图像视频中ENF信号的分析及应用综述

Survey on Analysis and Applications of Electric Network Frequency(ENF) Signals in Image and Video

多媒体录制设备在交流电场或交流电器设备环境中录制视频、图像或音频时,会同时记录电网频率的波动.电网频率(electric network frequency,ENF)具有实时性、连续性以及同电网一致性等特点.因此从这些录制的多媒体文件中估计出的ENF信号是一种很好的时间戳,可用于信息源检测、操作取证及媒体同步等任务.尽管音频、图像和视频中ENF信号存在的形式截然不同,但检测和估计的思路是一致的,部分处理手段是通用的.目前,ENF信号在音频这一载体的研究中已经积累了一些成果,而在图像视频分析中的研究还处于起步阶段.为了更全面地了解图像和视频中ENF信号的特点、估计方法及在信息取证等方面的应用,对相关研究成果进行了梳理总结.首先通过分析图像视频捕获过程来探究ENF信号的形成机理与特点,然后对ENF信号检测和估计中存在的问题及相关方法进行了总结分析,最后介绍了图像视频ENF信号在信息取证方面的应用并指出未来可能的研究方向.

Under the circumstance of alternate current(AC)electric field or around AC electrical equipment,multimedia recording equipment can capture the frequency fluctuation of electric networks simultaneously as it records video,image or audio programs.Electric network frequency(ENF)has the characteristics of realtime,continuity and consistency with surrounding electric networks,thus,the ENF information estimated from these multimedia files can be used for time stamping,information source detection,operation forensics,and media synchronization.In spite of different signal formats of ENF in audio,image and video programs,the detection and estimation methods of ENF are similar,and some processing methods are universal.Up to now,plenty of research works have been done on ENF in audio,but the works on ENF in image and video are far more behind.This paper presents a comprehensive review on the relevant researches,including characteristics,estimation and applications of ENF in images and videos.Firstly,the characteristics of ENF signal are explored by analyzing the processes of capturing images and videos.Then,the problems existing in the detection and estimation of ENF signal and corresponding solving approaches are summarized and analyzed.Finally,the applications of ENF in information forensics and the possible research directions in the future are discussed.