Since the COVID-19 outbreak, there has been a growing need for contactless healthcare to meet medical diagnosis demands. Electronic health systems using the Internet of Things (IoT) are rapidly advancing, transmitting significant amounts of private medical data online. In telemedicine, where patients are diagnosed remotely, sensitive information, such as patient records, may be embedded into medical images for security purposes. Due to the large file sizes of medical images produced by equipment, compression is essential for fast transmission. To safeguard medical images in telemedicine and address bandwidth limitations, we utilize data hiding techniques and absolute moment block truncation coding (AMBTC) compression to introduce an IoT-driven electronic health protection mechanism. Our mechanism employs diverse methods to compress and embed data across various image blocks. Additionally, it offers a flexible adaptation to meet different application requirements concerning embedding capacity, visual quality, and file size by adjusting thresholds and variants. Compared to alternative methods, our approach delivers superior payload capacity and efficiency while preserving visual fidelity.

In this paper, we present our design of a new, blind, reversible, robust, watermarking scheme for relational databases storing textual and numerical data, which is not only guaranteed to meet the above seven requirements and to provide proof of ownership for the legal owner of a relational database but also does not require the existence of the primary key attribute in the relational database. Extensive analysis and our experimental results showed that the proposed scheme achieves strong robustness under a variety of possible attacks, e.g., deletion attacks, modification attacks, addition attacks, and sorting attacks. In addition, in comparison with six existing schemes, the proposed scheme was more secure and robust, as evidenced by our experimental results and robustness analysis.

Information hiding is a technique that conceals private information in a trustable carrier, making it imperceptible to unauthorised people. This technique has been used extensively for secure transmissions of multimedia, such as videos, animations, and images. This study proposes a novel Tetris‐based data hiding scheme to flexibly hide more secret messages while ensuring message security. First, an L Q L Q square lattice Q is selected to determine the maximum embedding capacity, and then it is filled without gaps through rotating and sliding tetrominoes while making the shape of each tetromino different. Secondly, according to the decided Q , the reference matrix and corresponding look‐up table are constructed and then used for secret messages embedding and extraction. In the authors approach, each pixel pair of the original image can be processed to conceal 4‐ or 6‐bit secret messages. The experimental results show that their proposed Tetris‐based scheme has excellent performance, exceeding the performance of some state‐of‐the‐art schemes in both embedding capacity and visual quality. The proposed scheme also provides secure covert communication.

In this study, the authors propose a secret image sharing scheme based on code division multiplexing. The secret data are decoded into n host images to generate n meaningful shares using n encoding codes. Any two of encoding codes are orthogonal to each other. If and only if with n shares together, the secret data can be retrieved successfully, and the host images can be recovered completely. The merits of the proposed scheme are summarised as follows: (i) the meaningful shares generated by the proposed scheme can successfully avoid suspicions by malicious attackers during transmission; (ii) the secret data can be losslessly retrieved and the host images can be recovered completely; (iii) the generated shares can be verified so that the forged shares can be detected; (iv) an arbitrary number of shares can be generated to meet the requirement of practical applications; and (v) moreover, n host images can be either identical or different. The experimental results and analyses show that the proposed scheme can provide high security and outperform state‐of‐the‐art secret sharing schemes.

This paper presents a blind dual watermarking mechanism for digital color images in which invisible robust watermarks are embedded for copyright protection and fragile watermarks are embedded for image authentication. For the purpose of copyright protection, the first watermark is embedded using the discrete wavelet transform in YCbCr color space, and it can be extracted blindly without access to the host image. However, fragile watermarking is based on an improved least significant bits' replacement approach in RGB components for image authentication. The authenticity and integrity of a suspicious image can be verified blindly without the host image and the original watermark. The combination of robust and fragile watermarking makes the proposed mechanism suitable for protecting valuable original images. The experimental results indicated that the proposed watermarking mechanism can withstand various processing attacks and accurately locate the tampered area of an image.

It is impractical to use traditional access control mechanisms to design a digital content access control mechanism for an organization since even a role-based access control mechanism only guarantees that it can be flexibly applied to the determined access policy for various roles in an organization. It cannot allow users to flexibly define various access rights for different digital contents for diverse applications. To make sure these requirements can be satisfied and also combine the hierarchy structure of organization to the access control and thus protect digital content from being illegally duplicated, printed, deleted, noted, modified and stored, in this paper, we apply a digital certificate to record each user's role(s) and the corresponding access rights inherited from the access policies defined by the administration department in the organization.

In this paper, we proposed a novel (2, 2) secret sharing scheme applied for grayscale images. This scheme can produce two noise-like shared images that help avoid a secret image being grabbed. The construction phase of shared image consists of producing two shared images of the secret image by a (7, 4) Hamming code operation. To prevent attackers from forging shared images, a logo is embedded into the shared images first by using Tianpsilas reversible data embedding scheme. Later, the embedded secret image is shuffled by Torus automorphism to enhance its security. Experimental results show that the noise-like shared images can be successfully generated by our proposed scheme.

Protecting data transmitted over the Internet has become a critical issue driven by the progress in data digitalization and communications networking over the past decade. The content being transmitted can be in the form of images, text and voice. To ensure that transmitted data are secure and cannot be tampered with or noticed by malicious attackers, several approaches have been proposed. Steganography is one general approach among them. The hiding capacity and image quality of stego-images are two major measures with which to evaluate an image hiding scheme. To enhance the hiding capacity of Fridrich et al.'s scheme, an improved image hiding scheme for grayscale images based on wet paper coding is proposed in this paper. The significant difference between Fridrich et al.'s scheme and ours is that we shuffle all the pixels in the host image by adopting toral automorphism, then segment all pixels before using our proposed wet pixel hiding strategies to hide the data. Experimental results show that our proposed scheme embeds a larger-sized secret image while maintaining acceptable image quality of the stego-image better than Fridrich et al.'s scheme does. Moreover, the computational cost of our proposed scheme is significantly less than that of Fridrich et al.'s scheme because inverse matrix and multiplication operations are not required. Therefore, our proposed scheme is suitable for real time applications.

In this paper, we propose a novel scheme called a self-verifying visual secret sharing scheme, which can be applied to both grayscale and color images. This scheme uses two halftone images. The first, considered to be the host image, is created by directly applying a halftoning technique to the original secret image. The other, regarded as the logo, is generated from the host image by exploiting the interpolation and error diffusion techniques. Because the set of shadows and the reconstructed secret image are generated by simple Boolean operations, no computational complexity and no pixel expansion occur in our scheme. Experimental results confirm that each shadow generated by our scheme is a noise-like image and eight times smaller than the secret image. Moreover, the peak signal-to-noise ratio value of the reconstructed secret image is larger than 33 dB. Based on the extracted halftone logo, the proposed scheme provides an effective solution for verifying the reliability of the set of collected shadows as well as the reconstructed secret image. Furthermore, the reconstructed secret image can be established completely if and only ifkout ofnvalid shadows have been collected. To achieve our objectives, four techniques were adopted: error diffusion, image clustering, interpolation, and inverse halftoning-based edge detection.

This paper presents a novel scheme to detect copied versions of digital images based on edge features of the images. The presented scheme is the first to explore the detection of “merged copies.” To successfully detect merged copies and shifted copies, a center detection mechanism is embedded in our scheme and two kinds of clustering approaches are adopted. Experimental results confirm that our scheme not only withstands most modifications of an original image but also offers good detection performance when dealing with various rotations, 32- or 64-pixels shifting, up to 66% cropping, or merged copies. Therefore, our presented scheme will be very helpful in detecting copies of digital images transmitted in an Internet environment.

Reversible data embedding is a very important issue, especially in dealing with sensitive images such as military data and medical data. Based on the edge-directed prediction scheme, the authors propose a reversible data-embedding scheme to embed secret information in original images. In the proposed scheme, an embedded pixel value is generalised according to a predetermined threshold and the difference between the predicted pixel value and its original pixel value. Experimental results show that the proposed scheme can provide great payload capacity while preserving the quality of the stego-image. The hiding capacity of the proposed scheme is about 1.7 times that of Tian's data-embedding scheme and twice that of Celik's.

Vector quantization (VQ) is a simple and widely used compression technology in many applications. For image compression, VQ provides both a fixed compression ratio and maintains acceptable distortion. However, the performance of VQ still can be improved in terms of the image quality of compressed images and codebook size used for encoding and decoding. In this paper, a new VQ-like image compression method is proposed to improve the performance of traditional VQ by using locally adaptive coding concept. The experimental results confirm that the image quality of the compressed image offered by the proposed method is higher than 30 dB on average, and the number of codewords used in our codebook is less than that required by traditional VQ.

Many researchers have studied reversible data hiding techniques in recent years and most have proposed reversible data hiding schemes that guarantee only that the original cover image can be reconstructed completely. Once the secret data are embedded in the compression domain and the receiver wants to store the cover image in a compression mode to save storage space, the receiver must extract the secret data, reconstruct the cover image, and compress the cover image again to generate compression codes. In this paper, we present a reversible data hiding scheme based on side match vector quantization (SMVQ) for digitally compressed images. With this scheme, the receiver only performs two steps to achieve the same goal: extract the secret data and reconstruct the original SMVQ compression codes. In terms of the size of the secret data, the visual quality, and the compression rate, experimental results show that the performance of our proposed scheme is better than those of other information hiding schemes for VQ-based and SMVQ-based compressed images. The experimental results further confirm the effectiveness and reversibility of the proposed scheme

Indices are modified so that the secret data can be hidden into the index-based cover image, and thereby the problem of the stego-image quality degradation occurs. If the stego-image quality degradation problem can be solved enabling the receiver to reconstruct the original indices after extracting the hidden secret data from the index-based stego-image, then the compressed cover image can be used repeatedly by different users. To achieve our goal, in this paper, a reversible data-hiding scheme based on a modified side match vector quantization (SMVQ) technique is proposed. Our experimental results confirm the effectiveness and the reversibility of the proposed scheme.

In this paper, a novel gray-level image-hiding scheme is proposed. The goal of this scheme is to hide multiple important gray-level images into another meaningful gray-level image. The secret images to be protected are first compressed using the vector quantization scheme. Then, the DES cryptosystem is conducted on the VQ indices and related parameters to generate the encrypted message. Finally, the encrypted message is embedded into the rightmost two bits of each pixel in the cover image. According to the experimental results, average image qualities of 44.320 dB and 30.885 dB are achieved for the embedded images and the retrieved secret images, respectively. In other words, multiple secret images can be effectively hidden into one host image of the same size. In addition, the proposed scheme strengthens the protection of the secret images by conducting the DES cryptosystem on the related parameters and the VQ indices of the compressed secret images. Therefore, the proposed scheme provides a secure approach to embed multiple important images into another meaningful image of the same size.

The improving technology and the ubiquity of the Internet have allowed more and more people to transmit data via the Internet. The contents of the transmission can be in the form of words, voices, images, or even computer animation. To protect the contents from interceptors' attention, the image hiding technology thus emerged. Some contents transmitted via the Internet can be confidential data such as highly valued product design blueprints or war plans, so it is important to pay more attention to the security of the transmitted data, or what we called secret image in this paper. The point of this paper is to enhance the security of the secret image without causing too much distortion to the host image and in the meantime to shorten the image hiding process time. For better protection, we adopted encryption process DES. In addition, we used greedy algorithm to shorten hiding process and to protect the host image from being severely distorted. To test our proposed method to see whether it indeed achieved its objective, we used two sets of images in our experiment. The results of the experiments showed, when k = 2, our PSNR is close to that of Wang et al.'s optimal LSB substitution, but is not significantly different from that of simple LSB substitution. However, our method took approximately only 1/7 of the time consumed by Wang et al. When k = 3, our PSNR is significantly higher than that of simple LSB substitution. The experimental results confirmed that our method could effectively protect host image quality and shorten the overall hiding time when it enhanced the security of the secret image.

In the past, most image hiding techniques have been applied only to gray scale images. Now, many valuable images are color images. Thus, it has become important to be able to apply image-hiding techniques to hide color images. In this paper, our proposed scheme can not only be applied to "a color host image hiding a color secret image", but also to "a color host image hiding a gray scale secret image". Our scheme utilizes the rightmost 3, 2 and 3 bits of the R, G, B channels of every pixel in the host image to hide related information from the secret image. Meanwhile, we utilize the leftmost 5, 6, 5 bits of the R, G, B channels of every pixel in the host image and set the remaining bits as zero to generate a palette. We then use the palette to conduct color quantization on the secret image to convert its 24-bit pixels into pixels with 8-bit palette index values. DES encryption is then conducted on the index values before the secret image is embedded into the rightmost 3, 2, 3 bits of the R, G, B channels of every pixel in the host image. The experimental results show that even under the worst case scenario our scheme guarantees an average host image PSNR value of 39.184 and an average PSNR value of 27.3415 for the retrieved secret image. In addition to the guarantee of the quality of host images and retrieved secret images, our scheme further strengthens the protection of the secret image by conducting color quantization and DES encryption on the secret image in advance. Therefore, our scheme not only expands the application area of image hiding, but is also practical and secure.