Ultrasonic image anomaly detection faces significant challenges due to limited labeled data, strong structural and random noise, and highly diverse defect manifestations. To overcome these obstacles, we introduce UltraChip, a new large-scale C-scan benchmark containing about 8,000 real-world images from various chip packaging types, each meticulously annotated with pixel-level masks for cracks, holes, and layers. Building on this resource, we present FSGM-Net, a fully unsupervised framework tailored for anomaly detection. FSGM-Net leverages an adaptive Frequency-Spatial feature filtering mechanism: a learnable FFT-Spatial patch filter first suppresses noise and dynamically assigns normality weights to Vision Transformer (ViT) patch features. Subsequently, an Adaptive Gaussian Mixture Model (Ada-GMM) captures the distribution of normal features and guides a deep-shallow multi-scale interaction decoder for accurate, pixel-level anomaly inference. In addition, we propose a filter loss that enforces encoder-filter consistency and entropy-based sparse gating, together with a distributional loss that encourages both feature reconstruction and confident Gaussian mixture modeling. Extensive experiments demonstrate that FSGM-Net not only achieves state-of-the-art results on UltraChip but also exhibits superior cross-domain generalization to MVTec-AD and VisA, while supporting real-time inference on a single GPU. Together, the dataset and framework advance robust, annotation-free ultrasonic NDT in practical applications.
Zhang et al. (Thu,) studied this question.