基于三分量预测误差差值扩展的可逆数据隐藏

针对传统差值扩展存在过分修改像素值、须嵌入定位图等缺陷,提出了一种新的彩色图像可逆数据隐藏算法。首先利用色彩分量之间的相关性减小差值,并根据扩展方向和差值的符号,用较小的差值扩展量修改部分色彩分量的像素值,扩展方向由可能产生上溢和下溢的像素数量决定;其次采用单向像素值调整的方法避免像素值溢出,并用少量的调整信息代替定位图,嵌入容量大幅提高;最后改进差值直方图平移技术控制嵌入容量和图像失真。提取端根据临界像素值的顺序定位调整的像素位置,用调整信息恢复调整的像素值,在提取信息的同时可无损地恢复原始图像。实验结果表明,所提出的算法在大幅提高嵌入容量的同时,仍能保持较高的图像质量。     

A high capacity reversible data hiding scheme with edge prediction and difference expansion

To enhance the embedding capacity of a reversible data hiding system, in this paper, a novel multiple-base lossless scheme based on JPEG-LS pixel value prediction and reversible difference expansion will be presented. The proposed scheme employs a pixel value prediction mechanism to decrease the distortion caused by the hiding of the secret data. In general, the prediction error value tends to be much smaller in smooth areas than in edge areas, and more secret data embedded in smooth areas still meets better stego-image quality. The multiple-base notational system, on the other hand, is applied to increase the payload of the image. With the system, the payload of each pixel, determined by the complexity of its neighboring pixels, can be very different. In addition, the cover image processed by the proposed scheme can be fully recovered without any distortion. Experimental results, as shown in this paper, have demonstrated that the proposed method is capable of hiding more secret data while keeping the stego-image quality degradation imperceptible.     

基于预测误差差值扩展和最低有效位替换的可逆数据隐藏

将差值扩展技术应用于彩色图像,提出一种基于预测误差差值扩展和最低有效位（LSB）替换的彩色图像可逆数据隐藏算法。针对传统差值扩展技术存在过分修改像素灰度值、定位图偏大等缺点,首先利用色彩分量间的相关性减小差值,并将差值扩展量分散到两个色彩分量中;其次,改变差值扩展公式以减少不可扩展差值的数量,提高定位图的压缩率,从而增加嵌入容量;最后,运用LSB替换法嵌入数据,将差值扩展与数据嵌入过程分离,嵌入端和提取端均只需进行一次差值扩展,嵌入和提取效率得以提高。提取端在提取信息时可根据需要无损地恢复原始图像。实验结果表明,该算法在提高嵌入容量和图像质量的同时降低了算法复杂度。     

1 bit/pixel嵌入率的差扩展可逆水印方案

提出了一种新的基于差扩展的可逆水印方案,此方案在一次嵌入过程中能实现1bpp的嵌入率。该方法需借助一个位置图来标示在嵌入过程中用于差扩展的像素对位置,对位置图进行无损压缩,并把压缩后的位置图作为嵌入数据的一部份嵌入到原始图像中,因此,通过改变位置图中"0","1"分布从而能高效压缩位置图,最终获得较高的嵌入容量。实验结果证明该方法的性能优于已存可逆水印算法的性能。     

Prediction-based reversible data hiding

For some applications such as satellite and medical images, reversible data hiding is the best solution to provide copyright protection or authentication. Being reversible, the decoder can extract the hidden data and recover the original image without distortion. In this paper, a reversible data hiding scheme based on prediction error expansion is proposed. The predictive value is computed by using various predictors. The secret data is embedded in the cover image by exploiting the expansion of the difference between a pixel and its predictive value. Experimental results show that our method is capable of providing a great embedding capacity without making noticeable distortion. In addition, the proposed scheme is also applicable to various predictors.     

无定位图的预测误差差值扩展可逆数据隐藏*

将Tian差值扩展技术应用于彩色图像中,提出一种利用预测误差差值进行扩展嵌入的彩色图像可逆数据隐藏算法。针对传统差值扩展技术存在过分修改像素灰度值、须嵌入定位图等缺点,首先利用色彩分量间的相关性减小差值,并将差值扩展量分散到两个色彩分量中;其次,对直方图平移技术进行改进,使得同等嵌入率下图像质量达到最佳;最后由两个色彩分量中像素的预测值之和决定可用于扩展嵌入的像素,无须保存溢出定位图,提取端在提取信息时可无损地恢复原始图像。实验结果表明,与其他算法相比,该算法在同等嵌入率下可取得更好的图像质量,算法复杂度     

A high stego-image quality steganographic scheme with reversibility and high payload using multiple embedding strategy

Tian’s method is a breakthrough reversible data embedding scheme with high embedding capacity measured by bits per pixel (bpp) and good visual quality measured by peak signal-to-noise ratio (PSNR). However, the embedding capacity and visual quality of this method can be significantly improved. Thus, we propose a simple reversible steganographic scheme in spatial domain for digital images by using the multiple embedding strategy. The proposed method horizontally and vertically embeds one secret bit into one cover pixel pair. The experimental results show that the proposed reversible steganographic method achieves good visual quality and high embedding capacity. Specifically, with the one-layer embedding, the proposed method can obtain the embedding capacity of more than 0.5 bpp and the PSNR value greater than 54 dB for all test images. Especially, with the five-layer embedding, the proposed method has the embedding capacity of more than 2 bpp and the PSNR value higher than 52 dB for all test images. Therefore, the proposed method surpasses many existing reversible data embedding methods in terms of visual quality and embedding capacity.     

利用像素置换的自适应可逆信息隐藏

目的 像素置换作为一种可逆信息隐藏方式具有良好的抗灰度直方图隐写分析能力,但嵌入容量偏小一直是其缺陷。针对这一问题,提出了一种基于像素置换的自适应可逆信息隐藏算法。方法 首先,与传统2×2像素块结构相比构造了尺寸更小的像素对结构,使得载体图像可以被更稠密地分割,为嵌入容量的提升提供了基数条件。其次,提出适用于该新像素结构的可嵌像素对（EPP）筛选条件,避免嵌入过程引起图像质量大幅下降。之后,根据EPP的灰度趋势差异对其进行自适应预编码,提高Huffman编码压缩比,进一步提升算法嵌入容量。最终,通过像素置换嵌入信息。结果 与2×2像素块结构的非自适应图像隐写算法相比,在同样保证灰度直方图稳定性的情况下该算法的PSNR提高了32%左右,嵌入容量提高了95%以上。其中自适应性对嵌入容量提升的贡献极大。结论 本文算法同时具有抗灰度直方图隐写分析能力与高嵌入容量性的可逆信息隐藏。算法构造了更高效的可嵌单位,并且针对不同载体图像的特点对其可嵌区域进行差异化编码。实验结果表明,本文算法在具有更好的不可见性的同时,嵌入容量得到大幅提升。     

Quadruple Difference Expansion-Based Reversible Data Hiding Method for Digital Images

ABSTRACT

Lossless data hiding is a special type of data hiding technique that guarantees not only the secret data but also the ability of cover media to be reconstructed without any distortion. A latest lossless data hiding technique is proposed by Hong Lin Jin's that is based on hiding only one data bit in the spatial domain in gray-level image. However, this method uses double difference expansion to embed bits which results in a small embedding capacity. For this purpose, we propose an improved algorithm with the potential of increasing the payload capacity and maintaining good image quality. The proposed improved algorithm is characterized by two aspects. First, the proposed improved reversible data hiding scheme is enhanced to exhibit data hiding in color palette images. Second, the embedding level is improved by using quadruple difference expansion to guarantee the embedding of 2-bit data into color images. Experiments of the proposed improved method have been conducted over several well-known test images. The results show that the proposed improved method significantly improves the embedding capacity over Hong Lin Jin's scheme by the range of 15–35% for grayscale images and 20–46% for color images while still maintaining the quality of the stego-images.     

边缘和纹理优先的可逆数据隐藏算法

为了提高加水印图像的感知质量,对基于图像像素预测误差的嵌入算法进行了研究。优先选择了图像的边缘和纹理进行差值扩展嵌入,并结合压缩性非常高的溢出位置图,实现了高视觉质量、大嵌入容量的可逆数据隐藏算法。     

A reversible data hiding scheme using complementary embedding strategy

Obtaining good visual quality and high hiding capacity with reversible data hiding systems is a technically challenging problem. In this paper, we propose a simple reversible data hiding scheme that uses a complementary hiding strategy. The proposed method embeds one secret bit horizontally and vertically into one cover pixel of a grayscale cover image by decreasing odd-valued pixels and increasing even-valued pixels by one. Experimental results show that the hiding capacity measured by bit per pixel (bpp) of the proposed scheme is at least 1.21 bpp with a PSNR (peak signal-to-noise ratio) value greater than 52 dB for all standard test images. Especially in the case of four-layer embedding, the PSNR value of the proposed method is still greater than 51 dB at a hiding capacity of about 5 bpp for all standard test images. In addition, the proposed method is quite simple because it primarily uses additions and subtractions. These results indicate that the proposed scheme is superior to many existing reversible data hiding schemes introduced in the literature.     

A Novel Difference Expansion Transform for Reversible Data Embedding

Reversible data embedding theory has marked a new epoch for data hiding and information security. Being reversible, the original data and the embedded data should be completely restored. Difference expansion transform is a remarkable breakthrough in reversible data-hiding schemes. The difference expansion method achieves high embedding capacity and keeps distortion low. This paper shows that the difference expansion method with the simplified location map and new expandability can achieve more embedding capacity while keeping the distortion at the same level as the original expansion method. Performance of the proposed scheme in this paper is shown to be better than the original difference expansion scheme by Tian and its improved version by Kamstra and Heijmans. This improvement can be possible by exploiting the quasi-Laplace distribution of the difference values.      

矢量地图的无损数据隐藏算法研究

在矢量地图中隐含水印信息,地图数据的质量往往由于水印的嵌入而受到影响。可逆水印技术(又称无损数据隐藏)具有完整恢复载体数据的能力,因而更加适用于矢量地图。基于差值扩大的思想,提出了一种应用于矢量地图的无损数据隐藏算法。算法根据矢量地图对数据精度的特殊要求提出了相应的水印嵌入条件,并通过修改地图中相邻顶点坐标间的差值来嵌入水印信息。水印的提取过程不仅能够得到隐藏信息,而且能够准确无误地恢复原始地图数据。采用两类地图进行实验,实验结果表明,算法在具有较强坐标相关性的地图中具有较高的嵌入容量,并且引入较低的扰动。算法的应用前景包括矢量地图数据的篡改鉴别、元数据格式兼容以及基于矢量地图的隐藏通信。     

基于块参照像素的无损信息隐藏算法

提出一种具有高嵌入容量的图像无损信息隐藏算法。首先将载体图像分成互不重叠的子块,然后在每块中选定一个参照像素,并计算参照像素与块内其它像素的差。在像素差直方图移位产生冗余空间之后,机密信息就可以无损地嵌入到这些冗余空间中。该方法在机密信息提取后可完全恢复载体图像,而且提取机密信息和恢复载体图像不需要除机密信息长度之外的任何信息。实验结果表明了该算法的有效性。     

Reversible data hiding with context modeling,generalized expansion and boundary map

This paper proposes a reversible data hiding scheme with high capacity-distortion efficiency, which embeds data by expanding prediction-errors. Instead of using the MED predictor as did in other schemes, a predictor with context modeling, which refines prediction-errors through an error feedback mechanism, is adopted to work out prediction-errors. The context modeling can significantly sharpen the distribution of prediction-errors, and benefit the embedding capacity and the image quality. To expand prediction-errors, the proposed scheme utilizes a generalized expansion, which enables it to provide capacities larger than 1 bpp (bits per pixel) without resorting to multiple embedding. Besides, a novel boundary map is proposed to record overflow-potential pixels. The boundary map is much shorter compared with either a location map or an overflow map even though it is not compressed. The combination of the context modeling, the generalized expansion and the boundary map makes the overall scheme efficient in pursuing large embedding capacity and high image quality. Experimental results demonstrate that the proposed scheme provides competitive capacity compared with other state-of-the-art schemes when the image quality is kept at the same level.     

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。     

基于分段差值扩展的彩色图像可逆数据隐藏

针对Tian差值扩展技术存在过分修改像素值、定位图较大等缺点,提出一种基于分段差值扩展的彩色图像可逆数据隐藏算法。利用色彩分量之间的相关性减小差值,并将较小的差值扩展量分散到两个色彩分量中,采用分段差值扩展和位平面替换的方法嵌入数据,从而减少不可扩展差值的数量,提高定位图的压缩率,根据差值次低位平面的可改变性定位不可变差值,从而提高嵌入容量。提取端在提取信息后可根据需要无损地恢复原始图像。实验结果表明,该算法在保证图像质量的同时,嵌入容量有较大的提高。     

A reversible data hiding scheme based on the Sudoku technique

Data hiding, also known as information hiding, plays an important role in information security for various purposes. Reversible data hiding is a technique that allows distortion-free recovery of both the cover image and the secret information. In this paper, we propose a new, reversible data hiding scheme that is based on the Sudoku technique and can achieve higher embedding capacity. The proposed scheme allows embedding more secret bits into a pair of pixels while guaranteeing the good quality of the stego-image. The experimental results showed that the proposed scheme obtained higher embedding capacity than some other previous schemes. In addition, our proposed scheme maintained the good visual quality of the stego-image (i.e., PSNR > 46 dB), which outperforms some existing schemes.     

基于自适应MSB与差值预测的大容量密文域可逆信息隐藏算法

为提高密文域可逆信息隐藏（reversible data hiding in encrypted images,RDH-EI）的嵌入容量,提出了一种基于自适应MSB（most significant bit）与差值预测的RDH-EI方案。首先将图像进行分块,然后进行块级加密和置乱以抵抗对于加密图像的分析。在嵌入数据阶段,对于自适应MSB预测的方法进行改进,将没有嵌入数据的块,利用部分块内像素之间差值很小的特点采用自适应差值预测的方法嵌入数据,以块中左上角像素为目标像素,用于预测其他像素从而腾出更多的嵌入空间。实验结果表明,所提方法具有可逆性和可分离性,并且在自适应MSB预测方法的基础上进一步提高了嵌入容量,对于512×512大小的灰度图像,平均嵌入容量提高了大约7 445 bit。     

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。