The rapid advances in generative AI models have empowered the creation of highly realistic images with arbitrary content, raising concerns about potential misuse and harm, such as Deepfakes. Current research focuses on training detectors using large datasets of generated images. However, these training-based solutions are often computationally expensive and show limited generalization to unseen generated images. In this paper, we propose a training-free method to distinguish between real and AI-generated images. We first observe that real images are more robust to tiny noise perturbations than AI-generated images in the representation space of vision foundation models. Based on this observation, we propose RIGID, a training-free and model-agnostic method for robust AI-generated image detection. RIGID is a simple yet effective approach that identifies whether an image is AI-generated by comparing the representation similarity between the original and the noise-perturbed counterpart. Our evaluation on a diverse set of AI-generated images and benchmarks shows that RIGID significantly outperforms existing trainingbased and training-free detectors. In particular, the average performance of RIGID exceeds the current best training-free method by more than 25%. Importantly, RIGID exhibits strong generalization across different image generation methods and robustness to image corruptions.

该研究提出了一种无需训练的方法（RIGID），通过在视觉基础模型的表示空间中比较原始图像和受到微小噪声扰动的图像之间的相似性，来区分真实图像和由人工智能生成的图像。评估结果显示，RIGID在各种人工智能生成图像和评估指标上明显优于现有的基于训练和无训练的检测器，尤其是性能平均提高了25％以上。此外，RIGID具有很强的泛化能力，适用于不同的图像生成方法，并对图像的损坏具有鲁棒性。

RIGID: 一个面向鲁棒的、无需训练的、模型无关的 AI 生成图片检测框架