📏 Add PRO metric (#508)

* remove cpu warning

* add pro metric test

* remove pylint ignore statements

* fix component labeling bug

* add more tests for pro metric and ccomp labeling

* use kornia for ccomp labeling

* fix aupro tests

* address PR comments

anomalib/utils/metrics/__init__.py

@@ -18,8 +18,9 @@
 from .collection import AnomalibMetricCollection
 from .min_max import MinMax
 from .optimal_f1 import OptimalF1
+from .pro import PRO
 
-__all__ = ["AUROC", "AUPR", "AUPRO", "OptimalF1", "AdaptiveThreshold", "AnomalyScoreDistribution", "MinMax"]
+__all__ = ["AUROC", "AUPR", "AUPRO", "OptimalF1", "AdaptiveThreshold", "AnomalyScoreDistribution", "MinMax", "PRO"]
 
 
 def get_metrics(config: Union[ListConfig, DictConfig]) -> Tuple[AnomalibMetricCollection, AnomalibMetricCollection]:

anomalib/utils/metrics/aupro.py

@@ -6,13 +6,17 @@
 from typing import Any, Callable, List, Optional, Tuple
 
 import torch
-from kornia.contrib import connected_components
 from matplotlib.figure import Figure
 from torch import Tensor
 from torchmetrics import Metric
 from torchmetrics.functional import auc, roc
 from torchmetrics.utilities.data import dim_zero_cat
 
+from anomalib.utils.metrics.pro import (
+    connected_components_cpu,
+    connected_components_gpu,
+)
+
 from .plotting_utils import plot_figure
 
 
@@ -80,9 +84,10 @@ def _compute(self) -> Tuple[Tensor, Tensor]:
             )
         target = target.unsqueeze(1)  # kornia expects N1HW format
         target = target.type(torch.float)  # kornia expects FloatTensor
-        cca = connected_components(
-            target, num_iterations=1000
-        )  # Need higher thresholds this to avoid oversegmentation.
+        if target.is_cuda:
+            cca = connected_components_gpu(target)
+        else:
+            cca = connected_components_cpu(target)
 
         preds = preds.flatten()
         cca = cca.flatten()

anomalib/utils/metrics/pro.py

@@ -0,0 +1,112 @@
+"""Implementation of PRO metric based on TorchMetrics."""
+
+# Copyright (C) 2022 Intel Corporation
+# SPDX-License-Identifier: Apache-2.0
+
+from typing import List
+
+import cv2
+import numpy as np
+import torch
+from kornia.contrib import connected_components
+from torch import Tensor
+from torchmetrics import Metric
+from torchmetrics.functional import recall
+from torchmetrics.utilities.data import dim_zero_cat
+
+
+class PRO(Metric):
+    """Per-Region Overlap (PRO) Score."""
+
+    target: List[Tensor]
+    preds: List[Tensor]
+
+    def __init__(self, threshold: float = 0.5, **kwargs) -> None:
+        super().__init__(**kwargs)
+        self.threshold = threshold
+
+        self.add_state("preds", default=[], dist_reduce_fx="cat")
+        self.add_state("target", default=[], dist_reduce_fx="cat")
+
+    def update(self, predictions: Tensor, targets: Tensor) -> None:
+        """Compute the PRO score for the current batch."""
+
+        self.target.append(targets)
+        self.preds.append(predictions)
+
+    def compute(self) -> Tensor:
+        """Compute the macro average of the PRO score across all regions in all batches."""
+        target = dim_zero_cat(self.target)
+        preds = dim_zero_cat(self.preds)
+
+        if target.is_cuda:
+            comps = connected_components_gpu(target.unsqueeze(1))
+        else:
+            comps = connected_components_cpu(target.unsqueeze(1))
+        pro = pro_score(preds, comps, threshold=self.threshold)
+        return pro
+
+
+def pro_score(predictions: Tensor, comps: Tensor, threshold: float = 0.5) -> Tensor:
+    """Calculate the PRO score for a batch of predictions.
+
+    Args:
+        predictions (Tensor): Predicted anomaly masks (Bx1xHxW)
+        comps: (Tensor): Labeled connected components (BxHxW). The components should be labeled from 0 to N
+        threshold (float): When predictions are passed as float, the threshold is used to binarize the predictions.
+
+    Returns:
+        Tensor: Scalar value representing the average PRO score for the input batch.
+    """
+    if predictions.dtype == torch.float:
+        predictions = predictions > threshold
+
+    n_comps = len(comps.unique())
+
+    preds = comps.clone()
+    preds[~predictions] = 0
+    if n_comps == 1:  # only background
+        return torch.Tensor([1.0])
+    pro = recall(preds.flatten(), comps.flatten(), num_classes=n_comps, average="macro", ignore_index=0)
+    return pro
+
+
+def connected_components_gpu(binary_input: Tensor, num_iterations: int = 1000) -> Tensor:
+    """Perform connected component labeling on GPU and remap the labels from 0 to N.
+
+    Args:
+        binary_input (Tensor): Binary input data from which we want to extract connected components (Bx1xHxW)
+        num_iterations (int): Number of iterations used in the connected component computation.
+
+    Returns:
+        Tensor: Components labeled from 0 to N.
+    """
+    components = connected_components(binary_input, num_iterations=num_iterations)
+
+    # remap component values from 0 to N
+    labels = components.unique()
+    for new_label, old_label in enumerate(labels):
+        components[components == old_label] = new_label
+
+    return components.int()
+
+
+def connected_components_cpu(image: Tensor) -> Tensor:
+    """Connected component labeling on CPU.
+
+    Args:
+        image (Tensor): Binary input data from which we want to extract connected components (Bx1xHxW)
+
+    Returns:
+        Tensor: Components labeled from 0 to N.
+    """
+    components = torch.zeros_like(image)
+    label_idx = 1
+    for i, mask in enumerate(image):
+        mask = mask.squeeze().numpy().astype(np.uint8)
+        _, comps = cv2.connectedComponents(mask)
+        # remap component values to make sure every component has a unique value when outputs are concatenated
+        for label in np.unique(comps)[1:]:
+            components[i, 0, ...][np.where(comps == label)] = label_idx
+            label_idx += 1
+    return components.int()

tests/pre_merge/utils/metrics/test_aupro.py

@@ -13,21 +13,17 @@ def pytest_generate_tests(metafunc):
             torch.tensor(
                 [
                     [
-                        [
-                            [0, 0, 0, 1, 0, 0, 0],
-                        ]
-                        * 400,
+                        [0, 0, 0, 1, 0, 0, 0],
                     ]
+                    * 400,
                 ]
             ),
             torch.tensor(
                 [
                     [
-                        [
-                            [0, 1, 0, 1, 0, 1, 0],
-                        ]
-                        * 400,
+                        [0, 1, 0, 1, 0, 1, 0],
                     ]
+                    * 400,
                 ]
             ),
         ]

tests/pre_merge/utils/metrics/test_pro.py

@@ -0,0 +1,80 @@
+import torch
+from torch import Tensor
+from torchvision.transforms import RandomAffine
+
+from anomalib.data.utils import random_2d_perlin
+from anomalib.utils.metrics.pro import (
+    PRO,
+    connected_components_cpu,
+    connected_components_gpu,
+)
+
+
+def test_pro():
+    """Checks if PRO metric computes the (macro) average of the per-region overlap."""
+
+    labels = Tensor(
+        [
+            [
+                [0, 0, 0, 0, 0],
+                [1, 0, 0, 0, 0],
+                [0, 0, 0, 0, 0],
+                [1, 1, 0, 0, 0],
+                [0, 0, 0, 0, 0],
+                [1, 1, 1, 0, 0],
+                [0, 0, 0, 0, 0],
+                [1, 1, 1, 1, 0],
+                [0, 0, 0, 0, 0],
+                [1, 1, 1, 1, 1],
+            ]
+        ]
+    )
+
+    preds = (torch.arange(10) / 10) + 0.05
+    preds = preds.unsqueeze(1).repeat(1, 5).view(1, 1, 10, 5)
+
+    thresholds = [0.0, 0.2, 0.4, 0.6, 0.8, 1.0]
+    targets = [1.0, 0.8, 0.6, 0.4, 0.2, 0.0]
+    for threshold, target in zip(thresholds, targets):
+        pro = PRO(threshold=threshold)
+        pro.update(preds, labels)
+        assert pro.compute() == target
+
+
+def test_device_consistency():
+    """Test if the pro metric yields the same results between cpu and gpu."""
+
+    transform = RandomAffine(5, None, (0.95, 1.05), 5)
+
+    batch = torch.zeros((32, 256, 256))
+    for i in range(batch.shape[0]):
+        batch[i, ...] = random_2d_perlin((256, 256), (torch.tensor(4), torch.tensor(4))) > 0.5
+
+    preds = transform(batch).unsqueeze(1)
+
+    pro_cpu = PRO()
+    pro_gpu = PRO()
+
+    pro_cpu.update(preds.cpu(), batch.cpu())
+    pro_gpu.update(preds.cuda(), batch.cuda())
+
+    assert torch.isclose(pro_cpu.compute(), pro_gpu.compute().cpu())
+
+
+def test_connected_component_labeling():
+    """Tests if the connected component labeling algorithms on cpu and gpu yield the same result."""
+
+    # generate batch of random binary images using perlin noise
+    batch = torch.zeros((32, 1, 256, 256))
+    for i in range(batch.shape[0]):
+        batch[i, ...] = random_2d_perlin((256, 256), (torch.tensor(4), torch.tensor(4))) > 0.5
+
+    # get connected component results on both cpu and gpu
+    cc_cpu = connected_components_cpu(batch.cpu())
+    cc_gpu = connected_components_gpu(batch.cuda())
+
+    # check if comps are ordered from 0 to N
+    assert len(cc_cpu.unique()) == cc_cpu.unique().max() + 1
+    assert len(cc_gpu.unique()) == cc_gpu.unique().max() + 1
+    # check if same number of comps found between cpu and gpu
+    assert len(cc_cpu.unique()) == len(cc_gpu.unique())