融合多种不确定性信号,提升对伪造图像的识别能力。
Detection of AI Generated Images Using Combined Uncertainty Measures and Particle Swarm Optimised Rejection Mechanism
- 用三种不确定性度量联合判断图像真伪,增强鲁棒性。
- 在未知生成器上误拒率约70%,有效过滤多数假图。
- 适合需要高安全性的图像审核场景,如媒体验证。
随着AI生成图像日益逼真,区分其与真实图像面临挑战。本文提出一种基于多源不确定性度量的检测框架,结合费舍尔信息(Fisher Information)、蒙特卡洛丢弃法熵、以及深度核学习中高斯过程分类器的预测方差。通过粒子群优化算法学习最优权重并自适应设定拒绝阈值。模型在Stable Diffusion生成图像上训练,评估涵盖GLIDE、VQDM、Midjourney、BigGAN、StyleGAN3等,存在显著分布偏移。标准指标在分布内表现良好,但在分布外性能下降;而联合不确定性方法在未见生成器上实现约70%的误拒率,有效过滤多数被误判的AI样本。尽管对新生成器的正确样本偶有误拒,但此保守策略可支持后续重训练。对自然图像和域内AI数据保持高接受率。面对FGSM和PGD对抗攻击,联合方法拒绝约61%成功攻击,而仅用高斯过程不确定性可达80%。结果表明,多源不确定性融合提供了一种稳健且自适应的AI图像检测方案。
原文摘要 · Abstract (English)
As AI-generated images become increasingly photorealistic, distinguishing them from natural images poses a growing challenge. This paper presents a robust detection framework that leverages multiple uncertainty measures to decide whether to trust or reject a model's predictions. We focus on three complementary techniques: Fisher Information, which captures the sensitivity of model parameters to input variations; entropy-based uncertainty from Monte Carlo Dropout, which reflects predictive variability; and predictive variance from a Deep Kernel Learning framework using a Gaussian Process classifier. To integrate these diverse uncertainty signals, Particle Swarm Optimisation is used to learn optimal weightings and determine an adaptive rejection threshold. The model is trained on Stable Diffusion-generated images and evaluated on GLIDE, VQDM, Midjourney, BigGAN, and StyleGAN3, each introducing significant distribution shifts. While standard metrics such as prediction probability and Fisher-based measures perform well in distribution, their effectiveness degrades under shift. In contrast, the Combined Uncertainty measure consistently achieves an incorrect rejection rate of approximately 70 percent on unseen generators, successfully filtering most misclassified AI samples. Although the system occasionally rejects correct predictions from newer generators, this conservative behaviour is acceptable, as rejected samples can support retraining. The framework maintains high acceptance of accurate predictions for natural images and in-domain AI data. Under adversarial attacks using FGSM and PGD, the Combined Uncertainty method rejects around 61 percent of successful attacks, while GP-based uncertainty alone achieves up to 80 percent. Overall, the results demonstrate that multi-source uncertainty fusion provides a resilient and adaptive solution for AI-generated image detection.
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