关键字 |
| 数字水印，预插入代码，数据隐藏，盲水印。 |
介绍 |
| 嵌入信息以保护各种形式多媒体的合法版权的技术是当今所需要的。数据隐藏技术关注的是如何有效地将一条信息嵌入覆盖媒体数据中以实现安全。数字水印在保护数字产品版权方面具有重要意义。有效的水印技术要求视觉不可感知性和对各种攻击的鲁棒性。为此，一种新的自识别和抗裁剪水印方法提供了嵌入图像的视觉质量。对于嵌入预插入编码方法来标记水印的原始位置，该方法即使在同步裁剪攻击的情况下也能够定位嵌入的水印并检索它。这种盲水印提取方法采用投票机制，在不知道宿主图像的情况下，提取出精确的水印信息并恢复原始的无标记图像。对于恢复原始图像，该方法可以获取主机图像信息，在抵御多种形式攻击的情况下恢复主机图像，从而保护数字产品的版权。该方法基于预插入编码系统，能够正确识别水印序列。水印嵌入涉及两个关键任务，首先是版权保护的验证和载体图像的原始视图的维护。 To protect the copyright of an image, a watermarking mechanism must be robust enough to resist malicious attacks even if the watermarked image has been attacked. Also the watermarked images quality must be good so that it is difficult for an intruder to distinguish between the host image and the embedded one. In addition, the embedded information should not seriously distort the protected image, which may degrade the images quality. At the time of evaluating a watermarking mechanisms performance, we have to concentrate on issues like, robustness, the watermarked images quality, and the restored images quality. |
2文献调查 |
| 为了保证嵌入图像的视觉质量，重要的是要确保嵌入后的主机图像在视觉上与原始图像保持相似。之前c.c.c chang等人和x.u u等人为保持水印图像和恢复图像的质量所做的工作。有两种方案用于恢复未标记的图像，可逆和可移动的方法，由这些科学家。但是可逆方法和可移动方法仍然无法实现复原图像的鲁棒性和质量。因此，有必要实施更好的方案来增强鲁棒性，同时保证对嵌入图像的影响最小。 |
| 点[1]中的Alattar使用了一种非常大容量的算法，该算法基于任意大小向量的差分展开，用于嵌入具有低图像失真的可逆水印。针对彩色图像，提出了一种具有高数据隐藏能力的可逆水印算法。算法会恢复原始图像，隐藏几位。推导了任意长度向量的可逆整数变换及其它避免下溢的条件。为了最大化可以隐藏在图像中的数据量，在颜色组件上应用嵌入算法。实验结果表明，基于空间的四次算法可以在最高信噪比下隐藏最大的有效载荷。还表明可以嵌入到图像中的数据量在很大程度上取决于图像的性质。测试结果还表明，在较高的PSNR下，基于空间四元组的算法性能优于基于空间三元组的算法。这些结果还表明，在颜色分量上应用算法的性能不如在空间上应用算法; hence, cascading cross-color with spatial applications would be useful only when there is a need to hide a large amount of data without regard to the quality of the watermarked image. |
| 在[2]C.C. Chang等人。，presented a lossless and reversible steganography scheme for hiding secret data in each block of quantized discrete cosine transformation (DCT) coefficients in JPEG images. This shows that the two successive zero coefficients of the medium-frequency components in each block are used to hide the secret data. Also it modifies the quantization table to maintain the quality of the image. The results also confirm that the proposed scheme can provide expected acceptable image quality of images and successfully achieve reversibility. DCT is a widely used mechanism for frequency transformation. To extend the variety of cover images and for the sake of repeated usage, they over a lossless data hiding scheme for DCT-based compressed images. Using a modified quantization table and our proposed embedding strategy, the proposed scheme can maintain the image quality of images, with a PSNR value 2.2 times higher than that ordered by a standard quantization table without affecting hiding capacity. The experimental results further demonstrate that the proposed scheme provides images with acceptable image quality and hiding capacity. |
| c.c.c Chang等人，in [3] presented a reversible data hiding scheme based on side match vector quantization (SMVQ) for digitally compressed images. With this method receiver performs two steps to achieve - extract the secret data and reconstruct the original SMVQ compression codes. The results show that the performance of this proposed scheme is better than those of other information hiding schemes for VQ-based and SMVQ-based compressed images. The experimental results also provides effectiveness and reversibility of the proposed scheme. Hiding data in SMVQcompressed codes originally caused a large distortion in stego-images because SMVQ is a low bit-rate compression scheme. To maintain the advantages of SMVQ and make sure the original compression indexes can be successfully reconstructed after secret data are extracted, they hide the secret data in compressed image and achieve reversibility. The original compressed image can be completely reconstructed after hidden secret data extraction, and the original compressed codes can be stored directly and used repeatedly. In addition, the proposed scheme can simply hide or extract the secret data and restore the SMVQ-compressed codes without complex computations. The hidden secret data can also be extracted from the stego-image without referencing the original compressed cover image. So proposed method is superior to that of other VQ or SMVQ-based reversible hiding schemes. |
| M.U. Celik等人。，in [4] presented a novel framework for lossless authentication watermarking enables zero-distortion reconstruction of un-watermarked images upon verification. They presented a new lossless image authentication framework which offers computational efficiency, public/private key support and improved tamper-localization accuracy. The proposed method is flexible and compatible with the existing lossless data embedding and fragile image authentication algorithms. This new framework allows validation of the watermarked images before recovery of the original image. This decreases computational work when verification step fails or the zero-distortion reconstruction is not needed. For authenticated images the integrity of reconstructed image is ensured by uniqueness of the reconstruction procedure. The framework also enables public(-key) authentication without granting access to the perfect original and allows for efficient tamper localization. Also the effectiveness of this method is demonstrated by implementing the scheme using hierarchical image authentication along with lossless generalized-least significant bit data embedding. |
| 在[5]C.C. Chang等人。，proposed a novel watermarking mechanism by utilizing Pair difference correlations upon subsampling and the technique of JND. The simulation results revealed that the new scheme approximated a lossless watermarking scheme. Also the novel scheme resisted various signal processing attacks and geometric transformation attacks; therefore, it can be used to protect the ownership of important watermarked images. Furthermore, the novel method permitted authorized users to extract and restore the watermarked image without the host image. The new scheme confirms the essentials of robustness and restored image fidelity, which are practical for preserving valuable images. |
| 林志远等人。，in [6] presented an effective technique for image authentication which can prevent malicious manipulations but allow JPEG lossy compression. The authentication is based on invariance of relationships between discrete cosine transform coefficients at the same position in separate blocks of an image. These relationships are preserved when discrete cosine transform coefficients are quantized in JPEG compression. This proposed method can distinguish malicious manipulations from JPEG lossy compression regardless of the compression ratio or the number of compression iterations. They described adaptive methods with probabilistic guarantee to handle distortions introduced by various acceptable manipulations. They also present theoretical and experimental results to demonstrate the activeness of the technique. |
| P. Bas等。，in [7] presented a new approach for watermarking of digital images providing robustness to geometrical distortions. A new class of watermarking schemes using the image content is presented. They propose an embedding and detection scheme where the mark is bound with a content descriptor defined by salient points. The embedding process of the signature is done by extracting feature points of the image and performing a Delaunay tessellation on the set of points. The mark is embedded using a classical additive scheme inside each triangle of the tessellation. The detection is performed using correlation properties on the different triangles. The performance of the presented scheme is evaluated after JPEG compression, geometrical attack and transformations. The final results show that the fact that the method is robust to different manipulations. The presented method is robust to the Stir Mark attack, shearing distortion, JPEG compression, and slight global transformations. But drawback of this technique is that the robustness depends on the capacity of feature point detector. |
| 在[8]C.S. Lu等。，proposed a scheme that can resist two famous water- mark estimation-based attacks, which have successfully cracked many existing watermarking schemes. The false negative and false positive analyses are conducted to verify the performance of scheme. A novel watermarking approach, called the non blind embedder, has applied by exploiting the available information of denoising-based watermark prediction. The information obtained using shrinkage-based denoising (soft-thresholding) techniques is easy to control, and, that denoising itself is, in fact, a solution for oblivious watermark detection. The knowledge at the detector side can then be utilized to design a nonblind embedder, which is extremely advantageous over the common blind embedders. The performance of scheme, composed of a non-blind embedder and a blind detector, has also been analyzed regarding false negative and false positive probabilities. |
| 在[9]J. Barr等人。，developed a system which will mitigate the threat posed by the copy attack. They first developed an image signature algorithm which uses highly stable low frequency DCT coefficients to uniquely describe the image. This image signature was then combined with a standard image watermark, and embedded into the original image. If an attacker attempts to remove the watermark from this image and insert it into a new image, the image signature embedded in the watermark will not match the re-calculated image signature of the new image. The watermark also enables geometric synchronization, which allows us to automatically restore the image to its proper rotation, scale, and translation. This process, which in other systems must be performed by hand, is necessary to ensure the re-calculated image signature matches the image signature of the original digital image. |
| Q. Cheng等人。，in [10] presented an investigation on robust optimum detection of multiplicative watermarks. In this the novel optimum detectors for multiplicative watermarks are derived using locally optimum detection for the generalized Gaussian distributions. For sub-band transformed domains such as the discrete cosine transform, discrete wavelet transform, and pyramid transform, a class of generalized correlators is constructed based on the generalized Gaussian distributions. For this, the square-root detector is designed and demonstrated to have near optimal performance for a large set of images and employed as a universally optimal detector or decoder for images and video. The locally most powerful detection method is then extended to DFT domain multiplicative watermarking with magnitudes of coefficients modeled by the Weibull distributions. The another class of detectors is built based on this statistical modeling. The robust optimum detection of multiplicative watermarks can be applied to copyright notification, enforcement, and broadcast monitoring. They applied the robust optimum watermarking detection to combined audio and video watermarking. It can tolerate commonly used audio and video compressions but is sensitive to content changes. It can be applied to audiovisual content authentication in commerce, law, defense, and journalism. |
| 在[11]C.S. Lu等。，proposed a new digital signature scheme which makes use of an images contents to construct a structural digital signature for image authentication. For image authentication, it is desired that the verification method be able to resist content-preserving modifications while being sensitive to content-changing modifications. The characteristic of the SDS is that it can tolerate content-preserving modifications while detecting content-changing modifications. There are many incidental manipulations that bypassed in the proposed scheme. Performance analysis is conducted and experimental results show that the new scheme is indeed superb for image authentication. |
| S. Craver等人在[12]中提出了隐形水印方案解决版权所有权的能力。它们表明，在某些应用中，仅靠当前的水印方案无法解决合法所有权问题。具体来说，它通过提供可以在水印图像上执行的伪造水印方案来攻击现有技术，从而允许多重权利所有权声明。为了防止他们开发的伪造技术，它检查了通过隐形水印解决所有权所必需的属性。介绍和研究了不可见水印技术的可逆性和准可逆性。他们提出了不可逆转的水印方案，并随后给出了对更复杂的攻击无懈可击的技术实例。 |
| 在[13]X.中，You等人提出了一种构造非张量积小波滤波器组的新方法，并将其应用于水印方案设计。根据特殊的对称矩阵构造了新的非张量积小波滤波器组。它克服了张量小波库只能揭示三个方向上的奇点的缺点。基于他们构建的非张量积小波滤波器组，进行了实证研究，证明了非张量积小波滤波器组在揭示图像各个方向奇异性方面的能力。在此基础上，他们提出了一种改进的显著差分水印方案，该方案在鲁棒性和m-感知性方面显示了非张量积小波水印的优越性。所提出的小波滤波器组使水印方案更加灵活，因为有更多的子带和系数适合水印嵌入。实验结果表明，该算法对各种攻击具有较强的鲁棒性。 |
3结论 |
| 我们必须开发一个足够强大的系统，克服现有水印方法的限制，保持嵌入式图像的最高视觉质量，并对各种恶意攻击具有健壮性。 |
四、确认 |
| 衷心感谢审稿人对本文的审阅，为大大提高论文质量提供了投入。 |
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参考文献 |
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