Alavi Kunhu

A New Watermarking Algorithm for Color Satellite Images Using Color Logos and Hash Functions

This paper deals with a new robust and fragile watermarking algorithm which embeds 3bit index map of color logo watermark in the frequency domain and fragile information in the spatial domain of 24bit satellite color images. The color logo is used for copyright protection and the hash functions are used for checking the authenticity of the satellite image. The new algorithm caused minimal invisible distortion to the images demonstrated by high peak signal to noise ratio and similarity structure index measure values. The new watermarking technique has been successfully tested on a variety of satellite images. The robust watermarking scheme survived many attacks such as JPEG compression, resizing and rotation while the fragile watermark is very sensitive to the slightest modification to any RGB pixel, also it can accurately locate the tampered areas on the satellite color images.

A new multi watermarking algorithm for medical images using DWT and hash functions

In this paper, we propose a blind digital multi- watermarking algorithm for the copyright protection and authentication of medical images. When medical images are transmitted and stored in hospitals, strict security, confidentiality and integrity are required to protect from the illegal distortion and reproduction of the medical information. Medical image watermarking requires extreme care when embedding watermark information in the medical images because the additional information must not affect the image quality as this may cause the wrong diagnosis. The proposed algorithm contains one robust watermark for the ownership of the image and two fragile watermarks for checking the authenticity. The first two watermarks are embedded in the wavelet domain, while the third watermark is embedded in the spatial domain. In the proposed algorithm, the medical image is divided into two regions, called the Region of Interest and Region of Non Interest and all the three watermarks are embedded in the Region of Non-Interest. The new medical watermarking technique offers high peak signal to noise ratio and similarity structure index measure values. The technique was successfully tested on a variety of medical images and the experimental results show that the robust watermark survived many intentional and non intentional attacks, while the fragile watermark is sensitive to any slight tampering on the medical images.

Hybrid DWT-DCT-Hash function based digital image watermarking for copyright protection and content authentication of DubaiSat-2 images

This paper presents a new technique for copyright protection and content authentication of satellite images. The novelty in the presented approach consists in designing a hybrid Discrete Wavelet Transform (DWT), Discrete Cosine Transform (DCT) and hash function based digital image watermarking. In this study, two watermarks are embedded in the cover image called robust copyright watermark and fragile authentication watermark. The robust watermark is embedded in hybrid frequency and wavelet domain by applying DWT and DCT respectively. Such two steps embedding allows the proposed approach to provide better imperceptibility in harmony with the human visual system and offers higher robustness against signal processing attacks. Subsequently, the fragile watermark is embedded in a spatial domain using the hash function approach. The proposed hybrid watermarking technique has been tested on DubaiSat-2 images with 1 meter resolution. The experimental results show that the proposed method is robust against JPEG compression, rotation and resizing attacks. In addition, the multi-watermarked image has a good transparency and the fragile watermark is sensitive to any tampering.

A new multi watermarking algorithm based on DWT and hash functions for color satellite images

This paper deals with a blind multi watermarking algorithm which embeds robust ownership watermark and fragile authentication information into satellite images to protect the copyright ownership and integrity of the images. The robust watermark is embedded first in the discrete wavelet transform (DWT) and the second hash authentication code is embedded in the spatial domain. The new technique offers high peak signal to noise ratio (PSNR) and similarity structure index measure (SSIM) values. The technique was successfully tested on a variety of satellite images. The fragile watermark is sensitive to any slight tampering and can locate the area of the editing. The robust watermark survived many intentional and non intentional attacks.

Multi-watermarking scheme for copyright protection and content authentication of DubaiSat-1 satellite imagery

A non-secure transmission channel is considered as a major challenge in remote sensing. The commercial value of satellite imagery and the sensitive information it contains led engineers to look for different means to secure the ownership of satellite imagery and preventing the illegal use of these resources. Therefore, a blind multi-watermarking scheme for copyright protection and image authentication is proposed. The multi-watermarking scheme is based on designing two back-to-back encoders. The first encoder embeds a robust ownership watermark in a frequency domain of satellite imagery using Discrete Cosine Transform (DCT) approach. Whereas, the second encoder embeds a fragile authentication information into a spatial domain of a watermarked image using Message Digest Encryption Key algorithm. This study was conducted on DubaiSat-1 satellite imagery owned by Emirates Institution for Advanced Science and Technology (EIAST). The simulation results demonstrate that the proposed scheme is robust against many intentional and unintentional attacks. Moreover, it shows a very high ability for tamper detection.

A new watermarking algorithm for scanned grey PDF files using DWT and hash function

This paper deals with the development and assessment of a watermarking technique which is suitable for scanned PDF documents. The watermark will serve two purposes. The first one is to protect the copyright ownership. This watermark is a logo which can be extracted even if the document has gone through slight image manipulations. The second one is to authenticate the document. A slight editing in the document will change the second watermark and indicate forgery. The algorithm was tested successfully on a variety of scanned documents and the performances of the algorithm were assessed.

Discrete cosine transform and hash functions toward implementing a (robust-fragile) watermarking scheme

This paper proposes a blind multi-watermarking scheme based on designing two back-to-back encoders. The first encoder is implemented to embed a robust watermark into remote sensing imagery by applying a Discrete Cosine Transform (DCT) approach. Such watermark is used in many applications to protect the copyright of the image. However, the second encoder embeds a fragile watermark using ‘SHA-1’ hash function. The purpose behind embedding a fragile watermark is to prove the authenticity of the image (i.e. tamper-proof). Thus, the proposed technique was developed as a result of new challenges with piracy of remote sensing imagery ownership. This led researchers to look for different means to secure the ownership of satellite imagery and prevent the illegal use of these resources. Therefore, Emirates Institution for Advanced Science and Technology (EIAST) proposed utilizing existing data security concept by embedding a digital signature, “watermark”, into DubaiSat-1 satellite imagery. In this study, DubaiSat-1 images with 2.5 meter resolution are used as a cover and a colored EIAST logo is used as a watermark. In order to evaluate the robustness of the proposed technique, a couple of attacks are applied such as JPEG compression, rotation and synchronization attacks. Furthermore, tampering attacks are applied to prove image authenticity.

Index mapping based hybrid DWT-DCT watermarking technique for copyright protection of videos files

In this paper, we propose a new blind colour video watermarking technique for the copyright protection of multimedia colour videos using index mapping concept. The novelty in the presented approach consists in designing a hybrid Discrete Wavelet Transform (DWT) and Discrete Cosine Transform (DCT) based digital video watermarking of colour watermark logo using index mapping technique. The distortion caused by watermarking is assessed by using peak signal to noise ratio (PSNR) and similarity structure index measure (SSIM) and robustness against different types of attacks have been assessed using StirMark. The proposed video watermarking algorithm provides better imperceptibility in harmony with the human visual system and offers higher robustness against signal processing attacks.

A new hybrid watermarking algorithm for MRI medical images using DWT and hash functions

This paper deals with a blind hybrid digital watermarking algorithm for the copyright protection and authentication of magnetic resonance tomography images. Medical image watermarking requires extreme care when embedding watermark information in the medical images, to protect the image quality from being violated and to avoid the wrong diagnosis that might occur. The proposed algorithm contains robust watermark for the ownership protection and fragile watermarks for checking the authenticity. In the proposed algorithm, the medical image is divided into two regions, called the Region of Interest and Region of Non-Interest using histogram technique and the watermarks are embedded in both wavelet domain and spatial domain in the Region of Non-Interest Area. The proposed hybrid watermarking technique was successfully tested on a variety of MRI medical images and offerd high peak signal to noise ratio and similarity structure index measure values.This paper deals with a blind hybrid digital watermarking algorithm for the copyright protection and authentication of magnetic resonance tomography images. Medical image watermarking requires extreme care when embedding watermark information in the medical images, to protect the image quality from being violated and to avoid the wrong diagnosis that might occur. The proposed algorithm contains robust watermark for the ownership protection and fragile watermarks for checking the authenticity. In the proposed algorithm, the medical image is divided into two regions, called the Region of Interest and Region of Non-Interest using histogram technique and the watermarks are embedded in both wavelet domain and spatial domain in the Region of Non-Interest Area. The proposed hybrid watermarking technique was successfully tested on a variety of MRI medical images and offerd high peak signal to noise ratio and similarity structure index measure values.

Design and implementation of highly efficient digital watermarking prototype for securing copyright and authentication of satellite imagery

Satellite imagery is considered as a powerful tool to map and monitor natural and man-made resources changes globally. Moreover, it greatly contributes to boost scientific researches, supports decision making process regarding important issues and has a tremendous potential to improve economic outcomes. However, the dramatic growth in the field of communication and the internet allows satellite imagery to be easily distributed, tampered and duplicated by unauthorized users. As a result, the protection of its intellectual property has become of a great demand. To overcome this issue, the concept of “watermarking” has been introduced as a potential solution for copyright protection and ownership authentication of satellite images. The principle of watermarking here is based on embedding a pattern of invisible identification information (for instance logo) into a satellite image so that it can be detected or extracted later to identify the copyright owner. Unlike other sorts of data, satellite images are complex in nature and contain very sensitive information which can be easily degraded by inserting additional information. This means that applying watermarking technique to satellite images would affect negatively on its quality, which totally interferes with the main purpose of building high resolution satellites. Thus, a proper technique should be developed to overcome this problem. Recently, digital watermarking has been a hot research topic in academia and industry, where a wide number of schemes have been proposed and evaluated. This paper deals with the design, implementation and evaluation of a novel watermarking model for preserving the copyright and authentication of DubaiSat-2 images. The proposed algorithm must be robust against intentional and non-intentional attacks such as compression, scaling, rotation, filtering, cropping, contrast enhancement etc. In addition, the algorithm should be fragile in such a way that it should be very sensitive to any minor tampering/modification and it should precisely detect tampered area on the satellite image. Moreover, the watermark should be imperceptible to the human eye. Five quality indices are used to assess the performance of the proposed prototype, which consist of the peak signal to noise ratio (PSNR), wavelet domain signal to noise ratio (WSNR), structure similarity index measurement (SSIM), normalized correlation (NC) and mean square error (MSE).