The emergence of powerful image editing software has substantially facilitated digital image tampering, leading to many security issues. Hence, it is urgent to identify tampered images and localize tampered regions. Although much attention has been devoted to image tampering localization in recent years, it is still challenging to perform tampering localization in practical forensic applications. The reasons include the difficulty of learning discriminative representations of tampering traces and the lack of realistic tampered images for training. Since Photoshop is widely used for image tampering in practice, this paper attempts to address the issue of tampering localization by focusing on the detection of commonly used editing tools and operations in Photoshop. In order to well capture tampering traces, a fully convolutional encoder-decoder architecture is designed, where dense connections and dilated convolutions are adopted for achieving better localization performance. In order to effectively train a model in the case of insufficient tampered images, we design a training data generation strategy by resorting to Photoshop scripting, which can imitate human manipulations and generate large-scale training samples. Extensive experimental results show that the proposed approach outperforms state-of-the-art competitors when the model is trained with only generated images or fine-tuned with a small amount of realistic tampered images. The proposed method also has good robustness against some common post-processing operations.
翻译:强大的图像编辑软件的出现大大促进了数字图像的篡改,导致了许多安全问题。因此,迫切需要查明被篡改的图像和对被篡改的区域进行地方化处理。虽然近年来对篡改图像的本地化问题给予了很大关注,但在实际的法医应用中,进行篡改本地化的工作仍然具有挑战性。原因包括难以了解篡改痕迹的歧视性表现和缺乏现实的篡改图像来进行培训。由于摄影店被广泛用于篡改图像的做法,本文试图通过重点探测在摄影店中常用的编辑工具和操作来解决篡改本地化问题。为了捕捉篡改痕迹,我们非常注意设计一个完全的进化的编码破坏器结构,在实际的法医应用中,采用密集的连接和放大的演进来提高本地化绩效。为了在篡改图像不足的情况下有效地培训模型,我们设计了一个培训数据生成战略,采用摄影店的脚本,可以模仿人类的篡改和生成大规模的培训样本。广泛的实验结果显示,为了充分捕捉到篡改的痕迹,设计出一种优于符合现实的图像的模型,因此,还用一种经过训练后制的模型。