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PatchCore

PatchCore#

Towards Total Recall in Industrial Anomaly Detection.

Paper https://arxiv.org/abs/2106.08265.

class anomalib.models.image.patchcore.lightning_model.Patchcore(backbone='wide_resnet50_2', layers=('layer2', 'layer3'), pre_trained=True, coreset_sampling_ratio=0.1, num_neighbors=9)#

Bases: MemoryBankMixin, AnomalyModule

PatchcoreLightning Module to train PatchCore algorithm.

Parameters:

  • backbone (str) – Backbone CNN network Defaults to wide_resnet50_2.

  • layers (list[str]) – Layers to extract features from the backbone CNN Defaults to ["layer2", "layer3"].

  • pre_trained (bool, optional) – Boolean to check whether to use a pre_trained backbone. Defaults to True.

  • coreset_sampling_ratio (float, optional) – Coreset sampling ratio to subsample embedding. Defaults to 0.1.

  • num_neighbors (int, optional) – Number of nearest neighbors. Defaults to 9.

configure_optimizers()#

Configure optimizers.

Returns:

Do not set optimizers by returning None.

Return type:

None

configure_transforms(image_size=None)#

Default transform for Padim.

Return type:

Transform

fit()#

Apply subsampling to the embedding collected from the training set.

Return type:

None

property learning_type: LearningType#

Return the learning type of the model.

Returns:

Learning type of the model.

Return type:

LearningType

property trainer_arguments: dict[str, Any]#

Return Patchcore trainer arguments.

training_step(batch, *args, **kwargs)#

Generate feature embedding of the batch.

Parameters:

  • batch (dict[str, str | torch.Tensor]) – Batch containing image filename, image, label and mask

  • args – Additional arguments.

  • kwargs – Additional keyword arguments.

Returns:

Embedding Vector

Return type:

dict[str, np.ndarray]

validation_step(batch, *args, **kwargs)#

Get batch of anomaly maps from input image batch.

Parameters:

  • batch (dict[str, str | torch.Tensor]) – Batch containing image filename, image, label and mask

  • args – Additional arguments.

  • kwargs – Additional keyword arguments.

Returns:

Image filenames, test images, GT and predicted label/masks

Return type:

dict[str, Any]

PyTorch model for the PatchCore model implementation.

class anomalib.models.image.patchcore.torch_model.PatchcoreModel(layers, backbone='wide_resnet50_2', pre_trained=True, num_neighbors=9)#

Bases: DynamicBufferMixin, Module

Patchcore Module.

Parameters:

  • layers (list[str]) – Layers used for feature extraction

  • backbone (str, optional) – Pre-trained model backbone. Defaults to resnet18.

  • pre_trained (bool, optional) – Boolean to check whether to use a pre_trained backbone. Defaults to True.

  • num_neighbors (int, optional) – Number of nearest neighbors. Defaults to 9.

compute_anomaly_score(patch_scores, locations, embedding)#

Compute Image-Level Anomaly Score.

Parameters:

  • patch_scores (torch.Tensor) – Patch-level anomaly scores

  • locations (Tensor) – Memory bank locations of the nearest neighbor for each patch location

  • embedding (Tensor) – The feature embeddings that generated the patch scores

Returns:

Image-level anomaly scores

Return type:

Tensor

static euclidean_dist(x, y)#

Calculate pair-wise distance between row vectors in x and those in y.

Replaces torch cdist with p=2, as cdist is not properly exported to onnx and openvino format. Resulting matrix is indexed by x vectors in rows and y vectors in columns.

Parameters:

  • x (Tensor) – input tensor 1

  • y (Tensor) – input tensor 2

Return type:

Tensor

Returns:

Matrix of distances between row vectors in x and y.

forward(input_tensor)#

Return Embedding during training, or a tuple of anomaly map and anomaly score during testing.

Steps performed: 1. Get features from a CNN. 2. Generate embedding based on the features. 3. Compute anomaly map in test mode.

Parameters:

input_tensor (torch.Tensor) – Input tensor

Returns:

Embedding for training, anomaly map and anomaly score for testing.

Return type:

Tensor | dict[str, torch.Tensor]

generate_embedding(features)#

Generate embedding from hierarchical feature map.

Parameters:

  • features (dict[str, Tensor]) – Hierarchical feature map from a CNN (ResNet18 or WideResnet)

  • features – dict[str:Tensor]:

Return type:

Tensor

Returns:

Embedding vector

nearest_neighbors(embedding, n_neighbors)#

Nearest Neighbours using brute force method and euclidean norm.

Parameters:

  • embedding (torch.Tensor) – Features to compare the distance with the memory bank.

  • n_neighbors (int) – Number of neighbors to look at

Returns:

Patch scores. Tensor: Locations of the nearest neighbor(s).

Return type:

Tensor

static reshape_embedding(embedding)#

Reshape Embedding.

Reshapes Embedding to the following format:

  • [Batch, Embedding, Patch, Patch] to [Batch*Patch*Patch, Embedding]

Parameters:

embedding (torch.Tensor) – Embedding tensor extracted from CNN features.

Returns:

Reshaped embedding tensor.

Return type:

Tensor

subsample_embedding(embedding, sampling_ratio)#

Subsample embedding based on coreset sampling and store to memory.

Parameters:

  • embedding (np.ndarray) – Embedding tensor from the CNN

  • sampling_ratio (float) – Coreset sampling ratio

Return type:

None

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