  Unsupervised pixel-level defective region segmentation is an important task
in image-based anomaly detection for various industrial applications. The
state-of-the-art methods have their own advantages and limitations:
matrix-decomposition-based methods are robust to noise but lack complex
background image modeling capability; representation-based methods are good at
defective region localization but lack accuracy in defective region shape
contour extraction; reconstruction-based methods detected defective region
match well with the ground truth defective region shape contour but are noisy.
To combine the best of both worlds, we present an unsupervised patch
autoencoder based deep image decomposition (PAEDID) method for defective region
segmentation. In the training stage, we learn the common background as a deep
image prior by a patch autoencoder (PAE) network. In the inference stage, we
formulate anomaly detection as an image decomposition problem with the deep
image prior and domain-specific regularizations. By adopting the proposed
approach, the defective regions in the image can be accurately extracted in an
unsupervised fashion. We demonstrate the effectiveness of the PAEDID method in
simulation studies and an industrial dataset in the case study.
