关键词: 可逆水印, JND, 元胞自动机变换

Abstract:

A reversible watermarking method using JND and cellular automata transform (CAT) is proposed.Histogram adjustment technique is first adopted to change the grayscale values of the original images in order to prevent the overflow and underflow of pixels during embedding.Then,the original images are decomposed with the integer wavelet transform (IWT) to extract the high frequency sub-bands for embedding.By calculating the just noticeable difference (JND) of each coefficient,the embedding regions and strength can be controlled flexibly.Finally,the watermark image which is encrypted by CAT is embedded into the chosen wavelet coefficients using the spread spectrum technique.Experimental results show that the proposed method greatly improves the invisibility of watermarks while achieving good capacity.

Key words: reversible watermarking;JND;cellular automata transform