A study on digital watermark technique based on the phase modulation of sampling lattice and application to still picture

1.抗攻击能力的提高在该方法中，将嵌入的数据作为标准参考信息进行解码时，需要一张原始图片。我们积极利用这一特点，提出了一种用经过数据压缩编码处理的图像代替原始图像作为标准参考信息的新方法。我们使用授权信源编码(即，JPEG)来检验所提出的方法。结果表明，该方法能够准确地改善误码率特性，例如，以Zelda为例，在信噪比下降约01的情况下，约1000个嵌入的数据比特被正确解码，JPEG压缩比为17。DB.2。从译码误码性能的角度出发，对基于相位调制的数据嵌入方法的编码信号处理进行了讨论，比较了JPEG数据压缩对编码信号处理的健壮性。结果表明，与双线性插值法相比，带限插值法和三次样条插值法具有更好的性能。在合谋攻击中的揭露背叛者基于背叛者使用像素值的算术平均值的这种方法检验了最简单的合谋攻击的效果。结果表明，通过嵌入沃尔什函数，新方法可以成功地揭示出他们是谁。基于纠错码和密码学的数字水印技术将编码理论和密码学相结合，提出了一种新的数字图像数据篡改检测技术。证明了纠错码与密码学的有机结合是非常重要的。我们还给出了一个使用RSA密码的新技术的例子。

1. The improvement on the attack resistanceOn this method, an original picture is necessary for decoding embedding data as a standard reference information. We positively utilize this feature and propose a new method in which we use a processed picture by data compression coding instead of the original pictures as the standard reference information. We examine the proposed method with the authorized source coding (that is, JPEG). The results show that the new method can exactly improve error rate characteristic such that, for instance, as "Zelda", approximately 1, 000 embedded data bits are decoded correctly with the JPEG compression ration of 17 under the degradation of the signal-to-noise ratio within approximately 01. dB.2. A note on the encoding and decoding signal processingFrom the viewpoint of decoding error performance, we have discussed the encoding signal processing for the phase modulation based data embedding method by comparing the robustness against the degradation due to the JPEG data compression. As a result, we conclude that the band-limited interpolation and cubic spline interpolation give better performance, compared with the bi-linear interpolation.3. The disclosing betrayers in collusion attackThe effect of the simplest collusion attack with this method, based on the use of the arithmetic mean of pixel values by betrayers is examined. The results show that by embedding the Walsh function, the new method can successfully disclose who they are.4. Digital watermark based on error correcting codes and cryptographyWe propose a new technique which can detect the forgery of the digital image data by applying both coding theory and cryptology. We show that it is important to combine error correcting code with cryptogram in an appropriate way. We also present an example of new techniques that use RSA cryptogram.