基于软成像的数字图像篡改定位取证研究

Compared with the traditional analog camera era, the popularization of digital cameras, the widespread use of imaging processing software, as well as the development of the internet, have reduced the difficulty of making and transmitting tampered images from three aspects of obtaining, editing and transmitting. The facts that forged digital images frequently appearing on the news, the politics, the military, and the judiciary are making a strong impact on the integrity of the society nowadays..This proposal is focusing on the problem of current digital image forensic algorithms, which means the low applicability of the techniques caused by the over-dependence with the image models. Based on the framework of soft-imaging, we prepare to recover and reconstructed the image inherent features introduced by the image piping, which may be destroyed by image tampering. Simulations and approximations will be realized to model the components of digital camera imaging pipeline. Also the effective soft-imaging approach will be studied and proposed. The research of tampering localization in digital image forensics based on the soft-imaging can reduce the dependence between the image model and tampering localization techniques, which means providing technical guarantee and theoretical support of a more practical scenario in digital image forensics.

与传统胶片时代相比，数码相机的普及、图像处理软件的广泛使用以及互联网的发展这三个因素，从图像获取、编辑和传播三个方面降低了篡改伪造数字图像的制作、传播技术门槛。在新闻、政治、军事和司法等各领域频现的伪造数字图像事件，正在强烈冲击着当今社会的诚信体系。.本申请将针对现有数字图像篡改伪造定位研究中，对图像样本过度依赖导致方法和技术适用性低的问题开展研究工作。基于软成像的思想，拟从数码相机成像部件的模拟和逼近角度出发，通过对待取证图像进行典型的软成像操作，恢复和重建由于篡改伪造破坏的数码相机成像部件引入的图像固有特征。研制基于软成像操作的数码照片图像篡改定位取证技术和方法，降低定位取证技术对图像样本的依赖性，为司法意义下更实用的数字图像定位取证提供技术保障和理论支撑。

本项目以数字图像篡改伪造定位为研究背景，针对图像样本过度依赖导致现有方法和技术适用性低的问题，采用理论分析和数字实验相结合的方法，分析数字图像成像机理，对各软/硬件操作对数字图像特性影响进行仿真、统计和性能分析。基于软成像思想，模拟相机内部成像操作，发掘软成像操作下可逆的描述真实图像规律的统计特征，并提出欠定状态下存在拒识类的同源性分析技术对图像篡改区域进行定位。在研究内容上，完成了1）建立对数码相机的硬件和软件算法引入特性的模拟和逼近的一般模型；2）建立对软成像操作可逆的图像特征描述模型；3）提出欠定状态下存在拒识类的图像相机来源鉴别技术及其在篡改伪造定位的应用方法。在研究成果上，发表学术论文11篇，参加国内外学术会议若干次，举办学术会议1次，培养博士研究生2名、硕士研究生10名；在项目成果转化上，成功申请已受理专利1项。在完成原有研究计划的基础上，超额完成项目内容。大量的实验和研究成果表明，本项目对研制司法意义下更实用的低图像样本依赖性的篡改定位取证技术具有重要研究意义和实际应用价值。