PatchFlow: Leveraging a Flow-Based Model with Patch Features

Die casting plays a crucial role across various industries due to its ability to craft intricate shapes with high precision and smooth surfaces. However, surface defects remain a major issue that impedes die casting quality control. Recently, computer vision techniques have been explored to automate and improve defect detection. In this work, we combine local neighbor-aware patch features with a normalizing flow model and bridge the gap between the generic pretrained feature extractor and industrial product images by introducing an adapter module to increase the efficiency and accuracy of automated anomaly detection. Compared to stateof-the-art methods (Roth et al. 2021), our approach reduces the error rate by 20% on the MVTec AD dataset (Bergmann et al. 2019), achieving an image-level AUROC of 99.28%. Our approach has also enhanced performance on the VisA dataset (Zou et al. 2022), achieving an image-level AUROC of 96.48%. Compared to the state-of-the-art models, this represents a 28.2% reduction in error. Additionally, experiments on a proprietary die casting dataset yield an accuracy of 95.77% for anomaly detection, without requiring any anomalous samples for training. Defect segmentation on MVTecAD dataset is shown in Figure 4. Our method illustrates the potential of leveraging computer vision and deep learning techniques to advance inspection capabilities for the die casting industry.