目前数字图像水印研究热点中的可逆数字图像水印,相对于传统图像水印,不仅要求水印可以嵌入到载体图像中,而且要求待嵌入的水印在提取之后,原始载体图像可完整恢复.可逆数字图像水印的这种特性,使得其在医疗、军事、司法等对图像完整性和真实性要求特别高的领域具有广泛的实际应用价值.本文剖析了基于像素对的差值扩展算法、基于矢量的差值扩展算法、基于预测误差调节的可逆水印算法、基于直方图移位的可逆水印算法共4种空域典型可逆水印算法和2种典型的频域可逆水印算法:基于整型DCT系数和直方图修改的可逆水印算法、基于DCT系数量化的可逆水印算法,给出了可逆数字图像水印的嵌入容量评估、视觉质量评估和完整性评价等评价方法.
Currently,reversible digital image watermarking has become a new research hotspot in digital image watermarking.Comparing to traditional digital image watermarking,reversible digital image watermark has higher requirements.It requires that not only watermark can be embedded into image carrier,but also image carrier can be completely recovered after watermark is extracted.This feature of reversible digital image watermarking makes it a wide range of practical value in fields of medical,military,judicial especially for high requirements of image integrity and authenticity.This paper firstly introduces and Analysis four kinds of Typical Reversible Image Watermarking in Spatial Domain including: pixel pair based difference expansion algorithm,pixel vector based difference expansion algorithm,prediction error adjustment algorithm and histogram shifting algorithm,and then gives two kinds of typical reversible image watermarking in frequency domain including: integer DCT and histogram modification algorithm and quantized DCT coefficients algorithm.In the end,this paper gives the performance evaluation criteria of reversible digital image watermarking including: embedding capacity,visual quality and integrity Assessment.