HS-based reversible data hiding scheme using median prediction error

Recently, reversible-data-hiding (RDH) scheme has been developed rapidly. In this paper, based on the local distribution of pixels in a block, (30) a histogram shifting (HS) based RDH scheme using median prediction error is proposed to increase the embedding capacity (EC) and decrease the distortion of stego image. First, we scan an original image to form the non-overlapping blocks. Then each block is sorted for locating its median. So, the median is used as the center to embed data into the pixels distributing on both sides of the median pixel in the block. Finally, the receiver can seek the same median of the block for data extraction and the recovery of the original image. Besides, we use the decomposed location message to modify the original pixels with overflow/underflow. (12) As the median is close to the mean value of block, the generated prediction error histogram is sharper than other schemes, which can provide a high capacity and lower distortion. Thus, the EC of the proposed algorithm outperforms that of the other algorithms. Experiments show the proposed scheme can provide a higher embedding rate and lower distortion as it takes advantage of the local correlation in a block.

     

结合层次结构和直方图平移的无损数据隐藏

针对现有基于差值直方图方法利用原始图像结构关系上的不足,提出了一种基于层次结构和差值直方图平移的无损数据隐藏方法RDH-HSDHS。RDH-HSDHS利用原始图像数据块中像素的差值形成直方图,充分利用图像中相邻像素间的相关性嵌入数据,为了进一步利用数据块中的参考像素进行数据嵌入,将参考像素组成新的图像进行下一层水印嵌入,直到当前层的嵌入容量小于解码所需的附加信息的长度或隐秘图像质量小于给定阈值。实验仿真结果表明,RDH-HSDHS能较好利用原始图像的全局和局部特性,在嵌入容量和隐秘图像质量之间达到较好的折中,在隐秘图像质量超过30 dB的同时,嵌入容量大于0.75 bit/pixel。另外,与相似方法的性能比较证明了提出方法的优势。该方法能有效应用于高质量需求的图像载体中进行信息隐藏。     

Reversible data hiding scheme with edge-direction predictor and modulo operation

Since the first histogram shifting technique was proposed by Ni et al., many histogram based data hiding methods were proposed to improve their scheme. One of the methods is using difference value between cover image and prediction image. Another method is using two point pairs and absolute value for improving Ni et al.’s scheme. In this paper, novel reversible data hiding scheme with edge-direction predictor and modulo operation was proposed for improving histogram shifting technique with 3 cases. We considered as much as possible around pixels by using edge-direction predictor with odd and even line embedding Also, we utilize two point pairs and absolute value at the same time by using modulo operation with wrap around. In the experimental results, the proposed scheme shown a good quality image result about 48dB as similar as other schemes and enhanced hiding capacity over 50 % than other schemes.     

基于差值直方图的简单高效可逆信息隐藏方法

提出一种基于图像相邻像素差值直方图的可逆信息隐藏方法,运用该方法同时提高了信息嵌入容量和嵌入信息后的图像质量。首先对原始图像进行分块、扫描并求取差值直方图,然后在分块图像的差值直方图中选取最高的两个峰值点并向两个方向移位来产生空缺用于信息嵌入。算法充分利用了自然图像的相邻相似特性,同时提高了基于直方图的信息隐藏方案的峰值点数目和峰值点高度,从而大大提高信息嵌入容量。此外,算法在信息嵌入前对待嵌入信息的预处理使得在嵌入同样容量的信息时,对载体图像的影响更小,具有更好的嵌入后图像质量。     

A data hiding scheme using the varieties of pixel-value differencing in multimedia images

In this paper, a capacity promoting technique is proposed for embedding data in an image using pixel-value differencing (PVD). The PVD scheme embeds data by changing the difference value between two adjacent pixels so that more data is embedded into two pixels located in the edge area, than in the smooth area. In order to increase the embedding capacity, a new approach is proposed in this paper by searching edge area more flexibly. Instead of processing a pair of pixels at a time as proposed by Wu and Tsai, two pairs of pixels in a block are processed at the same time. In addition, we proposed a pixel-value shifting scheme to further increase the chances for embedding data. Our scheme exploits the edge areas more efficiently, thus leading to an increase in embedding capacity as shown by experimental results compared to Wu and Tsai's method. Also, the embedding result of our scheme passes the Fridrich et al.’s detection. Besides, according to the distribution of difference values, more practical range partitions are suggested for improving capacity.     

Reversible data hiding for high quality images exploiting interpolation and direction order mechanism

Reversible data hiding can restore the original image from the stego image without any distortion after the embedded secret message is exactly extracted. In this paper, a novel, reversible, data hiding scheme for high quality images is proposed in spatial domain. To increase embedding capacity and enhance image quality, the proposed scheme classifies all pixels as wall pixels and non-wall pixels. For wall pixel, the interpolation error is used to embed secret data over the interpolation prediction method. In contrast, the difference value between the non-wall pixel and its parent pixel, which is defined by the direction order, is computed to hide secret data based on the histogram shifting. The experimental results demonstrate that our scheme provides a larger payload and a better image quality than some existing schemes. Moreover, the performance of the proposed scheme is more stable for different images.     

Reversible watermarking method based on asymmetric-histogram shifting of prediction errors

This paper tries to provide a new perspective for the research of reversible watermarking based on histogram shifting of prediction errors. Instead of obtaining one prediction error for the current pixel, we calculate multiple prediction errors by designing a multi-prediction scheme. An asymmetric error histogram is then constructed by selecting the suitable one from these errors. Compared with traditional symmetric histogram, the asymmetric error histogram reduces the amount of shifted pixels, thus improving the watermarked image quality. Moreover, a complementary embedding strategy is proposed by combining the maximum and minimum error histograms. As the two error histograms shift in the opposite directions during the embedding, some watermarked pixels will be restored to their original values, thus the image quality is further improved. Experimental findings also show that the proposed method re-creates watermarked images of higher quality that carry larger embedding capacity compared to conventional symmetric histogram methods, such as Tsai et al.’s and Luo et al.’s works.     

A local variance-controlled reversible data hiding method using prediction and histogram-shifting

The stego image quality produced by the histogram-shifting based reversible data hiding technique is high; however, it often suffers from lower embedding capacity compared to other types of reversible data hiding techniques. In 2009, Tsai et al. solved this problem by exploiting the similarity of neighboring pixels to construct a histogram of prediction errors; data embedding is done by shifting the error histogram. However, Tsai et al.’s method does not fully exploit the correlation of the neighboring pixels. In this paper, a set of basic pixels is employed to improve the prediction accuracy, thereby increasing the payload. To further improve the image quality, a threshold is used to select only low-variance blocks to join the embedding process. According to the experimental results, the proposed method provides a better or comparable stego image quality than Tsai et al.’s method and other existing reversible data hiding methods under the same payload.     

基于非对称直方图平移的可逆信息隐藏算法

利用两个非对称直方图分别向相反方向平移嵌入信息,会产生像素值的补偿还原效应,提出了一种更好的像素值预测方法,生成两个更偏向0值右侧和左侧的非对称预测误差直方图,这样的两个直方图在进行第二层信息嵌入时,会出现更多的像素点恢复到原始图像像素值,减少图像扭曲失真,提高载密图像质量。与传统算法相比,减少了参与直方图修改的像素量,进一步保护了载密图像质量。     

High capacity reversible hiding scheme based on interpolation,difference expansion,and histogram shifting

Difference expansion and histogram shifting methods are two popular hiding strategies that have been widely used in many researches. For example, Hong and Chen developed a reversible hiding method based on interpolation and histogram shifting. The image quality of their scheme is exceptional; however, their scheme needs to keep and transmit two peak points for secret data extraction and pixel recovering. Moreover, the reference pixels in their scheme cannot be used to embed secret data that will decrease the hiding capacity. Therefore, this paper shall propose a reversible hiding method to enhance their scheme. The proposed method applies the difference expansion, histogram shifting and interpolation strategies to conceal secret data in the reference pixels for increasing the hiding payload. Experimental results indicate that the proposed method performs better in terms of hiding capacity than recently developed methods.