A high-performance reversible data-hiding scheme for LZW codes

Hiding a message in compression codes can reduce transmission costs and simultaneously make the transmission more secure. In this paper, we propose a high-performance, data-hiding Lempel–Ziv–Welch (HPDH-LZW) scheme, which reversibly embeds data in LZW compression codes by modifying the value of the compression codes, where the value of the LZW code either remains unchanged or is changed to the original value of the LZW code plus the LZW dictionary size according to the data to be embedded. Compared to other information-hiding schemes based on LZW compression codes, the proposed scheme achieves better hiding capacity by increasing the number of symbols available to hide secrets and also achieves faster hiding and extracting speeds due to the lower computation requirements. Our experimental results with the proposed scheme have confirmed both its high embedding capacity and its high speed when hiding and extracting data.     

一种改进的基于LZW压缩编码的可逆信息隐藏算法

针对HPDH-LZW算法在隐藏信息时未能充分利用压缩编码数据空间问题,通过对压缩编码数据空间进行细分,在不同的子空间里隐藏不同数量的秘密信息,实现了一种改进的基于LZW压缩编码的可逆信息隐藏方法。实验表明,与原算法相比,本算法没有增大压缩文件,也没有增加计算复杂度,但具有更大的信息隐藏容量。     

Reversible data hiding in compressed and encrypted images by using Kd-tree

In this paper, a joint scheme and a separable scheme for reversible data hiding (RDH) in compressed and encrypted images by reserving room through Kd-tree were proposed. Firstly, the plain cover image was losslessly compressed and encrypted with lifting based integer wavelet transform (IWT) and set partition in hierarchical tree (SPIHT) encoding. Then, several shift operations were performed on the generated SPIHT bit-stream. The shifted bit-stream was restructured into small chunks and packed in the form of a large square matrix. The binary square matrix was exposed to Kd-tree with random permutations and reserving uniform areas of ones and zeros for secret data hiding. After that, a joint or a separable RDH scheme can be performed in these reserved spaces. In the joint RDH scheme, the secret data were embedded in the reserved spaces before encrypting with multiple chaotic maps. Thus, secret data extraction and cover image recovery were achieved together. In the separable RDH scheme, the secret data were embedded in the reserved spaces after encrypting with multiple chaotic maps. Since message extraction and cover image recovery are performed separately, anyone who has the embedding key can extract the secret message from the marked encrypted copy, while cannot recover the cover image. A complete encoding and decoding procedure of RDH for compressed and encrypted images was elaborated. The imperceptibility analysis showed that the proposed methods bring no distortion to the cover image because there was no change to the original cover image. The experimental results showed that the proposed schemes can perform better for secret data extraction and can restore the original image with 100% reversibility with much more embedding capacity and security. The proposed schemes significantly outperform the state-of-the-art RDH methods in the literature on compressed and encrypted images.

     

Separable reversible data hiding in encrypted images based on scalable blocks

This paper proposes a new separable reversible data hiding method for encrypted images. Proposed scheme employs the pixel redundancy of natural images to construct embedding space. First, cover image is divided into multiple blocks with different scales. According to the pixel average value of each block, the lowest two bits of every pixel are vacated as reserved rooms. Subsequently, the whole image is encrypted by using stream cipher and the secret messages are finally embedded into the reserved rooms by the embedding key. Proposed scheme is separable in the sense that the recipient can achieve different function by the following ways: (a) If the recipient has only decryption key, an approximation plaintext image containing the embedded information can be obtained. (b) If the recipient has only embedded key, secret messages can be extracted correctly. (c) If the recipient has both decryption key and embedded key, he can not only extract the secret messages, but recover the original cover image perfectly. Extensive experiments are performed to show that our proposed schemes outperform existing reversible data hiding schemes in terms of visual quality, embedding capacity and security performance, even if a large-scale image database is used.

     

A novel high payload steganography scheme based on absolute moment block truncation coding

In this paper, we propose an efficient steganography method in the compressed codes of absolute moment block truncation coding (AMBTC). Many recent related schemes focus on implementing reversible data hiding in compressed AMBTC bit stream. However, the reconstructed image of AMBTC is already lossy and the strict reversibility severely limits embedding capacity. Due to the simplicity and regularity of AMBTC codes, implementing irreversible hiding scheme causes very slight loss visual distortion of reconstructed image in exchange of significant improve in embedding capacity. In proposed scheme, smoothness of AMBTC compressed trio is firstly detected, which is then indicated by substituting the LSB of high quantity level with flag bit. For smooth trios, the differences between both quantity levels are firstly encoded by Huffman coding and then concatenated with secret data to generate modified low quantity levels. Meanwhile, all bits in bit planes of smooth trios are substituted with secret data as well. For complex trio, secret bits are only embedded into quantity levels, which is similar to smooth trio except for the differences are encoded by Lloyd-Max quantization. Experimental results indicate that proposed scheme outperforms prior methods both in imperceptivity and embedding capacity, which confirms the effectiveness and superiority of our work.

     

An encoding method for both image compression and data lossless information hiding

Reversible image data hiding technology means the cover image can be totally recovered after the embedded secret data is extracted. In this paper, we propose a reversible image data hiding scheme based on vector quantization (VQ) compressed images. The secret bits are embedded into the VQ index table by modifying the index value according to the difference of neighboring indices. The data hiding capacity and the size of the final codestream (embedded result) are a trade-off, and it can be decided by users. In other words, the proposed scheme has flexible hiding capacity ability. To estimate the performance, the proposed scheme was compared with the scheme proposed by Wang and Lu (2009). The results of the comparison showed that our proposed scheme is superior to the scheme proposed by Wang and Lu in both data hiding capacity and bit rate.     

Extended squared magic matrix for embedding secret information with large payload

Data hiding is a technology designed for safely transmitting secret data through open communication channels, in which the secret data are embedded into a cover carrier imperceptibly. Among the existing data hiding schemes, the exploiting-modification-direction (EMD) based schemes draw considerable attentions due to large embedding capacity. The proposed scheme improves the EMD-2 scheme by constructing an extended squared magic matrix, resulting in a larger embedding capacity high up to 3.15 bits per pixel (bpp). Experimental results show that the proposed scheme outperforms state-of-the-art reference matrix based schemes in terms of embedding capacity, meanwhile, maintains good image quality.

     

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.     

Multilevel reversible data hiding based on histogram modification of difference images

Reversible data hiding has drawn considerable attention in recent years. Reversibility allows original media to be completely recovered from marked media without distortion after embedded message has been extracted. In this paper we propose a multilevel reversible data hiding scheme based on the difference image histogram modification that uses the peak point to hide messages. Through a joint imperceptibility and hiding capacity evaluation, we show that our proposed scheme uses a multilevel hiding strategy to achieve large hiding capacity and keep distortion low. Performance comparisons with other existing reversible hiding schemes are provided to demonstrate the validity of our proposed scheme.     

增强图像平滑度的可逆信息隐藏方案

随着互联网技术的发展和社交网络的普及,可逆信息隐藏技术因其具有无损恢复载体信息的特性而被广泛应用于医疗、军事等领域的隐蔽信息传输。传统的可逆信息隐藏方案大多聚焦于嵌入容量提升和载密图像失真率降低,并未过多关注人们对图像视觉细节的要求,难以抵抗隐藏信息检测方法。针对上述挑战,从增强图像视觉平滑度方面入手,提出了一种增强图像平滑度的可逆信息隐藏方案,在嵌入隐蔽信息的同时提升载密图像最终的视觉质量。具体来说,所提方案将目标图像分为参考区域与非参考区域,利用非参考区域的图像像素预测值与原始像素值的差值作为信息嵌入的判断依据,通过差值平移来嵌入信息;进而构造图像平滑机制,采用高斯滤波作为秘密信息嵌入时像素值修改的模板,对预测值进行滤波计算,将滤波差值无损地加入载体图像中,以达到图像平滑的效果;同时将参考区域的像素值作为边信息,用于实现信息提取方对原始载体图像和秘密信息的无损恢复和提取;并以高斯函数中的滤波系数作为预置秘密信息对嵌入信息进行加密处理以保证嵌入信息的机密性。大量经典图像数据集的测试与分析结果表明,所提方案处理过的载密图像视觉平滑度得到了显著增强,具有较低的失真率、较高的嵌入率和较高的嵌入提取效率。在典型环境下,其生成的载密图像与高斯滤波后的图像相似度可达0.996 3,且可获得37.346的峰值信噪比和0.328 9的嵌入容量。     

Data hiding based on overlapped pixels using hamming code

Most data hiding schemes change the least significant bits to conceal messages in the cover images. Matrix encoding scheme is a well known scheme in this field. The matrix encoding proposed by Crandall can be used in steganographic data hiding methods. Hamming codes are kinds of cover codes. “Hamming + 1” proposed by Zhang et al. is an improved version of matrix encoding steganography. The embedding efficiency of “Hamming + 1” is very high for data hiding, but the embedding rate is low. Our proposed “Hamming + 3” scheme has a slightly reduced embedding efficiency, but improve the embedding rate and image quality. “Hamming + 3” is applied to overlapped blocks, which are composed of 2^k+3 pixels, where k=3. We therefore propose verifying the embedding rate during the embedding and extracting phases. Experimental results show that the reconstructed secret messages are the same as the original secret message, and the proposed scheme exhibits a good embedding rate compared to those of previous schemes.     

A data embedding scheme for color images based on genetic algorithm and absolute moment block truncation coding

Recently, embedding a large amount of secret data into gray-level and color images with low distortion has become an important research issue in steganography. In this paper, we propose a data embedding scheme by using a well-known genetic algorithm, block truncation code and modification direction techniques to embed secret data into compression codes of color images to expand the variety of cover media. In the scheme, the common bitmap generation procedure of GA-AMBTC has been modified to speed up the hiding procedure. Two embedding strategies are proposed to hide secret data into the common bitmap and the quantization values in each block of the cover image. Experimental results confirm that the proposed scheme can provide high data capacity with acceptable image quality of the stego-images. Moreover, the compression ratio of the scheme is exactly the same as that of GA-AMBTC so that attackers cannot detect any trace of hidden data from the size of the modified compressed result.     

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。     

Hiding secret data in images via predictive coding

This paper presents a prediction-based image-hiding scheme that embeds secret data into compression codes during image compression. This scheme employs a two-stage structure: a prediction stage and an entropy coding stage. The secret data is embedded into the difference values of a given image after the prediction stage is performed.According to the experimental results, the image quality is better than Jpeg-Jsteg and its improved scheme (Inform. Sci. 141 (1-2) (2002) 123). The average image quality of the stego-images in the proposed scheme is greater than 50 dB when the hiding capacity is 1 bit per pixel, whereas those values in Jpeg-Jsteg and scheme in Chang et al. (Inform. Sci. 141 (1-2) (2002) 123) are 37.04 and 33.73 dB, respectively. The hiding capacity of the proposed scheme is 65,536 bits when the hiding capacity is 1 bit per pixel, whereas it is 53,248 bits in scheme (Inform. Sci. 141 (1-2) (2002) 123) and less than 3000 bits in Jpeg-Jsteg.     

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.     

High-capacity reversible data hiding in binary images using pattern substitution

Data hiding, as the term itself suggests, means the hiding of secret data in a cover image. The result is a so-called stego-image. Reversible data hiding is technique, where not only the secret data can be extracted from the stego-image, but the cover image can be completely rebuilt after the extraction of secret data. Therefore, reversible data hiding is the choice in cases of secret data hiding, where the recovery of the cover image is required. In this paper, we propose a high-capacity reversible data hiding scheme based on pattern substitution. Our scheme gathers statistical data concerning the occurrence frequencies of various patterns and quantifies the occurrence frequency as it differs from pattern to pattern. In this way, some pattern exchange relationships can be established, and pattern substitution can thus be used for data hiding. In the extraction stage, we reverse these patterns to their original forms and rebuild an undistorted cover image. Our experimental results demonstrate the practicability of the proposed method. In fact, our new scheme gives a better performance than pair-wise logical computation (PWLC) in terms of both hiding capacity and stego-image visual quality.     

一种DCT域稳健的彩色图像隐藏方法*

基于YCbCr色彩系统,提出了一种稳健的DCT域彩色图像隐藏方法,可以将一幅彩色图像隐藏在另一幅公开的彩色载体图像中,并与JPEG压缩标准相兼容。在嵌入过程中,通过对彩色图像各分量值进行合理分配和标志性嵌入,可以有效地克服DCT域秘密图像提取时的严重失真问题;并根据HVS特征和模糊理论对DCT图像块进行模糊分类,实现嵌入强度的自适应变化。实验结果表明,提出的方法对嵌入过程中产生的噪声具有很强的稳健性,恢复的秘密图像的像素值最大失真误差在±1之内,在保证隐秘图像视觉质量的前提下,载体图像具有较大的数据隐藏量。     

Embedding capacity raising in reversible data hiding based on prediction of difference expansion

Most of the proposed methods of reversible data hiding based on difference expansion require location maps to recover cover images. Although the location map can be compressed by a lossless compression algorithm, this lowers embedding capacity and increases computational cost during the procedures of embedding and extracting. The study presents an adaptive reversible data scheme based on the prediction of difference expansion. Since each cover pixel generally resembles its surrounding pixels, most of the difference values between the cover pixels and their corresponding predictive pixels are small; therefore, the proposed scheme gains from embedding capacity by taking full advantage of the large quantities of smaller difference values where secret data can be embedded. The proposed scheme offers several advantages, namely, (1) the location map is no more required, (2) the embedding capacity can be adjusted depending on the practical applications, and (3) the high embedding capacity with minimal visual distortion can be achieved. Moreover, the experimental results demonstrate that the proposed scheme yields high embedding capacity by comparing the related schemes that are proposed recently.     

基于中国剩余定理的高动态图像可逆数据隐藏

针对高动态图像可逆数据隐藏过程中传输安全性与传输效率差的问题,提出基于中国剩余定理的高动态图像可逆数据隐藏方法。依据中国剩余定理及NTICE方法加密和压缩原理,将高动态图像划分单元格,计算各单元格内像素的高4比特位和低4比特位数值,求解两者的同余方程组,对求解得到的两个通解集进行排序。对同步加密和压缩后的高动态图像进行隐秘数据嵌入操作,划分为感兴趣区域和非感兴趣区域,将隐秘数据分为两部分分别嵌入到两个区域中;利用数据提取与图像恢复的过程将隐秘数据嵌入过程逆向操作,实现高动态图像可逆数据隐藏。实验结果表明:嵌入量越大,水印图像与原始高动态图像的相关性越明显,且峰值信噪比波动平稳。     

High-capacity image hiding scheme based on vector quantization

A novel grayscale image hiding scheme that is capable of hiding multiple secret images into a host image of the same size is proposed in this paper. The secret images to be hidden are first compressed by vector quantization with additional index compression process. Then, the compressed secret images are encrypted and embedded into the least-significant bits of the host pixels. To provide good image quality of the stego-image, the modulus function and the image property are employed to hide the secret bits into the host pixels and determine the number of hidden bits in each host pixel, respectively. According to the results, the proposed scheme provides a higher hiding capacity and a higher degree of security than that of the virtual image cryptosystem.