Add HD1K dataset for optical flow (#4890)

docs/source/datasets.rst

@@ -45,6 +45,7 @@ You can also create your own datasets using the provided :ref:`base classes <bas
     Flickr30k
     FlyingChairs
     FlyingThings3D
+    HD1K
     HMDB51
     ImageNet
     INaturalist

test/test_datasets.py

@@ -2126,5 +2126,47 @@ class FlyingThings3DTestCase(datasets_utils.ImageDatasetTestCase):
                 pass
 
 
+class HD1KTestCase(KittiFlowTestCase):
+    DATASET_CLASS = datasets.HD1K
+
+    def inject_fake_data(self, tmpdir, config):
+        root = pathlib.Path(tmpdir) / "hd1k"
+
+        num_sequences = 4 if config["split"] == "train" else 3
+        num_examples_per_train_sequence = 3
+
+        for seq_idx in range(num_sequences):
+            # Training data
+            datasets_utils.create_image_folder(
+                root / "hd1k_input",
+                name="image_2",
+                file_name_fn=lambda image_idx: f"{seq_idx:06d}_{image_idx}.png",
+                num_examples=num_examples_per_train_sequence,
+            )
+            datasets_utils.create_image_folder(
+                root / "hd1k_flow_gt",
+                name="flow_occ",
+                file_name_fn=lambda image_idx: f"{seq_idx:06d}_{image_idx}.png",
+                num_examples=num_examples_per_train_sequence,
+            )
+
+            # Test data
+            datasets_utils.create_image_folder(
+                root / "hd1k_challenge",
+                name="image_2",
+                file_name_fn=lambda _: f"{seq_idx:06d}_10.png",
+                num_examples=1,
+            )
+            datasets_utils.create_image_folder(
+                root / "hd1k_challenge",
+                name="image_2",
+                file_name_fn=lambda _: f"{seq_idx:06d}_11.png",
+                num_examples=1,
+            )
+
+        num_examples_per_sequence = num_examples_per_train_sequence if config["split"] == "train" else 2
+        return num_sequences * (num_examples_per_sequence - 1)
+
+
 if __name__ == "__main__":
     unittest.main()

torchvision/datasets/__init__.py

-from ._optical_flow import KittiFlow, Sintel, FlyingChairs, FlyingThings3D
+from ._optical_flow import KittiFlow, Sintel, FlyingChairs, FlyingThings3D, HD1K
 from .caltech import Caltech101, Caltech256
 from .celeba import CelebA
 from .cifar import CIFAR10, CIFAR100
@@ -76,4 +76,5 @@ __all__ = (
     "Sintel",
     "FlyingChairs",
     "FlyingThings3D",
+    "HD1K",
 )

torchvision/datasets/_optical_flow.py

@@ -19,6 +19,7 @@ __all__ = (
     "Sintel",
     "FlyingThings3D",
     "FlyingChairs",
+    "HD1K",
 )
 
 
@@ -363,6 +364,73 @@ class FlyingThings3D(FlowDataset):
         return _read_pfm(file_name)
 
 
+class HD1K(FlowDataset):
+    """`HD1K <http://hci-benchmark.iwr.uni-heidelberg.de/>`__ dataset for optical flow.
+
+    The dataset is expected to have the following structure: ::
+
+        root
+            hd1k
+                hd1k_challenge
+                    image_2
+                hd1k_flow_gt
+                    flow_occ
+                hd1k_input
+                    image_2
+
+    Args:
+        root (string): Root directory of the HD1K Dataset.
+        split (string, optional): The dataset split, either "train" (default) or "test"
+        transforms (callable, optional): A function/transform that takes in
+            ``img1, img2, flow, valid`` and returns a transformed version.
+    """
+
+    _has_builtin_flow_mask = True
+
+    def __init__(self, root, split="train", transforms=None):
+        super().__init__(root=root, transforms=transforms)
+
+        verify_str_arg(split, "split", valid_values=("train", "test"))
+
+        root = Path(root) / "hd1k"
+        if split == "train":
+            # There are 36 "sequences" and we don't want seq i to overlap with seq i + 1, so we need this for loop
+            for seq_idx in range(36):
+                flows = sorted(glob(str(root / "hd1k_flow_gt" / "flow_occ" / f"{seq_idx:06d}_*.png")))
+                images = sorted(glob(str(root / "hd1k_input" / "image_2" / f"{seq_idx:06d}_*.png")))
+                for i in range(len(flows) - 1):
+                    self._flow_list += [flows[i]]
+                    self._image_list += [[images[i], images[i + 1]]]
+        else:
+            images1 = sorted(glob(str(root / "hd1k_challenge" / "image_2" / "*10.png")))
+            images2 = sorted(glob(str(root / "hd1k_challenge" / "image_2" / "*11.png")))
+            for image1, image2 in zip(images1, images2):
+                self._image_list += [[image1, image2]]
+
+        if not self._image_list:
+            raise FileNotFoundError(
+                "Could not find the HD1K images. Please make sure the directory structure is correct."
+            )
+
+    def _read_flow(self, file_name):
+        return _read_16bits_png_with_flow_and_valid_mask(file_name)
+
+    def __getitem__(self, index):
+        """Return example at given index.
+
+        Args:
+            index(int): The index of the example to retrieve
+
+        Returns:
+            tuple: If ``split="train"`` a 4-tuple with ``(img1, img2, flow,
+            valid)`` where ``valid`` is a numpy boolean mask of shape (H, W)
+            indicating which flow values are valid. The flow is a numpy array of
+            shape (2, H, W) and the images are PIL images. If `split="test"`, a
+            4-tuple with ``(img1, img2, None, None)`` is returned.
+        """
+        return super().__getitem__(index)
+
+
 def _read_flo(file_name):
     """Read .flo file in Middlebury format"""
     # Code adapted from: