An image authentication method by applying Hamming code on rearranged bits

In 2007, Chan and Chang proposed an image authentication method using the Hamming code technique. The parity check bits were produced from pixels by using the Hamming code technique, and the produced bits were embedded in other pixels. When recovering, the method had to predict the value of the most-significant bit of each tampered pixel first. Then, the tampered pixel was able to be recovered by referring to the predicted bit and its parity check bits. However, using the most-significant bit is unsuitable because of the risk of making an incorrect prediction. In this paper, the parity check bits are produced from pixels whose bits have been rearranged. This way, the value of the most-significant bit of each tampered pixel can be determined according to its parity check bits. The recovery procedure is also modified to accommodate the rearranging procedure. The experimental results show that the proposed method has a better ability to recover the tampered areas, compared with Chan and Chang’s method. Moreover, the quality of the authenticated images of the proposed method is also higher than that of Chan and Chang’s method.     

A hierarchical digital watermarking method for image tamper detection and recovery

In this paper, we present an efficient and effective digital watermarking method for image tamper detection and recovery. Our method is efficient as it only uses simple operations such as parity check and comparison between average intensities. It is effective because the detection is based on a hierarchical structure so that the accuracy of tamper localization can be ensured. That is, if a tampered block is not detected in level-1 inspection, it will be detected in level-2 or level-3 inspection with a probability of nearly 1. Our method is also very storage effective, as it only requires a secret key and a public chaotic mixing algorithm to recover a tampered image. The experimental results demonstrate that the precision of tamper detection and localization is 99.6% and 100% after level-2 and level-3 inspection, respectively. The tamper recovery rate is better than 93% for a less than half tampered image. As compared with the method in Celik et al. [IEEE Trans. Image Process. 11(6) (2002) 585], our method is not only as simple and as effective in tamper detection and localization, it also provides with the capability of tamper recovery by trading off the quality of the watermarked images about 5 dB.     

An efficient image authentication method based on Hamming code

Image authentication has come through a history of several years. However, up to the present time, most mainstream image authentication schemes are still unable to detect burst bit errors. Moreover, the capability of recovering tampered pixels in detail (complex) areas has not been very satisfactory either. In this paper, we offer to combine the Hamming code technique, Torus automorphism and bit rotation technique to do tamper proofing. According to our experimental results, our new hybrid method can effectively eliminate burst bit errors, and our recovered pixels in detail areas can actually gain very high clarity. The results show that our scheme is quite a practical method, which is quite able to detect and recover tampered areas.     

A public fragile watermarking scheme for 3D model authentication

A public fragile watermarking scheme based on the sensitivity of vertex geometry is proposed for 3D model authentication. In the 3D fragile watermarking embedding, slightly perturbing the positions of a subset of vertices is usually needed to keep them in some predefined relationship with their neighboring vertices. Two problems frequently arise in the embedding stage: the causality problem and the convergence problem. The causality problem arises while the neighboring relationship of a former processed vertex is influenced by the perturbing of its latter processed neighboring vertices. The convergence problem means that the original model has been heavily distorted before some vertices reach the predefined relationship. In this paper, we propose a multi-function vertex embedding method and an adjusting-vertex method to overcome these two problems. The proposed method does not need the original model and watermarks for authentication; moreover, the key for extracting watermarks is relatively smaller than that of previous works. For some artistic or technical models, sometimes it is very important to control the distortion ratio caused by watermark embedding. Our method can control the average distortion by the keys used in watermark embedding. Experimental and analytic results on various kinds of 3D models show the effectiveness of the scheme.     

基于最大意义位(MSB)的图像篡改认证算法

提出一种用于图像认证的半脆弱水印算法,该算法能够区分出恶意攻击和一般的图像处理.实验表明该算法能准确确定篡改的具体位置,同时对JPEG压缩等常规的图像操作具有较好的鲁棒性.这种算法以16×16个像素点为分块单位对图像进行分块认证,通过小波变换并采用SHA-256产生认证信息,再通过颜色量化的方法,把认证水印信息嵌入到图像的最大意义位,在水印的嵌入过程中,以块为单位对认证信息进行置乱后再进行嵌入,保证了认证的可靠性和水印的鲁棒性,有一定的抗攻击能力.     

基于多梯度的区域自适应去马赛克算法*

针对Bayer格式的彩色滤波阵列,鉴于传统去马赛克算法存在图像纹理和边缘模糊的现象,提出了一种基于多梯度的区域自适应去马赛克算法.该算法利用区域水平和垂直方向的梯度组算子来判断区域平滑程度和插值方向,从而有效地恢复绿色分量,同时根据色度差恒定原理来还原另外两个丢失的颜色信息.实验结果显示,相对于传统插值算法提高了图像的峰值信噪比,锐化了图像的纹理和边缘,改善了图像的视觉质量.     

A new data hiding scheme for binary image authentication with small image distortion

A new data hiding scheme for binary image authentication that has a small distortion of the cover image is proposed in this paper. Using the data-embedding algorithm that is based on Hamming codes, the proposed scheme embeds authentication information into the cover image with flipping only a small number of pixels. A special type of the pixels are selected and flipped by a new algorithm to minimize visual distortion. This new algorithm is based on ELSSM (Edge Line Segment Similarity Measure). Randomly shuffling the bit-order of the authentication information to be embedded, the information can only be extracted by the designated receiver who has the symmetric key. We employ two measurement metrics: miss detection rates for the degree of security and PSNR (Peak Signal-to-Noise Ratio) and ELSSM for the degree of the image distortion to demonstrate the feasibility of the proposed scheme. Using these metrics, we analyze the proposed scheme and the previous schemes. The analysis reveals that the proposed scheme requires less image distortion than the previous schemes whilst achieving the same level of the miss detection rate. Experimental results demonstrate that the proposed scheme is more resilient against recent steganalysis attacks than the previous schemes.     

Effective demosaicking algorithm based on edge property for color filter arrays

Under the influence of digitization, digital still cameras (DSC) are becoming prevalent in recent years. The image capturing and file storing process of a digital still camera involves multiple image processing and precise corrective calculations. In order to reduce cost and volume, a digital still camera usually utilizes only one sensor and color filter array (CFA) for capturing images, and reconstructs a corresponding full-color image using a color interpolation method. Demosaicking is the first step of image processing of digital still cameras and has been integrated into the design of a variety of digital still cameras. If noise and blurred edges exist from the onset of image reconstruction, a post-processing can do little to improve the quality of the reconstructed image. A demosaicking method is proposed in this paper to prevent the occurrence of color artifacts. By detecting the edge characteristics of a digital image, accurate weights can be obtained for image interpolation, before refinement is made in post-processing. After comparing the experiment results of this paper with those of previously proposed methods, it is found that the proposed method can effectively reduce color artifacts and enhance image quality.     

Taylor series and adaptive fusion strategy for Bayer demosaicking

Demosaicking is an important step in generating a full-color image from a color filter array image captured by a single-sensor digital camera. In this paper, we propose a new demosaicking algorithm which uses Taylor series and an adaptive fusion strategy. For generating directional predictors, we present a new interpolator based on Taylor series. The directional predictors are used together with spatial and spectral correlations. Using these predictors and the adaptive fusion strategy improves the green channel interpolation, in turn helping to reconstruct the red and blue channel interpolations. Experiments comparing the proposed algorithm to some other demosaicking algorithms show that the proposed algorithm provides superior performance in terms of both objective and subjective image quality.     

Methods for image authentication: a survey

Image authentication techniques have recently gained great attention due to its importance for a large number of multimedia applications. Digital images are increasingly transmitted over non-secure channels such as the Internet. Therefore, military, medical and quality control images must be protected against attempts to manipulate them; such manipulations could tamper the decisions based on these images. To protect the authenticity of multimedia images, several approaches have been proposed. These approaches include conventional cryptography, fragile and semi-fragile watermarking and digital signatures that are based on the image content. The aim of this paper is to present a survey and a comparison of emerging techniques for image authentication. Methods are classified according to the service they provide, that is strict or selective authentication, tamper detection, localization and reconstruction capabilities and robustness against different desired image processing operations. Furthermore, we introduce the concept of image content and discuss the most important requirements for an effective image authentication system design. Different algorithms are described and we focus on their comparison according to the properties cited above.

A numerically stable fragile watermarking scheme for authenticating 3D models

This paper analyzes the numerically instable problem in the current 3D fragile watermarking schemes. Some existing fragile watermarking schemes apply the floating-point arithmetic to embed the watermarks. However, these schemes fail to work properly due to the numerically instable problem, which is common in the floating-point arithmetic. This paper proposes a numerically stable fragile watermarking scheme. The scheme views the mantissa part of the floating-point number as an unsigned integer and operates on it by the bit XOR operator. Since there is no numerical problem in the bit operation, this scheme is numerically stable. The scheme can control the watermark strength through changing the embedding parameters. This paper further discusses selecting appropriate embedding parameters to achieve good performance in terms of the perceptual invisibility and the ability to detect unauthorized attacks on the 3D models. The experimental results show that the proposed public scheme could detect attacks such as adding noise, adding/deleting faces, inserting/removing vertices, etc. The comparisons with the existing fragile schemes show that this scheme is easier to implement and use.     

用于图像认证和窜改检测的稳健图像摘要*

本文提出了一种用于图像认证和篡改检测的稳健图像摘要。该算法利用Zernike矩的幅度和修正后的相位旋转不变性生成图像摘要（图像Hash）。图像Hash之间的相似性用汉明距离度量。仿真结果表明该方法对大部分内容不变的图像操作具有鲁棒性。不同图像对Hash之间的汉明距离远大于阈值,因此该方法可用于图像认证。同时该方法还可以检测图像篡改并可以定位图像篡改的位置。     

一种像素级的图像篡改认证算法

提出了一种用于图像内容像素级篡改认证的脆弱水印算法，能准确识别图像中被篡改的像素点，并且能容忍图像传输过程中出现的个别认证信息位的传输错误。这种算法以向左右和上下各扩展若干个像素点来产生认证信息，结合周围像素来确定嵌入的水印比特而引入基于图像的不确定性的某些算法,常常会出现被篡改的单个像素点不能被准确定位的问题,本算法可有效解决这一问题,认证信息进行加密后再进行嵌入，解决了多数像素级认证算法所出现的安全漏洞问题。     

基于小波域SVD的彩色图像自适应水印方案

提出了一种针对彩色图像认证的半脆弱水印方案,彩色图像亮度信息通过线性变化处理后进行离散小波变换（DWT）,对低频子图分块后进行奇异值分解（SVD）,将置乱后的二值水印信息通过自适应量化嵌入到奇异值中实现内容认证。线性变化处理能改善由水印带来的对彩色图像明暗度的影响,同时利用一维Tent混沌的特性构成混沌二维置换网络,只需要一个初值,使算法更加简单。由实验结果表明该算法对JPEG压缩稳健,而对恶意操作敏感,同时水印提取是盲提取的。     

用于图像认证的数字水印技术综述

随着网络技术和媒体信息数字化的飞速发展,用于图像认证的数字水印技术成为目前研究的热点。主要阐述了当前用于认证的数字图像水印技术的特征、认证系统框架,详细讨论了脆弱水印和半脆弱水印的算法和研究现状,并对认证数字水印技术的未来发展方向进行了展望。     

一种基于视觉特性的图像哈希认证方案*

为了使图像哈希具有更好的鲁棒性和安全性,在脊波域中提出了一种新的基于视觉特性的图像哈希方法。该方法首先将原始图像预处理,然后利用人类视觉特性提取脊波变换域上的系数,最后量化并压缩生成最终哈希值。实验结果表明,该方法能够抵抗JPEG压缩、滤波、加噪声、裁剪和旋转等攻击,且能够区分恶意窜改。生成的哈希值具有很好的鲁棒性和安全性。     

Bayer阵列图像去马赛克算法综述

Bayer阵列图像去马赛克技术是对稀疏采样的Bayer阵列图像进行RGB信息重建,图像重建质量是成像设备评价的重要因素之一,同时也对其他计算机视觉任务(如图像分割、人脸识别)产生影响。随着深度学习方法的快速发展,图像去马赛克领域提出了多种高性能算法。为了便于研究者更全面了解图像去马赛克算法的原理和研究进展,本文对该领域的经典算法和深度学习算法进行综述。首先对Bayer采样阵列原理和图像去马赛克技术进行概述。然后将现有方法分为传统方法和基于深度学习方法两类进行总结,同时根据去马赛克任务是否具有独立性,将深度学习方法分为独立去马赛克任务和联合去马赛克任务两类,分析不同方法的原理和优缺点,重点阐述基于深度学习的去马赛克方法的网络结构和重建机理,介绍去马赛克领域常用的公共数据集和性能评价指标,并对图像去马赛克相关实验进行分析对比。最后,围绕网络深度、运算效率和实用性等方面分析了现阶段图像去马赛克技术面临的挑战及未来发展方向。目前,基于深度学习的图像去马赛克方法已成为主流发展方向,但仍然存在计算成本较高、实际应用性不强等问题。因此,如何开发出重建精度高、处理时间短以及实用性强的图像去马赛克方法,...     

A content-based image authentication scheme based on singular value decomposition

In this paper, we propose an image authentication scheme in which image features are embedded for copyright protection and content-tampering detection. The features are based on the invariance of the relationship among SVD coefficients. The proposed method is sensitive to malicious manipulations and robust to lossy compressions or regular image operations, such as brightening, shifting, averaging, rotation, and so on. Several experiments demonstrated that the proposed scheme could efficiently detect locations which have been tampered with and effectively resist several types of attacks. Moreover, stego images based on our proposed method have high visual quality. The text was submitted by the authors in English. Tzu-Chuen Lu received the B.M. degree (1999) and MSIM degree (2001) in information management from Chaoyang University of Technology, Taiwan. She received her Ph.D. degree (2006) in computer engineering from National Chung Cheng University. Her current title is an Assistant Professor in Departament of Information Management from Chaoyang University of Technology. Her current research interests include data mining, image retrieval, image authentication, information hiding, and knowledge management. Chin-Chen Chang received his B.S. degree in applied mathematics in 1977 and the M.S. degree in computer and decision sciences in 1979, both from the National Tsing Hua University, Hsinchu, Taiwan. He received his Ph.D. in computer engineering in 1982 from the National Chiao Tung University, Hsinchu, Taiwan. From August 1995 to October 1997, he was the provost at the National Chung Cheng University. From September 1996 to October 1997, Dr. Chang was the Acting President at the Nationa Chung Cheng University. From July 1998 to June 2000, he was a director of the Ministry of Education of China. In addition, he has served as a consultant to several research institutes and government departments. His current research interests include database design, computer cryptography, image compression and data structures. Yi-Long Liu received the B.S. degree (2002) in the Department of Mathematics (Applied Mathematics Section) from the College of Science and Engineering at Fu-Jen Catholic University, Taiwan. Liu is now a Master student in National Chung Cheng University and is studying in the domain of image processing. His current research interests include data hiding, data compression, and progressive image transmission.     

Universal demosaicking for imaging pipelines with an RGB color filter array

A universal demosaicking solution appropriate for imaging pipelines employing a red-green-blue (RGB) color filter array (CFA) is introduced. The proposed solution can demosaick a raw, grayscale, CFA sensor image captured by a digital camera equipped with any RGB-CFA currently in use. The solution utilizes a spectral model, an edge-sensing mechanism, and a postprocessor to preserve the coloration and sharpness of the captured image. The framework readably unifies existing demosaicking solutions which differ in design characteristics, performance, and computational efficiency. Simulation studies indicate that the universal demosaicking framework allows for cost-effective camera image processing and produces visually pleasing full-color digital images.     

一种改进的即时消息传递系统认证方案

即时消息传递（IM—Instant messaging）是Internet上日渐普及的一种通信方法。在介绍IM系统工作方式的基础上,详。细分析了当前IM系统在认证方案上的不足以及由此引起的潜在安全威胁。结合数据摘要技术和一次性口令认证方法,对IM系统层对层文件传输提出了一种改进的系统认证方案。该方案面向企业级应用,能够满足安全性要求较高的领域。