,8 @@ def available_backbones(cls) -> List[str]:
         return registry.available_keys()
 
     @classmethod
-    def available_models(cls) -> List[str]:
-        registry: Optional[FlashRegistry] = getattr(cls, "models", None)
+    def available_heads(cls) -> List[str]:
+        registry: Optional[FlashRegistry] = getattr(cls, "heads", None)
         if registry is None:
             return []
         return registry.available_keys()

flash/image/segmentation/backbones.py

@@ -11,106 +11,48 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-import os
-import warnings
 from functools import partial
 
-import torch.nn as nn
-from deprecate import deprecated
-from pytorch_lightning.utilities import rank_zero_warn
-
 from flash.core.registry import FlashRegistry
-from flash.core.utilities.imports import _BOLTS_AVAILABLE, _TORCHVISION_AVAILABLE
+from flash.core.utilities.imports import _TORCHVISION_AVAILABLE
 from flash.image.backbones import catch_url_error
 
 if _TORCHVISION_AVAILABLE:
-    from torchvision.models import segmentation
-
-if _BOLTS_AVAILABLE:
-    if os.getenv("WARN_MISSING_PACKAGE") == "0":
-        with warnings.catch_warnings(record=True) as w:
-            from pl_bolts.models.vision import UNet
-    else:
-        from pl_bolts.models.vision import UNet
+    from torchvision.models import mobilenetv3, resnet
 
-FCN_MODELS = ["fcn_resnet50", "fcn_resnet101"]
-DEEPLABV3_MODELS = ["deeplabv3_resnet50", "deeplabv3_resnet101", "deeplabv3_mobilenet_v3_large"]
-LRASPP_MODELS = ["lraspp_mobilenet_v3_large"]
+RESNET_MODELS = ["resnet50", "resnet101"]
+MOBILENET_MODELS = ["mobilenet_v3_large"]
 
 SEMANTIC_SEGMENTATION_BACKBONES = FlashRegistry("backbones")
 
 if _TORCHVISION_AVAILABLE:
 
-    def _fn_fcn_deeplabv3(model_name: str, num_classes: int, pretrained: bool = True, **kwargs) -> nn.Module:
-        model: nn.Module = getattr(segmentation, model_name, None)(pretrained, **kwargs)
-        in_channels = model.classifier[-1].in_channels
-        model.classifier[-1] = nn.Conv2d(in_channels, num_classes, 1)
-        return model
-
-    for model_name in FCN_MODELS + DEEPLABV3_MODELS:
-        _type = model_name.split("_")[0]
+    def _load_resnet(model_name: str, pretrained: bool = True):
+        backbone = resnet.__dict__[model_name](
+            pretrained=pretrained,
+            replace_stride_with_dilation=[False, True, True],
+        )
+        return backbone
 
+    for model_name in RESNET_MODELS:
         SEMANTIC_SEGMENTATION_BACKBONES(
-            fn=catch_url_error(partial(_fn_fcn_deeplabv3, model_name)),
+            fn=catch_url_error(partial(_load_resnet, model_name)),
             name=model_name,
             namespace="image/segmentation",
             package="torchvision",
-            type=_type
         )
 
-    SEMANTIC_SEGMENTATION_BACKBONES(
-        fn=deprecated(
-            target=None,
-            stream=partial(warnings.warn, category=UserWarning),
-            deprecated_in="0.3.1",
-            remove_in="0.5.0",
-            template_mgs="The 'torchvision/fcn_resnet50' backbone has been deprecated since v%(deprecated_in)s in "
-            "favor of 'fcn_resnet50'. It will be removed in v%(remove_in)s.",
-        )(SEMANTIC_SEGMENTATION_BACKBONES.get("fcn_resnet50")),
-        name="torchvision/fcn_resnet50",
-    )
-
-    SEMANTIC_SEGMENTATION_BACKBONES(
-        fn=deprecated(
-            target=None,
-            stream=partial(warnings.warn, category=UserWarning),
-            deprecated_in="0.3.1",
-            remove_in="0.5.0",
-            template_mgs="The 'torchvision/fcn_resnet101' backbone has been deprecated since v%(deprecated_in)s in "
-            "favor of 'fcn_resnet101'. It will be removed in v%(remove_in)s.",
-        )(SEMANTIC_SEGMENTATION_BACKBONES.get("fcn_resnet101")),
-        name="torchvision/fcn_resnet101",
-    )
-
-    def _fn_lraspp(model_name: str, num_classes: int, pretrained: bool = True, **kwargs) -> nn.Module:
-        model: nn.Module = getattr(segmentation, model_name, None)(pretrained, **kwargs)
-
-        low_channels = model.classifier.low_classifier.in_channels
-        high_channels = model.classifier.high_classifier.in_channels
-
-        model.classifier.low_classifier = nn.Conv2d(low_channels, num_classes, 1)
-        model.classifier.high_classifier = nn.Conv2d(high_channels, num_classes, 1)
-        return model
+    def _load_mobilenetv3(model_name: str, pretrained: bool = True):
+        backbone = mobilenetv3.__dict__[model_name](
+            pretrained=pretrained,
+            _dilated=True,
+        )
+        return backbone
 
-    for model_name in LRASPP_MODELS:
+    for model_name in MOBILENET_MODELS:
         SEMANTIC_SEGMENTATION_BACKBONES(
-            fn=catch_url_error(partial(_fn_lraspp, model_name)),
+            fn=catch_url_error(partial(_load_mobilenetv3, model_name)),
             name=model_name,
             namespace="image/segmentation",
             package="torchvision",
-            type="lraspp"
         )
-
-if _BOLTS_AVAILABLE:
-
-    def load_bolts_unet(num_classes: int, pretrained: bool = False, **kwargs) -> nn.Module:
-        if pretrained:
-            rank_zero_warn(
-                "No pretrained weights are available for the pl_bolts.models.vision.UNet model. This backbone will be "
-                "initialized with random weights!", UserWarning
-            )
-        return UNet(num_classes, **kwargs)
-
-    SEMANTIC_SEGMENTATION_BACKBONES(
-        fn=load_bolts_unet, name="unet", namespace="image/segmentation", package="bolts", type="unet"
-    )

flash/image/segmentation/heads.py

@@ -0,0 +1,116 @@
+# Copyright The PyTorch Lightning team.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+import os
+import warnings
+from functools import partial
+
+import torch.nn as nn
+from pytorch_lightning.utilities import rank_zero_warn
+from pytorch_lightning.utilities.exceptions import MisconfigurationException
+
+from flash.core.registry import FlashRegistry
+from flash.core.utilities.imports import _BOLTS_AVAILABLE, _TORCHVISION_AVAILABLE
+
+if _TORCHVISION_AVAILABLE:
+    from torchvision.models import MobileNetV3, ResNet
+    from torchvision.models._utils import IntermediateLayerGetter
+    from torchvision.models.segmentation.deeplabv3 import DeepLabHead, DeepLabV3
+    from torchvision.models.segmentation.fcn import FCN, FCNHead
+    from torchvision.models.segmentation.lraspp import LRASPP
+
+if _BOLTS_AVAILABLE:
+    if os.getenv("WARN_MISSING_PACKAGE") == "0":
+        with warnings.catch_warnings(record=True) as w:
+            from pl_bolts.models.vision import UNet
+    else:
+        from pl_bolts.models.vision import UNet
+
+RESNET_MODELS = ["resnet50", "resnet101"]
+MOBILENET_MODELS = ["mobilenet_v3_large"]
+
+SEMANTIC_SEGMENTATION_HEADS = FlashRegistry("backbones")
+
+if _TORCHVISION_AVAILABLE:
+
+    def _get_backbone_meta(backbone):
+        """Adapted from torchvision.models.segmentation.segmentation._segm_model:
+        https://github.com/pytorch/vision/blob/master/torchvision/models/segmentation/segmentation.py#L25
+        """
+        if isinstance(backbone, ResNet):
+            out_layer = 'layer4'
+            out_inplanes = 2048
+            aux_layer = 'layer3'
+            aux_inplanes = 1024
+        elif isinstance(backbone, MobileNetV3):
+            backbone = backbone.features
+            # Gather the indices of blocks which are strided. These are the locations of C1, ..., Cn-1 blocks.
+            # The first and last blocks are always included because they are the C0 (conv1) and Cn.
+            stage_indices = [i for i, b in enumerate(backbone) if getattr(b, "_is_cn", False)]
+            stage_indices = [0] + stage_indices + [len(backbone) - 1]
+            out_pos = stage_indices[-1]  # use C5 which has output_stride = 16
+            out_layer = str(out_pos)
+            out_inplanes = backbone[out_pos].out_channels
+            aux_pos = stage_indices[-4]  # use C2 here which has output_stride = 8
+            aux_layer = str(aux_pos)
+            aux_inplanes = backbone[aux_pos].out_channels
+        else:
+            raise MisconfigurationException(
+                f"{type(backbone)} backbone is not currently supported for semantic segmentation."
+            )
+        return backbone, out_layer, out_inplanes, aux_layer, aux_inplanes
+
+    def _load_fcn_deeplabv3(model_name, backbone, num_classes):
+        backbone, out_layer, out_inplanes, aux_layer, aux_inplanes = _get_backbone_meta(backbone)
+
+        return_layers = {out_layer: 'out'}
+        backbone = IntermediateLayerGetter(backbone, return_layers=return_layers)
+
+        model_map = {
+            "deeplabv3": (DeepLabHead, DeepLabV3),
+            "fcn": (FCNHead, FCN),
+        }
+        classifier = model_map[model_name][0](out_inplanes, num_classes)
+        base_model = model_map[model_name][1]
+
+        return base_model(backbone, classifier, None)
+
+    for model_name in ["fcn", "deeplabv3"]:
+        SEMANTIC_SEGMENTATION_HEADS(
+            fn=partial(_load_fcn_deeplabv3, model_name),
+            name=model_name,
+            namespace="image/segmentation",
+            package="torchvision",
+        )
+
+    def _load_lraspp(backbone, num_classes):
+        backbone, high_pos, high_channels, low_pos, low_channels = _get_backbone_meta(backbone)
+        backbone = IntermediateLayerGetter(backbone, return_layers={low_pos: 'low', high_pos: 'high'})
+        return LRASPP(backbone, low_channels, high_channels, num_classes)
+
+    SEMANTIC_SEGMENTATION_HEADS(
+        fn=_load_lraspp,
+        name="lraspp",
+        namespace="image/segmentation",
+        package="torchvision",
+    )
+
+if _BOLTS_AVAILABLE:
+
+    def _load_bolts_unet(_, num_classes: int, **kwargs) -> nn.Module:
+        rank_zero_warn("The UNet model does not require a backbone, so the backbone will be ignored.", UserWarning)
+        return UNet(num_classes, **kwargs)
+
+    SEMANTIC_SEGMENTATION_HEADS(
+        fn=_load_bolts_unet, name="unet", namespace="image/segmentation", package="bolts", type="unet"
+    )

flash/image/segmentation/model.py

@@ -24,6 +24,7 @@
 from flash.core.registry import FlashRegistry
 from flash.core.utilities.imports import _KORNIA_AVAILABLE, _TIMM_AVAILABLE, _TORCHVISION_AVAILABLE
 from flash.image.segmentation.backbones import SEMANTIC_SEGMENTATION_BACKBONES
+from flash.image.segmentation.heads import SEMANTIC_SEGMENTATION_HEADS
 from flash.image.segmentation.serialization import SegmentationLabels
 
 if _KORNIA_AVAILABLE:
@@ -54,14 +55,15 @@ class SemanticSegmentation(ClassificationTask):
 
     Args:
         num_classes: Number of classes to classify.
-        backbone: A string or (model, num_features) tuple to use to compute image features,
-            defaults to ``"torchvision/fcn_resnet50"``.
+        backbone: A string or model to use to compute image features.
         backbone_kwargs: Additional arguments for the backbone configuration.
-        pretrained: Use a pretrained backbone, defaults to ``False``.
-        loss_fn: Loss function for training, defaults to :func:`torch.nn.functional.cross_entropy`.
-        optimizer: Optimizer to use for training, defaults to :class:`torch.optim.AdamW`.
-        metrics: Metrics to compute for training and evaluation, defaults to :class:`torchmetrics.IoU`.
-        learning_rate: Learning rate to use for training, defaults to ``1e-3``.
+        head: A string or (model, num_features) tuple to use to compute image features.
+        head_kwargs: Additional arguments for the head configuration.
+        pretrained: Use a pretrained backbone.
+        loss_fn: Loss function for training.
+        optimizer: Optimizer to use for training.
+        metrics: Metrics to compute for training and evaluation.
+        learning_rate: Learning rate to use for training.
         multi_label: Whether the targets are multi-label or not.
         serializer: The :class:`~flash.core.data.process.Serializer` to use when serializing prediction outputs.
     """
@@ -70,11 +72,15 @@ class SemanticSegmentation(ClassificationTask):
 
     backbones: FlashRegistry = SEMANTIC_SEGMENTATION_BACKBONES
 
+    heads: FlashRegistry = SEMANTIC_SEGMENTATION_HEADS
+
     def __init__(
         self,
         num_classes: int,
-        backbone: Union[str, Tuple[nn.Module, int]] = "fcn_resnet50",
+        backbone: Union[str, nn.Module] = "resnet50",
         backbone_kwargs: Optional[Dict] = None,
+        head: str = "fcn",
+        head_kwargs: Optional[Dict] = None,
         pretrained: bool = True,
         loss_fn: Optional[Callable] = None,
         optimizer: Type[torch.optim.Optimizer] = torch.optim.AdamW,
@@ -113,8 +119,15 @@ def __init__(
         if not backbone_kwargs:
             backbone_kwargs = {}
 
-        # TODO: pretrained to True causes some issues
-        self.backbone = self.backbones.get(backbone)(num_classes, pretrained=pretrained, **backbone_kwargs)
+        if not head_kwargs:
+            head_kwargs = {}
+
+        if isinstance(backbone, nn.Module):
+            self.backbone = backbone
+        else:
+            self.backbone = self.backbones.get(backbone)(pretrained=pretrained, **backbone_kwargs)
+
+        self.head = self.heads.get(head)(self.backbone, num_classes, **head_kwargs)
 
     def training_step(self, batch: Any, batch_idx: int) -> Any:
         batch = (batch[DefaultDataKeys.INPUT], batch[DefaultDataKeys.TARGET])
@@ -134,8 +147,7 @@ def predict_step(self, batch: Any, batch_idx: int, dataloader_idx: int = 0) -> A
         return batch
 
     def forward(self, x) -> torch.Tensor:
-        # infer the image to the model
-        res = self.backbone(x)
+        res = self.head(x)
 
         # some frameworks like torchvision return a dict.
         # In particular, torchvision segmentation models return the output logits
@@ -145,7 +157,7 @@ def forward(self, x) -> torch.Tensor:
         elif torch.is_tensor(res):
             out = res
         else:
-            raise NotImplementedError(f"Unsupported output type: {type(out)}")
+            raise NotImplementedError(f"Unsupported output type: {type(res)}")
 
         return out
 

flash_examples/finetuning/semantic_segmentation.py

@@ -29,31 +29,33 @@
     train_folder="data/CameraRGB",
     train_target_folder="data/CameraSeg",
     batch_size=4,
-    val_split=0.3,
-    image_size=(200, 200),  # (600, 800)
+    val_split=0.1,
+    image_size=(200, 200),
     num_classes=21,
 )
 
 # 2.2 Visualise the samples
 datamodule.show_train_batch(["load_sample", "post_tensor_transform"])
 
-# 3.a List available backbones
-print(SemanticSegmentation.available_backbones())
+# 3.a List available backbones and heads
+print(f"Backbones: {SemanticSegmentation.available_backbones()}")
+print(f"Heads: {SemanticSegmentation.available_heads()}")
 
 # 3.b Build the model
 model = SemanticSegmentation(
-    backbone="fcn_resnet50", num_classes=datamodule.num_classes, serializer=SegmentationLabels(visualize=True)
+    backbone="mobilenet_v3_large",
+    head="fcn",
+    num_classes=datamodule.num_classes,
+    serializer=SegmentationLabels(visualize=True),
 )
 
 # 4. Create the trainer.
-trainer = flash.Trainer(
-    max_epochs=1,
-    fast_dev_run=1,
-)
+trainer = flash.Trainer(fast_dev_run=True)
 
 # 5. Train the model
 trainer.finetune(model, datamodule=datamodule, strategy="freeze")
 
+# 6. Segment a few images!
 predictions = model.predict([
     "data/CameraRGB/F61-1.png",
     "data/CameraRGB/F62-1.png",