改进PVO预测的自适应选块可逆图像水印

为了解决预测误差方法在预测精度和图像不可感 知性上的不足,提出一种基于改进PVO的自适应选块可逆图像水印算 法。首先对原始图像进行分块,并利用子块内相关像素不平均值之间的梯度计算子块 噪声级；然后结合像素值排序预测 算子得到预测误差直方图；最后根据子块噪声级自适应地选择水印的嵌入位置,并采用本 文算法进行水印嵌入。本 算法可以根据原始图像的特性自适应选择水印嵌入的子块,提高了像素预测精度,减少了水 印嵌入产生的失真；提取水印信息 后,可以无失真地恢复原始图像。实验结果表明,本文针对噪声级判断以及PVO算法的改进 策略可以有效提升可逆图像水印 算法的性能,在相同的嵌入容量下,本算法嵌入水印后的图像峰值信噪比较相关文献平均提 高了1.3%左右,具有更好的不可感知性。

Adaptive selecting block reversible image watermarking based on improved PVO pre diction

In order to solve the shortcomings of prediction error method in predi ction accuracy and image imperceptibility,an adaptive selecting block reversible image watermarking algo rithm based on improved pixel-value-ordering (PVO) is proposed.Firstly,the original image is divided into blocks,and the noise leve l of the subblock is calculated using the gradient between the correlation pixel and the mean in the subblock.Then,t he prediction error histogram is obtained by combining the PVO prediction operator.Finally, the embedding position of watermarking is adaptively selected according to the noise level of subblock,an d the watermarking is embedded using the improved PVO algorithm.The algorithm can adaptively select the subblo ck of embedding watermarking according to the characteristics of the original image,improves the pixel predi ction accuracy,and reduces the distortion caused by watermarking embedding.After extracting the watermarking i nformation,the original image can be restored without distortion.The experimental results show that the impro ved strategy of the noise level judgment and PVO algorithm in this paper can effectively improve the performan ce of the reversible image watermarking algorithm.Compared with the related references,the peak signal-t o-noise ratio of the watermarked image is improved by about 1.3% on average in the same embedding capacity,and i t has better imperceptibility.