Nazir A. Loan

Robust and blind watermarking technique in DCT domain using inter-block coefficient differencing

In this paper, a robust blind watermarking technique, based on block-based DCT coefficient modification is proposed. The difference between two DCT coefficients of the adjacent blocks at the same position is calculated. Depending upon the watermark bit to be embedded; this difference is brought in a particular predefined range which is achieved by modifying one of the two DCT coefficients. The amount of modification to a DCT coefficient of a block depends upon the scaling variable, DC coefficient and median of certain zig-zag ordered AC coefficients of that block. The robustness of the proposed scheme has been examined for various singular and hybrid attacks. Comparison results reveal that the proposed technique has a higher degree of robustness against various singular and hybrid attacks. Further a watermark of good quality is extracted even after various simultaneous attacks on the system.

Information hiding in medical images: a robust medical image watermarking system for E-healthcare

Electronic transmission of the medical images is one of the primary requirements in a typical Electronic-Healthcare (E-Healthcare) system. However this transmission could be liable to hackers who may modify the whole medical image or only a part of it during transit. To guarantee the integrity of a medical image, digital watermarking is being used. This paper presents two different watermarking algorithms for medical images in transform domain. In first technique, a digital watermark and Electronic Patients Record (EPR) have been embedded in both regions; Region of Interest (ROI) and Region of Non-Interest (RONI). In second technique, Region of Interest (ROI) is kept untouched for tele-diagnosis purpose and Region of Non-Interest (RONI) is used to hide the digital watermark and EPR. In either algorithm 8 × 8 block based Discrete Cosine Transform (DCT) has been used. In each 8 × 8 block two DCT coefficients are selected and their magnitudes are compared for embedding the watermark/EPR. The selected coefficients are modified by using a threshold for embedding bit a ‘0’ or bit ‘1’ of the watermark/EPR. The proposed techniques have been found robust not only to singular attacks but also to hybrid attacks. Comparison results viz-a - viz payload and robustness show that the proposed techniques perform better than some existing state of art techniques. As such the proposed algorithms could be useful for e-healthcare systems.

Information hiding in edges: A high capacity information hiding technique using hybrid edge detection

The multimedia security is becoming more and more important as the data being exchanged on the Internet is increasing exponentially. Though cryptography is one of the methods which is used to secure the data during transit, but the camouflaged appearance of the scrambled data alerts the adversary about some critical information being shared. In such a scenario, steganography has been used as an alternate solution to secure the secret information. In this paper a color image steganographic algorithm based on hybrid edge detection is proposed. The color image is partitioned into constituent Red (R), Green (G) and Blue (B) planes. Hybrid edge detection is used for finding the edge and non-edge pixels of Green and Blue planes of cover image. The Green and Blue planes are used for hiding the data while Red plane holds the pixel status (whether edge or non-edge) of these planes. The RC4 encryption algorithm is used to encrypt secret message before embedding it in the cover image to enhance security of the secret data. A fragile watermark/logo (whose size is less than 1% of total secret data) has been embedded, besides secret data in the cover image, to facilitate content authentication and early tamper detection. At the receiver, firstly logo is extracted. If it is same as one embedded at transmitter, indicating that secret data has not been altered during transit, secret data is extracted. Otherwise (if extracted logo is not same as used at input) the receiver does not waste critical time to extract compromised data but sends an automatic retransmission request. Experimental investigations reveal that the proposed scheme is capable of providing high quality of stego-images for a fairly high pay load. A comparison of the proposed technique with some state of art schemes substantiates the above arguments.

A high capacity data hiding scheme based on edge detection and even-odd plane separation

In this paper a high capacity data hiding technique based on hybrid edge detection and even-odd pixel separation is proposed. The even-odd sub planes of Red, Green and Blue of the cover image are extracted then Blue and Green channel sub planes are utilized for hiding the secret data while Red channel sub planes are used to hold the status (edge or non-edge) of the pixels of Green and Blue channel sub planes. The experimentation has been carried out for different capacities of data bits and the results are compared with a state of art data hiding technique which reveals that the proposed technique has high capacity. Further good quality stego-images are obtained.

A New Reversible and high capacity data hiding technique for E-healthcare applications

A high capacity and reversible data hiding technique capable of tamper detection and localisation of medical images has been proposed in this paper. Image interpolation has been used to scale up the original image to obtain the cover image. The cover image is divided into n×n non-overlapping blocks. In every block pixels are classified into two types: Seed pixels and non-seed pixels. The Electronic Patient Record (EPR) is embedded only in non-seed pixels while as no embedding is carried out in seed pixels to facilitate reversibility. A fragile watermark coupled with Block Checksum has been embedded in addition to EPR for detecting any tamper to the patient data during its transit from transmitter to receiver. Embedding has been carried out using Intermediate Significant Bit Substitution (ISBS) to prevent the scheme from LSB removal/replacement attack. The scheme has been evaluated for perceptual imperceptibility and content authentication by subjecting it to various image processing and geometric attacks. Experimental results reveal that the proposed system is capable of providing high quality watermarked images for fairly high payload while maintaining reversibility. Further it has been observed that the proposed technique is able to detect tamper for all the image processing and geometric attacks carried out on it. A comparison of the observed results with that of some state-of-art schemes show that our scheme performs better and as such is an ideal candidate for content authentication of EPR in a typical e-healthcare system.

A Robust and Computationally Efficient Digital Watermarking Technique Using Inter Block Pixel Differencing

The growth of internet coupled with the rise in networked infrastructure has resulted in exponential increase in the multimedia content being shared over the communication networks. The advancement in technology has resulted in increase in multimedia piracy. This is due to the fact that it is very easy to copy, duplicate and distributes multimedia content using current day technology. In such a scenario Digital Rights Management is one of the prominent issues to be dealt with and tremendous work is going on in this direction round the globe. Digital watermarking and fingerprinting have emerged as fundamental technologies to cater to DRM issues. These technologies have been found to be of prominent use in content authentication, copy protection, copyright control, broadcast monitoring and forensic applications. Various requirements of a digital watermarking system include Imperceptibility, Robustness, Security, Payload and Computational complexity. The main requirement of real time DRM systems is lesser computational complexity and high robustness. This chapter proposes and analyses a robust and computational efficient Image watermarking technique in spatial domain based on Inter Block Pixel Difference (IBPD). The cover image is divided into 8 × 8 non overlapping blocks and difference between intensities of two pixels of adjacent blocks at predefined positions is calculated. Depending upon the watermark bit to be embedded; both the pixels are modified to bring the difference in a predefined zone. The experimental results reveal that the proposed scheme is capable of providing high quality watermarked images in addition to being robust to various singular and hybrid image processing and geometrical attacks like Salt and Pepper noise, Gaussian noise, Sharpening, Compression, Rotation and Cropping etc. Further the implementation of the scheme in pixel domain reduces the computational complexity drastically and makes the proposed scheme an ideal candidate for real time applications.

Pixel Repetition Technique: A High Capacity and Reversible Data Hiding Method for E-Healthcare Applications

Electronic healthcare is changing the world worldwide scenario of the conventional healthcare. Transmission of medical images in e-healthcare system is of greater importance, because of the valuable information carried out by them for the purpose of tele-diagnosis and tele-medicine. For successful tele-diagnosis, it is imperative that the medical images should not be tampered with during transit. In this chapter, a high capacity and reversible data hiding system utilizing Pixel Repetition Technique (PRT) has been proposed. The usage of PRT for preprocessing reduces the computational complexity drastically. The proposed system is capable of any sort of tamper detection. This has been achieved by embedding a fragile watermark (computed from checksum of the cover medium blocks) in addition to electronic patient record (EPR). Block-wise division of cover image and intermediate significant bit (ISB) substitution have been used for data embedding. A detailed experimentation carried out shows that besides supporting high payload and reversibility our technique is capable of detecting any tamper caused due to signal processing and geometric attacks. Further, less computational complexity makes the proposed scheme an ideal candidate for real-time electronic healthcare applications.

Utilizing neighborhood coefficient correlation: a new image watermarking technique robust to singular and hybrid attacks

A new blind digital image watermarking algorithm with watermark embedded in discrete cosine transform (DCT) coefficients is presented in this paper. The proposed scheme exploits correlation between DCT coefficients in neighborhood blocks for embedding. The watermark is embedded by modifying two DCT coefficients, one pertaining to a block in which watermark bit (0 or 1) is to be embedded and the other corresponding to the selected neighborhood block. Both the selected coefficients are modified by a modification factor so that the difference between the pair of coefficients is brought to a predefined zone. This difference between two DCT coefficients is used to extract watermark. The proposed technique has been tested for different attacks like JPEG compression, rotation, cropping, filtering, gaussian noise, salt and pepper noise, histogram equalization etc. It has been observed that the scheme is highly robust not only for the above mentioned attacks used singularly, but also for different possible combinations of simultaneous attacks. A comparison of the proposed technique with some state of art existing algorithms reveals that our scheme provides better results in terms of quality of watermarked images, payload and robustness.

Hiding Electronic Patient Record (EPR) in medical images

A high capacity and semi-reversible data hiding scheme based on Pixel Repetition Method (PRM) and hybrid edge detection for scalable medical images has been proposed in this paper. PRM has been used to scale up the small sized image (seed image) and hybrid edge detection ensures that no important edge information is missed. The scaled up version of seed image has been divided into 2×2 non overlapping blocks. In each block there is one seed pixel whose status decides the number of bits to be embedded in the remaining three pixels of that block. The Electronic Patient Record (EPR)/data have been embedded by using Least Significant and Intermediate Significant Bit Substitution (ISBS). The RC4 encryption has been used to add an additional security layer for embedded EPR/data. The proposed scheme has been tested for various medical and general images and compared with some state of art techniques in the field. The experimental results reveal that the proposed scheme besides being semi-reversible and computationally efficient is capable of handling high payload and as such can be used effectively for electronic healthcare applications.

A reversible and secure patient information hiding system for IoT driven e-health

Abstract Internet of things (IoT) coupled with mobile cloud computing has made a paradigm shift in the service sector. IoT-assisted mobile cloud based e-healthcare services are making giant strides and are likely to change the conventional ways of healthcare service delivery. Though numerous approaches for preventing unauthorized access to information exchanged between a mobile phone and cloud platform do exist, but there is no security mechanism to prevent unauthorized access by the cloud administrators. With an aim to ensure security of client data such as Electronic Patient Records (EPR), we propose a novel high-capacity and reversible data hiding approach for securely embedding EPR within the medical images using Optimal Pixel Repetition (OPR). OPR converts every pixel of the input image to a 2 × 2 block to facilitate reversibility by ensuring all the pixels in a 2 × 2 block to have different values. Since a 2 × 2 block is comprised of 4-pixel elements, which could be arranged in sixteen possible ways; we generate a lookup table corresponding to sixteen possible positions of pixels. EPR hiding in each block is achieved by permuting the pixels of a block according to the four-bit word of secret data, resulting in a histogram invariant stego image. The histogram invariance improves the robustness of the proposed scheme to statistical attacks. A stego image is said to hide embedded data securely, when it provides better imperceptivity for an appreciably high payload. Thus, while using information embedding approach for securing client data on a mobile-cloud platform, high imperceptivity is a desirable feature. Experimental results show that average PSNR obtained is 42 dB for payload 1.25 bpp by our scheme, showing its effectiveness for preventing unauthorized access to client’s sensitive data.