Fooling human detectors via robust and visually natural adversarial patches

DNNs are vulnerable to adversarial attacks. Physical attacks alter local regions of images by either physically equipping crafted objects or synthesizing adversarial patches. This design is applicable to real-world image capturing scenarios. Currently, adversarial patches are typically generated from random noise. Their textures are different from image textures. Also, these patches are developed without focusing on the relationship between human poses and adversarial robustness. The unnatural pose and texture make patches noticeable in practice. In this work, we propose to synthesize adversarial patches which are visually natural from the perspectives of both poses and textures. In order to adapt adversarial patches to human pose, we propose a patch adaption network PosePatch for patch synthesis, which is guided by perspective transform with estimated human poses. Meanwhile, we develop a network StylePatch to generate harmonized textures for adversarial patches. These networks are combined together for end-to-end training. As a result, our method can synthesize adversarial patches for arbitrary human images without knowing poses and localization in advance. Experiments on benchmark datasets and real-world scenarios show that our method is robust to human pose variations and synthesized adversarial patches are effective, and a user study is made to validate the naturalness.