Test-Time Adaptation for Detecting Image Inpainting Forgeries

The rapid development of deep learning-based image inpainting poses serious challenges to image authenticity. As inpainting methods continue to evolve, the inpainted images exhibit extremely high visual fidelity, presenting recognition difficulties to the forgery detection model due to differences in operational mode and forgery traces among methods. In particular, the detection performance tends to drop significantly in the testing phase when the test samples differ from the training data. To address this issue, we propose a test-time adaptive detection framework for image inpainting forgeries. First, we propose an image gradient-based metric that quantifies model uncertainty and orchestrates the entire adaptation process. Integrating this metric with sample-specific batch normalization (BN) statistics enhances the ability of pretrained models in the inference stage. Second, we introduce a cross-attention module as a side-tuning module, enabling the model to adapt dynamically to reliable test samples without altering the backbone network. To validate the effectiveness of the proposed method, we construct a dataset comprising synthetic images of multiple inpainting methods and design experiments under two scenarios of distributional bias. The results demonstrate that our proposed framework outperforms the existing baseline method, enhancing the adaptability and detection performance of the forgery detection model in dynamic environments.