[WIP] add style transfer task with pystiche

.github/workflows/ci-testing.yml

@@ -37,6 +37,10 @@ jobs:
             python-version: 3.8
             requires: 'latest'
             topic: 'text'
+          - os: ubuntu-20.04
+            python-version: 3.8
+            requires: 'latest'
+            topic: 'image_style_transfer'
 
     # Timeout: https://stackoverflow.com/a/59076067/4521646
     timeout-minutes: 35

CHANGELOG.md

@@ -22,6 +22,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 - Refactor preprocess_cls to preprocess, add Serializer, add DataPipelineState ([#229](https://github.com/PyTorchLightning/lightning-flash/pull/229))
 - Added Semantic Segmentation task ([#239](https://github.com/PyTorchLightning/lightning-flash/pull/239) [#287](https://github.com/PyTorchLightning/lightning-flash/pull/287) [#290](https://github.com/PyTorchLightning/lightning-flash/pull/290))
 - Added Object detection prediction example ([#283](https://github.com/PyTorchLightning/lightning-flash/pull/283))
+- Added Style Transfer task and accompanying finetuning and prediction examples ([#262](https://github.com/PyTorchLightning/lightning-flash/pull/262))
 
 ### Changed
 

docs/source/index.rst

@@ -30,6 +30,7 @@ Lightning Flash
    reference/object_detection
    reference/video_classification
    reference/semantic_segmentation
+   reference/style_transfer
 
 .. toctree::
    :maxdepth: 1

docs/source/reference/style_transfer.rst

@@ -0,0 +1,82 @@
+##############
+Style Transfer
+##############
+
+********
+The task
+********
+
+The Neural Style Transfer Task is an optimization method which extract the style from an image and apply it another image while preserving its content.
+The goal is that the output image looks like the content image, but “painted” in the style of the style reference image.
+
+.. image:: https://raw.githubusercontent.com/pystiche/pystiche/master/docs/source/graphics/banner/banner.jpg
+    :alt: style_transfer_example
+
+Lightning Flash :class:`~flash.image.style_transfer.StyleTransfer` and
+:class:`~flash.image.style_transfer.StyleTransferData` internally rely on `pystiche <https://pystiche.org>`_ as
+backend.
+
+------
+
+***
+Fit
+***
+
+First, you would have to import the :class:`~flash.image.style_transfer.StyleTransfer`
+and :class:`~flash.image.style_transfer.StyleTransferData` from Flash.
+
+.. testcode:: style_transfer
+
+    import flash
+    from flash.core.data.utils import download_data
+    from flash.image.style_transfer import StyleTransfer, StyleTransferData
+    import pystiche
+
+
+Then, download some content images and create a :class:`~flash.image.style_transfer.StyleTransferData` DataModule.
+
+.. testcode:: style_transfer
+
+    download_data("https://github.com/zhiqwang/yolov5-rt-stack/releases/download/v0.3.0/coco128.zip", "data/")
+
+    data_module = StyleTransferData.from_folders(train_folder="data/coco128/images", batch_size=4)
+
+
+Select a style image and pass it to the `StyleTransfer` task.
+
+.. testcode:: style_transfer
+
+    style_image = pystiche.demo.images()["paint"].read(size=256)
+
+    model = StyleTransfer(style_image)
+
+Finally, create a Flash :class:`flash.core.trainer.Trainer` and pass it the model and datamodule.
+
+.. testcode:: style_transfer
+
+    trainer = flash.Trainer(max_epochs=2)
+    trainer.fit(model, data_module)
+
+.. testoutput::
+    :hide:
+
+    ...
+
+
+------
+
+*************
+API reference
+*************
+
+StyleTransfer
+-------------
+
+.. autoclass:: flash.image.StyleTransfer
+    :members:
+    :exclude-members: forward
+
+StyleTransferData
+-----------------
+
+.. autoclass:: flash.image.StyleTransferData

flash/core/data/data_pipeline.py

@@ -180,7 +180,8 @@ def _resolve_function_hierarchy(
         if object_type is None:
             object_type = Preprocess
 
-        prefixes = ['']
+        prefixes = []
+
         if stage in (RunningStage.TRAINING, RunningStage.TUNING):
             prefixes += ['train', 'fit']
         elif stage == RunningStage.VALIDATING:
@@ -190,9 +191,11 @@ def _resolve_function_hierarchy(
         elif stage == RunningStage.PREDICTING:
             prefixes += ['predict']
 
+        prefixes += [None]
+
         for prefix in prefixes:
             if cls._is_overriden(function_name, process_obj, object_type, prefix=prefix):
-                return f'{prefix}_{function_name}'
+                return function_name if prefix is None else f'{prefix}_{function_name}'
 
         return function_name
 

flash/core/data/data_source.py

@@ -298,14 +298,10 @@ def generate_dataset(
 
             mock_dataset = typing.cast(AutoDataset, MockDataset())
             with CurrentRunningStageFuncContext(running_stage, "load_data", self):
-                load_data: Callable[[DATA_TYPE, Optional[Any]], Any] = getattr(
-                    self, DataPipeline._resolve_function_hierarchy(
-                        "load_data",
-                        self,
-                        running_stage,
-                        DataSource,
-                    )
+                resolved_func_name = DataPipeline._resolve_function_hierarchy(
+                    "load_data", self, running_stage, DataSource
                 )
+                load_data: Callable[[DATA_TYPE, Optional[Any]], Any] = getattr(self, resolved_func_name)
                 parameters = signature(load_data).parameters
                 if len(parameters) > 1 and "dataset" in parameters:  # TODO: This was DATASET_KEY before
                     data = load_data(data, mock_dataset)

flash/core/data/transforms.py

@@ -53,6 +53,11 @@ def forward(self, x: Mapping[str, Any]) -> Mapping[str, Any]:
             return result
         return x
 
+    def __repr__(self):
+        keys = self.keys[0] if len(self.keys) == 1 else self.keys
+        transform = [c for c in self.children()]
+        return f"{self.__class__.__name__}(keys={keys}, transform={transform})"
+
 
 class KorniaParallelTransforms(nn.Sequential):
     """The ``KorniaParallelTransforms`` class is an ``nn.Sequential`` which will apply the given transforms to each

flash/core/utilities/imports.py

@@ -74,10 +74,13 @@ def _compare_version(package: str, op, version) -> bool:
 _PYTORCHVIDEO_AVAILABLE = _module_available("pytorchvideo")
 _MATPLOTLIB_AVAILABLE = _module_available("matplotlib")
 _TRANSFORMERS_AVAILABLE = _module_available("transformers")
+_PYSTICHE_AVAILABLE = _module_available("pystiche")
 
 if Version:
     _TORCHVISION_GREATER_EQUAL_0_9 = _compare_version("torchvision", operator.ge, "0.9.0")
+    _PYSTICHE_GREATER_EQUAL_0_7_2 = _compare_version("pystiche", operator.ge, "0.7.2")
 
+_IMAGE_STLYE_TRANSFER = _PYSTICHE_AVAILABLE
 _TEXT_AVAILABLE = _TRANSFORMERS_AVAILABLE
 _TABULAR_AVAILABLE = _TABNET_AVAILABLE and _PANDAS_AVAILABLE
 _VIDEO_AVAILABLE = _PYTORCHVIDEO_AVAILABLE

flash/image/__init__.py

@@ -3,3 +3,4 @@
 from flash.image.detection import ObjectDetectionData, ObjectDetector
 from flash.image.embedding import ImageEmbedder
 from flash.image.segmentation import SemanticSegmentation, SemanticSegmentationData, SemanticSegmentationPreprocess
+from flash.image.style_transfer import StyleTransfer, StyleTransferData, StyleTransferPreprocess

flash/image/style_transfer/__init__.py

@@ -0,0 +1,3 @@
+from flash.image.style_transfer.backbone import STYLE_TRANSFER_BACKBONES
+from flash.image.style_transfer.data import StyleTransferData, StyleTransferPreprocess
+from flash.image.style_transfer.model import StyleTransfer

flash/image/style_transfer/backbone.py

@@ -0,0 +1,28 @@
+import re
+
+from flash.core.registry import FlashRegistry
+from flash.core.utilities.imports import _PYSTICHE_AVAILABLE
+
+STYLE_TRANSFER_BACKBONES = FlashRegistry("backbones")
+
+__all__ = ["STYLE_TRANSFER_BACKBONES"]
+
+if _PYSTICHE_AVAILABLE:
+
+    from pystiche import enc
+
+    MLE_FN_PATTERN = re.compile(r"^(?P<name>\w+?)_multi_layer_encoder$")
+
+    STYLE_TRANSFER_BACKBONES = FlashRegistry("backbones")
+
+    for mle_fn in dir(enc):
+        match = MLE_FN_PATTERN.match(mle_fn)
+        if not match:
+            continue
+
+        STYLE_TRANSFER_BACKBONES(
+            fn=lambda: (getattr(enc, mle_fn)(), None),
+            name=match.group("name"),
+            namespace="image/style_transfer",
+            package="pystiche",
+        )

flash/image/style_transfer/data.py

@@ -0,0 +1,127 @@
+import functools
+import pathlib
+from typing import Any, Callable, Dict, Optional, Sequence, Tuple, Union
+
+from torch import nn
+
+from flash.core.data.data_source import DefaultDataKeys, DefaultDataSources
+from flash.core.data.process import Preprocess
+from flash.core.data.transforms import ApplyToKeys
+from flash.core.utilities.imports import _TORCHVISION_AVAILABLE
+from flash.image.classification import ImageClassificationData
+from flash.image.data import ImageNumpyDataSource, ImagePathsDataSource, ImageTensorDataSource
+from flash.image.style_transfer.utils import raise_not_supported
+
+if _TORCHVISION_AVAILABLE:
+    from torchvision import transforms as T
+
+__all__ = ["StyleTransferPreprocess", "StyleTransferData"]
+
+
+def _apply_to_input(default_transforms_fn, keys: Union[Sequence[DefaultDataKeys],
+                                                       DefaultDataKeys]) -> Callable[..., Dict[str, ApplyToKeys]]:
+
+    @functools.wraps(default_transforms_fn)
+    def wrapper(*args: Any, **kwargs: Any) -> Optional[Dict[str, ApplyToKeys]]:
+        default_transforms = default_transforms_fn(*args, **kwargs)
+        if not default_transforms:
+            return default_transforms
+
+        return {hook: ApplyToKeys(keys, transform) for hook, transform in default_transforms.items()}
+
+    return wrapper
+
+
+class StyleTransferPreprocess(Preprocess):
+
+    def __init__(
+        self,
+        train_transform: Optional[Union[Dict[str, Callable]]] = None,
+        val_transform: Optional[Union[Dict[str, Callable]]] = None,
+        test_transform: Optional[Union[Dict[str, Callable]]] = None,
+        predict_transform: Optional[Union[Dict[str, Callable]]] = None,
+        image_size: int = 256,
+    ):
+        if val_transform:
+            raise_not_supported("validation")
+        if test_transform:
+            raise_not_supported("test")
+
+        if isinstance(image_size, int):
+            image_size = (image_size, image_size)
+
+        self.image_size = image_size
+
+        super().__init__(
+            train_transform=train_transform,
+            val_transform=val_transform,
+            test_transform=test_transform,
+            predict_transform=predict_transform,
+            data_sources={
+                DefaultDataSources.FILES: ImagePathsDataSource(),
+                DefaultDataSources.FOLDERS: ImagePathsDataSource(),
+                DefaultDataSources.NUMPY: ImageNumpyDataSource(),
+                DefaultDataSources.TENSORS: ImageTensorDataSource(),
+                DefaultDataSources.TENSORS: ImageTensorDataSource(),
+            },
+            default_data_source=DefaultDataSources.FILES,
+        )
+
+    def get_state_dict(self) -> Dict[str, Any]:
+        return {**self.transforms, "image_size": self.image_size}
+
+    @classmethod
+    def load_state_dict(cls, state_dict: Dict[str, Any], strict: bool = False):
+        return cls(**state_dict)
+
+    @functools.partial(_apply_to_input, keys=DefaultDataKeys.INPUT)
+    def default_transforms(self) -> Optional[Dict[str, Callable]]:
+        if self.training:
+            return dict(
+                to_tensor_transform=T.ToTensor(),
+                per_sample_transform_on_device=nn.Sequential(
+                    T.Resize(self.image_size),
+                    T.CenterCrop(self.image_size),
+                ),
+            )
+        elif self.predicting:
+            return dict(
+                pre_tensor_transform=T.Resize(self.image_size),
+                to_tensor_transform=T.ToTensor(),
+            )
+        # Style transfer doesn't support a validation or test phase, so we return nothing here
+        return None
+
+
+class StyleTransferData(ImageClassificationData):
+    preprocess_cls = StyleTransferPreprocess
+
+    @classmethod
+    def from_folders(
+        cls,
+        train_folder: Optional[Union[str, pathlib.Path]] = None,
+        predict_folder: Optional[Union[str, pathlib.Path]] = None,
+        train_transform: Optional[Union[str, Dict]] = None,
+        predict_transform: Optional[Union[str, Dict]] = None,
+        preprocess: Optional[Preprocess] = None,
+        **kwargs: Any,
+    ) -> "StyleTransferData":
+
+        if any(param in kwargs for param in ("val_folder", "val_transform")):
+            raise_not_supported("validation")
+
+        if any(param in kwargs for param in ("test_folder", "test_transform")):
+            raise_not_supported("test")
+
+        preprocess = preprocess or cls.preprocess_cls(
+            train_transform=train_transform,
+            predict_transform=predict_transform,
+        )
+
+        return cls.from_data_source(
+            DefaultDataSources.FOLDERS,
+            train_data=train_folder,
+            predict_data=predict_folder,
+            preprocess=preprocess,
+            **kwargs,
+        )