Exploring DCT Coefficient Quantization Effects for Local Tampering Detection

摘要

In this paper, we focus on local image tampering detection. For a JPEG image, the probability distributions of its DCT coefficients will be disturbed by tampering operation. The tampered region and the unchanged region have different distributions, which is an important clue for locating tampering. Based on the assumption of Laplacian distribution of unquantized ac DCT coefficients, these two distributions as well as the size of tampered region can be estimated so that the probability of each DCT block being tampered is obtained. More accurate localization results could be got when we consider the prior knowledge of common tampered regions. We also design three kinds of features that can distinguish truly tampered regions from the false ones to reduce false alarm. For a tampered image which is saved in lossless compressed format, we also propose the specialized approach, which employs the quantization noise of high-frequency DCT coefficient, to improve the tampering localization performance. Extensive experiments on large scale databases prove the effectiveness of our proposed method and demonstrate that our method is suitable for locating tampered regions with different scales.

出版物
IEEE Transactions on Information Forensics and Security
王伟
王伟
副研究员、硕导

主要从事多媒体内容安全、人工智能安全、多模态内容分析与理解等方面的研究工作。

董晶
董晶
研究员、硕导

主要从事多媒体内容安全、人工智能安全、多模态内容分析与理解等方面的研究工作。详情访问:http://cripac.ia.ac.cn/people/jdong

谭铁牛
谭铁牛
研究员,博导

主要从事图像处理、计算机视觉和模式识别等相关领域的研究工作,目前的研究主要集中在生物特征识别、图像视频理解和信息内容安全等三个方向。