A novel lossless data hiding scheme based on a combination of prediction and the prediction-error adjustment (PEA) is presented in this paper. For one pixel,its four surrounding neighboring pixels are used to predict it and 1-bit watermark information is embedded into the prediction-error. In traditional approaches,for the purpose of controlling embedding distortion,only pixels with small prediction-errors are used for embedding. However,when the threshold is small,it is difficult to efficiently com-press the location map which is used to identify embedding locations. Thus,PEA is introduced to make large prediction-error available for embedding while causing low embedding distortions,and accord-ingly,the location map can be compressed well. As a result,the hiding capacity is largely increased. A series of experiments are conducted to verify the effectiveness and advantages of the proposed ap-proach.
几何攻击会给数字水印带来同步误差和插值误差,现有的多数抗几何攻击的鲁棒水印方法都把焦点集中在同步误差上,对插值误差的研究甚少。介绍了常见的插值算法并指明了插值误差产生的原因,能够实现最佳的嵌入率、嵌入失真以及鲁棒性之间平衡的QIM(quantization index modulation)水印算法,进而分析了插值误差对QIM算法的影响,在此基础上提出了针对插值误差的逐像素点选择QIM水印算法。实验在纹理程度不同的10幅图像上进行。实验证明,提出的水印算法对插值误差的鲁棒性优于原始的QIM水印算法。
