Lossless data hiding for absolute moment block truncation coding using histogram modification

This paper presents a lossless data hiding method for an absolute moment block truncation coding (AMBTC) images, which is a compressed grayscale image. It is not easy to hide secret data in an AMBTC-compressed image because it is composed of bit planes. Thus, it is very sensitive to change some pixels. Nevertheless, to improve the hiding capacity, we present an efficient extension of the histogram modification technique by counting the coefficients of the bit planes in each 4 × 4 block. In addition, our proposed scheme has low complexity and achieves a high embedding capacity with the good perceptual quality compared to the prior arts. In an experiment, we verified our proposed data hiding scheme through the comparison with previous methods.     

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.     

Adaptive lossless steganographic scheme with centralized difference expansion

In this paper, a novel adaptive lossless data hiding scheme is presented that is capable of offering greater embedding capacity than the existing schemes. Unlike the fixed hiding capacity each block provides in most of the currently available lossless data hiding approaches, the proposed method utilizes a block-based lossless data embedding algorithm where the quantity of the hidden information each block bears is variable. To both reduce the image distortion and increase the hiding capacity, the payload of each block depends on its cover image complexity. Due to the fact that schemes with difference expansion tend to damage the image quality seriously in the edge areas, in the proposed scheme, smoother areas are chosen to conceal more secret bits. This way, a better balance can be reached between the embedding ratio and the stego-image quality. In addition, when recovered the cover image can came back to its old self to the last bit without any distortion at all. Experimental results, as this paper will show, have demonstrated that the proposed method is capable of hiding more secret data while maintaining imperceptible stego-image quality degradation.     

选择排序的DCT系数对JPEG图像的可逆数据隐藏

JPEG图像压缩算法可以为使用者提供良好的压缩性能,改善图像文件重建质量,在图像和视频处理领域有着广泛的应用价值。 提出了一种可行且有效的对JPEG图像进行可逆信息隐藏的算法。在该算法中,JPEG图像中所有的8×8块中量化的DCT系数重新排列成新的矩阵,纵列为每个块的系数值,横列为同频率下的系数值。对相同频率下的系数进行模拟嵌入比特位,优先选择失真小的频率下的系数嵌入信息,直到嵌入完秘密比特流信息,同时在嵌入秘密信息时根据解码矩阵减少了无效的比特流扩展。实验结果表明,该算法在嵌入同等数量的比特流的情形下能够得到更好的JPEG图像视觉质量和更少的图像比特流扩展。     

A multiple-level visual secret-sharing scheme without image size expansion

In traditional VSS schemes, the size of the share image is substantially expanded since each pixel of the secret image is mapped onto a block consisting of several pixels. In addition, the quality of the reconstructed secret image is normally degraded in contrast, especially for halftone images. This study proposes a VSS scheme that maps a block in a secret image onto one corresponding equal-sized block in each share image without image size expansion. Two types of techniques, including histogram width-equalization and histogram depth-equalization, are proposed to generate the corresponding share blocks containing multiple levels rather than two levels based on the density of black pixels on the blocks for a secret block. In the former technique, the gray-scale image histogram is obtained by uniformly splitting the range of the pixel gray levels in the secret image, while in the latter the buckets are created so that the area of each bucket is roughly constant by containing approximately the same number of pixels. The proposed schemes significantly improve the quality of the reconstructed secret image compared to several previous investigations.     

基于相关性的图像隐写术

根据图像间的相关性,提出一种新的隐写方法。将秘密图像和载体图像进行小波分解,并将秘密图像的小波域分块,对每一块采用多尺度块匹配机制在载体图像的小波域中寻找与其相似的块。根据相似块计算秘密图像小波域的替换图。用零树小波编码方法对替换图编码。将编码信息以及相似块的映射规则等嵌入载体图像的最低有效位。实验结果表明该方法优于相关文献方法。当以典型的F-16飞机图为秘密图像时,用该方法所提取的秘密图像质量至少提高3dB。     

Development of a data hiding scheme based on combination theory for lowering the visual noise in binary images

In order to raise the embedding capacity and simultaneously reduce the artifact effect caused by embedding secret messages into binary images, a novel data hiding method based on the combination theory is proposed. In the proposed scheme, a secret position matrix is designed to improve the hiding capacity which is capable of preventing the least distortion based on the combination theory. Our new scheme enables users to conceal more than one bit of secret data by changing at most one pixel in one subimage. We have derived a formula for computing the payload and the possible modification pixels of a block. Compared with the existing schemes in terms of the hiding capacity and the visual artifacts, as our experimental results show, the proposed scheme is capable of providing a better image quality protector even with a more efficient secret data hider.     

Reversible data hiding based on block median preservation

This paper proposes a reversible data hiding scheme for gray level images. It exploits the high correlation among image block pixels to produce a difference histogram. Secret data is embedded based on a multi-level histogram shifting mechanism with reference to the integer median of each block. The image blocks are divided into four categories due to four corresponding embedding strategies, aiming at preserving the medians during data embedding. In decoder, the median pixels are retrieved first followed by the hidden data extraction, and the host image can be accurately recovered via an inverse histogram shifting mechanism after removing the secret data from the marked image. Experimental results validate the effectiveness of our scheme and demonstrate that it outperforms several previous methods in terms of capacity and marked image’s quality.     

High capacity reversible data hiding scheme based upon discrete cosine transformation

In this paper, we propose a reversible data hiding scheme based on the varieties of coefficients of discrete cosine transformation of an image. Cover images are decomposed into several different frequencies, and the high-frequency parts are embedded with secret data. We use integer mapping to implement our 2-dimensional discrete cosine transformation. Thus, the image recovered from the modified coefficients can be transformed back to the correct data-hidden coefficients. Since the distribution of 2-dimensional DCT coefficients looks close to Gaussian distribution centralized at zero, it is a natural candidate for embedding secret data using the histogram shifting approach. Thus, our approach shifts the positive coefficients around zero to the right and the negative coefficients around zero to the left in order to leave a space to hide the secret data. The experimental comparisons show that, compared to Chang et al. and Lin et al.'s method, the embedding capacity and quality of the stego-image of the proposed method is a great improvement.     

A high quality and small shadow size visual secret sharing scheme based on hybrid strategy for grayscale images

Many secret sharing schemes for digital images have been developed in recent decades. Traditional schemes typically must deal with the problem of computational complexity, and other visual secret sharing schemes come with a higher transmission cost and storage cost; that is, each shadow size is m times as big as the original secret image. The new (2,n) secret sharing scheme for grayscale images proposed in this paper is based a combination of acceptable image quality using block truncation coding (BTC), high compression ratio discrete wavelet transform (DWT) and good subjective performance of the vector quantization (VQ) technique. Experimental results confirm that our proposed scheme not only generates a high quality reconstructed original image but also generates small, random-like grayscale shadows.     

Reversible data hiding based on a modified difference expansion for H.264/AVC video streams

Reversible Data Hiding (RDH), also referred to as invertible or lossless data hiding, has gradually received much attention from the research community in recent years. In this paper, a RDH scheme for H.264/AVC videos is proposed and it is based on a novel way to expand the difference of a pair of Quantized Discrete Cosine Transform (QDCT) coefficients. The secret data is embedded into the QDCT coefficients of 4?×?4 luminance blocks which selected according to two conditions to achieve good visual quality. In every embeddable 4?×?4 blocks each to- be-embedded information bit is embedded into the selected coefficient-pair. All the selected coefficient-pairs are changed by the proposed difference expanding strategy, which causes low distortion on visual quality. Experimental results have demonstrated that the proposed scheme obtains a little degradation of visual quality and keeps the variation low in bit-rate increase.

     

A secret sharing scheme for EBTC using steganography

In this paper, a new method based on Block Truncation Coding (BTC) and the halftoning technique is proposed for secret sharing of lossy compressed images. BTC is a simple and efficient image compression technique. However, it yields images of undesirable quality, and significant blocking effects are seen as the block size that is used increases. A modified method known as Enhanced Block Truncation Coding (EBTC) is proposed to solve these problems. For secret sharing, we propose a (2, 2) secret sharing scheme which provides authentication using DE scheme. This scheme was developed for data hiding with grayscale images, but our proposed EBTC uses bitmap images for which the DE scheme is not appropriate. We show the solution for such a problem. Moreover, we reduce the computation complexity for secret sharing using the DE algorithm because past schemes which used polynomial or interpolation algorithms require too much time for secret sharing. In addition, we show how to authenticate a cover image. Experimental results show that our proposed scheme provides secret sharing with proper authentication and acceptable computational complexity.     

An oblivious fragile watermarking scheme for images utilizing edge transitions in BTC bitmaps

As one of the famous block-based image coding schemes,block truncation coding(BTC) has been also applied in digital watermarking.Previous BTC-based watermarking or hiding schemes usually embed secret data by modifying the BTC encoding stage or BTC-compressed data,obtaining the watermarked image with poorer quality than the BTC-compressed version.This paper presents a new oblivious image watermarking scheme by exploiting BTC bitmaps.Unlike the traditional schemes,our approach does not really perform the BTC compression on images during the embedding process but utilizes the parity of the number of horizontal edge transitions in each BTC bitmap to guide the watermark embedding and extraction processes.The embedding process starts by partitioning the original cover image into non-overlapping 4×4 blocks and performing BTC on each block to obtain its BTC bitmap.One watermark bit is embedded in each block by modifying at most three pixel values in the block to make sure that the parity of the number of horizontal edge transitions in the bitmap of the modified block is equal to the embedded watermark bit.In the extraction stage,the suspicious image is first partitioned into non-overlapping 4×4 blocks and BTC is performed on each block to obtain its bitmap.Then,by checking the parity of the number of horizontal edge transitions in the bitmap,we can extract one watermark bit in each block.Experimental results demonstrate that the proposed watermarking scheme is fragile to various image processing operations while keeping the transparency very well.     

An efficient and secure VoIP communication system with chaotic mapping and message digest

As one of the most popular real-time services on the Internet, Voice over internet protocol (VoIP) has attracted researchers’ attention in the information security field for its characters of real-time and high flow. To protect data security, a new covert VoIP communications system was proposed in this study to realize secure communications by hiding secret information in VoIP streams. In the proposed algorithm, secret data were divided into blocks after being encrypted with a block cipher, and then each block of secret data was embedded into VoIP streaming packets randomly using a chaotic mapping. The symmetric key was distributed through an efficient and secure channel, and the message digest was implemented to protect the integrity of secret data. The experimental data were collected by comparing audio data between the sender and the receiver. The experimental results indicated that data embedding had little impact on the quality of speech. Besides, statistical analysis could not detect the secret data embedded in VoIP streams using the block cipher and random numbers generated from chaotic mapping. The proposed covert VoIP communications system not only achieved high quality of VoIP and prevented detection of statistical analysis, but also provided integrity for secret data.     

Hybrid secret hiding schemes based on absolute moment block truncation coding

This paper presents two secret hiding schemes based on absolute moment block truncation coding (AMBTC). One is for embedding secrets into complex blocks and the other one is for smooth blocks. As for the smooth blocks, the small variation of the block is adopted to define the embedding rule to minimize the distortion after data embedding. As for the complex blocks, the large variation of the block is used to embed more secrets while maintaining good visual quality. In the experiments, when compared to Ou and Sun’s scheme, the positive data is to confirm the higher capacity while preserving better visual quality.     

一种抗统计分析的DCT域信息隐藏方法

本文给出了一种改进的基于DCF域的信息隐藏方法,在一定信息隐藏容量和较好载体图像视觉效果的前提下,能有效地抵抗基于IQM的统计分析方法。该方法把秘密信息隐藏在图像DCT域的低频区域,并对隐藏信息后的DCT系数做伪随机处理,以保持原图像的噪声分布。该方法已在计算机上进行了模拟,获得了较好的效果。     

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.

     

以H.264为载体的隐秘传输方法

提出了一种H.264视频在流媒体环境下的隐秘传输方法。该方法将秘密信息分段备份,用哈希函数置乱分段及备份的嵌入顺序,当秘密信息由于丢帧而损失时,用备份信息来恢复损失的秘密信息。数位信息隐藏算法将信息嵌在I帧的[4×4]子块亮度DCT系数,改变7个中频系数中1个奇偶性嵌入3比特信息。实验表明,该方法在一定丢包率下能有效恢复损失的秘密信息,适合于流媒体应用环境。     

统计量移位的鲁棒无损图像信息隐藏

鲁棒无损信息隐藏在医学成像、法律取证、遥感等领域有广泛的应用。提出了一种鲁棒无损图像信息隐藏算法。在含密载体图像未受损情况下,正确提取秘密信息后可无损恢复原始载体图像;在含密载体图像受到一定程度JPEG2000压缩攻击后,秘密信息仍然可以被正确提取。首先将原始载体图像分块并计算每个图像块的统计量,再根据统计量绝对值的最大值选择合适的阈值对统计量进行移位,最后利用移位后的统计量来嵌入秘密信息。实验结果表明,该算法在图像视觉质量、嵌入容量和鲁棒性3个方面都具有很好的性能。与其他鲁棒无损嵌入方法相比,在图像视觉质量和鲁棒性大致相当的情况下,该算法的嵌入容量有了很大提高,表明该算法较其他算法具有明显的优势。     

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.