Reproducing INP-Former: Reconstructing Intrinsic Normal Prototypes for Industrial Anomaly Detection

We reproduce the central claims of INP-Former, a reconstruction-based method for multi-class industrial anomaly detection. INP-Former extracts Intrinsic Normal Prototypes (INPs) from each test image and uses them to guide a decoder that reconstructs normal features, without a stored memory bank. Using the authors' released code, we reproduce the reported performance on MVTec AD and VisA and extend the evaluation to MVTec AD 2, where image AUROC with the default settings is 63.4, compared with 99.7 on MVTec AD. On MVTec AD, a five-seed ablation shows that most of the performance comes from the INP mechanism, while the two auxiliary losses add small changes whose direction depends on the metric. A paired comparison with both losses disabled confirms the benefit of INP on MVTec AD 2. The default of six prototypes transfers less well: the plateau beyond four prototypes reproduces on MVTec AD and VisA, but on MVTec AD 2 a single prototype outperforms six in AU-PRO on the public split and on both hidden test splits. We also measure practical trade-offs in resolution, backbone size, training length, and LoRA adaptation, and examine performance by defect size, lighting condition, and a stricter AU-PRO limit. Several conclusions from the original benchmarks, including the default prototype count, do not carry over to harder data. Code: https://github.com/garasnote/Repro-INPFormer