Approaching optimal value expansion for reversible watermarking
Approaching optimal value expansion for reversible watermarking
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DOI：
10.1145/1073170.1073188
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发表时间：
2005-08
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影响因子：
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通讯作者：
Bian Yang;M. Schmucker;C. Busch;X. Niu;Shenghe Sun
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文献类型：
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作者：
Bian Yang;M. Schmucker;C. Busch;X. Niu;Shenghe Sun
本文研究了几种最近提出的基于值扩展方案的可逆水印算法：比特移位、直方图修正、扩频、压扩和预测误差扩展，并提出了一个通用的模型--直方图扩展--用于所有基于值扩展的可逆水印算法，它展示了这些不同算法的统一视图，并从这个统一视图给出了它们在水印失真和嵌入容量方面的性能比较。这种直方图扩展的通用模型，可以直接从直方图的值扩展方式来评价和比较不同的值扩展算法的性能。一个更好的值扩展模式从其固有的值扩展结构，这是稳定的不同的输入测试媒体的性能优势，我们从这个一般模型推导出一个公式化的失真估计，这在形式上保证了存在的最佳值扩展方案的特定媒体的水印。在实际应用中，如果计算复杂度允许，可以通过优化方法实现最优值扩展。为了简单起见，我们提出了一个次优但有效的值扩展方案，以接近可逆水印的最佳性能。在本文的后半部分，我们研究了通过改进直方图生成模式，在不同范围内更清晰地分离尺度值的意义上，进一步提高性能的可能性。以上所提出的所有想法都在我们的实验中得到了很好的证明。
We investigate in this paper several recently proposed reversible watermarking algorithms based on value expansion schemes: bit-shifting, histogram modification, spread spectrum, companding and prediction-error expansion, and present a general model - histogram expansion - for all value expansion based reversible watermarking algorithms, which demonstrates a unified view of these different algorithms and gives them a performance comparison in terms of watermarking distortion and embedding capacity from this unified view.With this general model of histogram expansion, performance of different value expansion algorithms can be evaluated and compared directly from their value expansion modes. A better value expansion mode has an advantage in performance from its inherent value expansion structure, which is stable to different input testing media.We deduce from this general model a formulated distortion estimation, which in form guarantees the existence of the optimal value expanding scheme for a specific media to be watermarked. The optimal value expansion can be achieved by optimization methods if the relevant computational complexity is permitted in practical applications. For simplicity, we propose a sub-optimal but efficient value expanding scheme to approach the best performance of reversible watermarking.In the later part of this paper, we investigate the possibility to further increase the performance by improving the histogram generating patterns in the sense of clearer separation of scale values in different ranges. All ideas proposed above are perfectly demonstrated in our experiments.