Rethinking the Up-Sampling Operations in CNN-based Generative Network for Generalizable Deepfake Detection
Authors: Chuangchuang Tan, Yao Zhao, Shikui Wei, Guanghua Gu, Ping Liu, Yunchao Wei

Recently the proliferation of highly realistic synthetic images facilitated through a variety of GANs and Diffusions has significantly heightened the susceptibility to misuse. While the primary focus of deepfake detection has traditionally centered on the design of detection algorithms an investigative inquiry into the generator architectures has remained conspicuously absent in recent years. This paper contributes to this lacuna by rethinking the architectures of CNN-based generator thereby establishing a generalized representation of synthetic artifacts. Our findings illuminate that the up-sampling operator can beyond frequency-based artifacts produce generalized forgery artifacts. In particular the local interdependence among image pixels caused by upsampling operators is significantly demonstrated in synthetic images generated by GAN or diffusion. Building upon this observation we introduce the concept of Neighboring Pixel Relationships(NPR) as a means to capture and characterize the generalized structural artifacts stemming from up-sampling operations. A comprehensive analysis is conducted on an open-world dataset comprising samples generated by 28 distinct generative models. This analysis culminates in the establishment of a novel state-of-the-art performance showcasing a remarkable 12.8% improvement over existing methods. The code is available at https://github.com/chuangchuangtan/NPR-DeepfakeDetection.