Bee Ee Khoo

Authentication and Data Hiding Using a Hybrid ROI-Based Watermarking Scheme for DICOM Images

Authenticating medical images using watermarking techniques has become a very popular area of research, and some works in this area have been reported worldwide recently. Besides authentication, many data-hiding techniques have been proposed to conceal patient’s data into medical images aiming to reduce the cost needed to store data and the time needed to transmit data when required. In this paper, we present a new hybrid watermarking scheme for DICOM images. In our scheme, two well-known techniques are combined to gain the advantages of both and fulfill the requirements of authentication and data hiding. The scheme divides the images into two parts, the region of interest (ROI) and the region of non-interest (RONI). Patient’s data are embedded into ROI using a reversible technique based on difference expansion, while tamper detection and recovery data are embedded into RONI using a robust technique based on discrete wavelet transform. The experimental results show the ability of hiding patient’s data with a very good visual quality, while ROI, the most important area for diagnosis, is retrieved exactly at the receiver side. The scheme also shows some robustness against certain levels of salt and pepper and cropping noise.

A new robust and secure digital image watermarking scheme based on the integer wavelet transform and singular value decomposition

Abstract In this paper, a new robust and secure digital image watermarking scheme that can be used for copyright protection is proposed. The scheme uses the integer wavelet transform (IWT) and singular value decomposition (SVD). The grey image watermark pixels values are embedded directly into the singular values of the 1-level IWT decomposed sub-bands. Experimental results demonstrate the effectiveness of the proposed scheme in terms of robustness, imperceptibility and capacity due to the IWT and SVD properties. A challenge due to the false positive problem which may be faced by most of SVD-based watermarking schemes has been solved in this work by adopting a digital signature into the watermarked image. The proposed digital signature mechanism is applied to generate and embed a digital signature after embedding the watermarks; the ownership is then authenticated before extracting watermarks. Thus, the proposed scheme achieved the security issue where the false positive problem is solved, in addition to that, the scheme is considered as a blind scheme. A computer simulation is used to verify the feasibility of the proposed scheme and its robustness against various types of attacks and to compare it with some previous schemes. Furthermore, the statistical Wilcoxon signed rank test is employed to certify the effectiveness of the proposed scheme.

Passive detection of copy-move forgery in digital images: state-of-the-art.

Currently, digital images and videos have high importance because they have become the main carriers of information. However, the relative ease of tampering with images and videos makes their authenticity untrustful. Digital image forensics addresses the problem of the authentication of images or their origins. One main branch of image forensics is passive image forgery detection. Images could be forged using different techniques, and the most common forgery is the copy-move, in which a region of an image is duplicated and placed elsewhere in the same image. Active techniques, such as watermarking, have been proposed to solve the image authenticity problem, but those techniques have limitations because they require human intervention or specially equipped cameras. To overcome these limitations, several passive authentication methods have been proposed. In contrast to active methods, passive methods do not require any previous information about the image, and they take advantage of specific detectable changes that forgeries can bring into the image. In this paper, we describe the current state-of-the-art of passive copy-move forgery detection methods. The key current issues in developing a robust copy-move forgery detector are then identified, and the trends of tackling those issues are addressed.

High capacity data hiding schemes for medical images based on difference expansion

Since the difference expansion (DE) technique was proposed, many researchers tried to, improve its performance in terms of hiding capacity and visual quality. In this paper, a new scheme, based on DE is proposed in order to increase the hiding capacity for medical images. One of the characteristics of medical images, among the other types of images, is the large smooth regions. Taking advantage of this characteristic, our scheme divides the image into two regions; smooth region and non-smooth region. For the smooth region, a high embedding capacity scheme is applied, while the original DE method is applied to the non-smooth region. Sixteen DICOM images of different modalities were used for testing the proposed schemes. The results showed that the proposed scheme has higher hiding capacity compared to the original schemes.

Block-based discrete wavelet transform-singular value decomposition image watermarking scheme using human visual system characteristics

Digital watermarking has been suggested as a way to achieve digital protection. The aim of digital watermarking is to insert the secret data into the image without significantly affecting the visual quality. This study presents a robust block-based image watermarking scheme based on the singular value decomposition (SVD) and human visual system in the discrete wavelet transform (DWT) domain. The proposed method is considered to be a block-based scheme that utilises the entropy and edge entropy as HVS characteristics for the selection of significant blocks to embed the watermark, which is a binary watermark logo. The blocks of the lowest entropy values and edge entropy values are selected as the best regions to insert the watermark. After the first level of DWT decomposition, the SVD is performed on the low-low sub-band to modify several elements in its U matrix according to predefined conditions. The experimental results of the proposed scheme showed high imperceptibility and high robustness against all image processing attacks and several geometrical attacks using examples of standard and real images. Furthermore, the proposed scheme outperformed several previous schemes in terms of imperceptibility and robustness. The security issue is improved by encrypting a portion of the important information using Advanced Standard Encryption a key size of 192-bits (AES-192).

Two-dimensional difference expansion (2D-DE) scheme with a characteristics-based threshold

Fragile watermarking is commonly used for content authentication and tamper detection in digital multimedia. For some critical applications, such as medical systems, the fragile watermarking system should be based on a reversible data hiding scheme. The Difference Expansion (DE) technique is a popular reversible data hiding method. In this paper, we adopt a two-dimensional difference expansion technique (2D-DE) to increase the hiding capacity. The proposed scheme is a fragile block-based scheme where the image is divided into blocks of 4x4 pixels, and these expandable blocks are embedded with 16 bits of payload. In addition to increasing the achieved capacity, we study the effect of selecting the blocks to be embedded according to characteristics such as standard deviation, smoothness, and uniformity. These characteristics can be used as selection criteria to enhance the visual quality. The experimental results demonstrate a very high embedding capacity equals to approximately 1 bit per pixel (bpp). Moreover, a threshold based on the standard deviation can be used to control the hiding capacity and predict the reduction in hiding capacity that will enhance the visual quality.

ROI-based tamper detection and recovery for medical images using reversible watermarking technique

Digital image watermarking is proposed to overcome the problems of security, capacity and cost in health care management systems. Medical images, unlike most of images, require extreme care when embedding additional data within them because the additional information must not affect the image quality and readability. In order to overcome any misdiagnose caused by embedding data into medical images, lossless data hiding techniques have been developed. This paper presents a lossless watermarking technique for Ultrasound (US) images. The proposed technique adopts a high-capacity reversible data hiding scheme based on difference expansion (DE). It can be used to hide patients data hiding and protecting the region of interest (ROI) with tamper detection and recovery capability. The experimental results show that the original image can be exactly extracted from the watermarked one in case of no tampering. In case of tampered ROI, tampered area can be localized and recovered losslessly.

Robust reversible watermarking scheme using Slantlet transform matrix

A new robust reversible image watermarking method based on Slantlet transform (SLT) is proposed.The host image is divided into non-overlapping blocks before applying SLT and the histogram modification process is applied to prevent the overflow underflow of the pixel values in each block.The watermark embedding process depends on modifying the mean values of the SLT coefficients for one subband in each block.Experimental tests based on 100 general images and 100 medical images demonstrate the efficiency of the proposed scheme.The results prove that the proposed method is completely reversible with improved capacity, robustness and invisibility. The need for a robust reversible watermarking method has recently attracted more attention. This paper presents a novel robust reversible watermarking scheme based on using the Slantlet transform matrix to transform small blocks of the original image and hiding the watermark bits by modifying the mean values of the carrier subbands. The problem of overflow/underflow has been avoided by using histogram modification process. Extensive experimental tests based on 100 general images and 100 medical images demonstrate the efficiency of the proposed scheme. The proposed scheme has robustness against different kinds of attacks and the results prove that it is completely reversible with improved capacity, robustness, and invisibility in comparison with the previous methods.

A new robust lossless data hiding scheme and its application to color medical images

The last few years witnessed an increased interest in the robust lossless data hiding schemes because they can verify the main requirements of the lossless data hiding (i.e., reversibility, capacity, and invisibility) and at the same time provide robustness against attacks. The reversibility is one of the important requirements of those methods. Another important requirement is the improvement of the robustness against attacks. The methods that improve the robustness are at the cost of reducing capacity and invisibility. Taking into consideration the need for improving the four requirements that have been mentioned above, this paper presents a novel robust lossless data hiding method in the transform domain. The proposed algorithm depends on transforming non-overlapping blocks of the host image using Slantlet transform (SLT) matrix and embedding data bits by modifying the difference between the mean values of the SLT coefficients in the high frequency subbands. As a practical application, the proposed algorithm has been adjusted in order to be applied to the color medical images. The data bits can be embedded not only in a single channel but also in the three channels of the RGB color image and thus further improving the embedding capacity. The results of the experiments that were conducted and the comparisons with the previous robust lossless data hiding (i.e., robust reversible watermarking) methods prove the effectiveness of the proposed algorithm. A new robust lossless data hiding scheme in the transform domain is proposed.The Slantlet transform (SLT) has been calculated using matrix multiplication.The method provides complete reversibility after watermark extraction.Robustness against different attacks has been obtained.The proposed scheme has been successfully applied to color medical images.

Completed Local Ternary Pattern for Rotation Invariant Texture Classification

Despite the fact that the two texture descriptors, the completed modeling of Local Binary Pattern (CLBP) and the Completed Local Binary Count (CLBC), have achieved a remarkable accuracy for invariant rotation texture classification, they inherit some Local Binary Pattern (LBP) drawbacks. The LBP is sensitive to noise, and different patterns of LBP may be classified into the same class that reduces its discriminating property. Although, the Local Ternary Pattern (LTP) is proposed to be more robust to noise than LBP, however, the latters weakness may appear with the LTP as well as with LBP. In this paper, a novel completed modeling of the Local Ternary Pattern (LTP) operator is proposed to overcome both LBP drawbacks, and an associated completed Local Ternary Pattern (CLTP) scheme is developed for rotation invariant texture classification. The experimental results using four different texture databases show that the proposed CLTP achieved an impressive classification accuracy as compared to the CLBP and CLBC descriptors.