Clara Cruz-Ramos

Bio: Clara Cruz-Ramos is an academic researcher from Instituto Politécnico Nacional. The author has contributed to research in topics: Digital watermarking & Watermark. The author has an hindex of 8, co-authored 33 publications receiving 149 citations.

An effective fragile watermarking scheme for color image tampering detection and self-recovery

Abstract: In this paper, a fragile watermarking scheme for color-image authentication and self-recovery is proposed. Original image is divided into non-overlapping blocks, and for each i -th block, the watermarks used for recovery and authentication are generated, which are embedded into a different block according to an embedding sequence given by a permutation process. The designed scheme embeds the watermarks generated by each block within the 2-LSB, where a bit-adjustment phase is subsequently applied to increase the quality of the watermarked image. In order to increase the quality of the recovered image, we use in the post-processing stage the bilateral filter that efficiently suppresses noise preserving image edges. Additionally, in the tamper detection process high accuracy is achieved employing a hierarchical tamper detection algorithm. Finally, to solve tampering coincidence problem, three recovery watermarks are embedded in different positions to reconstruct a specific block, and a proposed inpainting algorithm is implemented to regenerate those regions affected by this problem. Simulation results demonstrate that the watermarked images appear to demonstrate higher quality, and the proposed novel scheme can reconstruct the alteration of extremely high rates (up to 80%), obtaining good quality for altered regions that are self-recovered with higher visual performance compared with a similar scheme from state of the-art methods.

Watermarking algorithm for authentication and self-recovery of tampered images using DWT

Abstract: Nowadays the use of digital images is a common practice worldwide, they are used for social, commercial or legal purposes among others; therefore it is important to detect malicious alterations in this type of content, to avoid possible social, legal or personal damages. Currently there are various proposed techniques to solve this problem. However, most of these proposals can only protect a region of interest within digital image, making feasible even with these methods, the alteration of certain regions that are not protected. Therefore, this paper proposes a digital image watermarking algorithm, which consists of two stages; the first one is to protect the digital image that is performed by Daubechies DWT, halftoning and QIM methods; the second one is used for authentication, detection and self-recovery of tampered regions, through IDWT, inverse halftoning and median filtering. Experimental results have demonstrated the effectiveness of the proposed algorithm, obtaining average PSNR values of 35 dB in the self-recovery image, even if the watermarked image was subjected to a JPEG compression using a quality factor QF=75.

Adaptive removable visible watermarking technique using dual watermarking for digital color images

Abstract: This paper proposes a removable visible watermarking system based on a dual watermark technique and blind removal. A visible watermark pattern is embedded in the cosine discrete transform (DCT) domain, taking into consideration the texture and luminance features of the watermark and host images to create a visible watermarked image. To prevent illegal visible watermark removal, the original watermark is embedded in an invisible manner in the visible watermarked image by employing the Quantization Index Modulation-Dither Modulation (QIM-DM) technique, thus ensuring that the original watermark cannot be obtained by malicious attacks. The visible watermark removal process is carried out using only the correct user’s keys, without the need for additional information, such as the original watermark or the original host image, which allows a high-quality image to be obtained; however, if the user’s keys used in the removal process are wrong, the visible watermarked image suffers higher distortion in its content, even in non-visible watermarked regions. The experimental results show that the proposed system outperforms previous related works in terms of blind removal, preservation of the quality of the unmarked recovered image, and higher visual degradation of the content in the recovered image if an illegal removal attempt is performed.

Watermarking Algorithm based on the DWT

Abstract: Watermarking is considered as a desirable alternative for copyright protection of digital materials such as images, video and audio. Two kinds of watermarking algorithms are usually used: the watermarking algorithms using pseudorandom patterns and those using visual recognizable patterns. The main advantage of watermarking algorithms embedding a visual recognizable pattern, which can be the owner or provider logotype, is that after the extraction process the pattern can be visually recognized and then identified. In general the visual recognizable patterns has a large impact and less ambiguity during the copyright claim process as compared with the random patterns, however the amount of information required by the visual recognizable pattern is much larger than the amount of information required by the pseudorandom one, and then to achieve imperceptibility and robustness of the watermark is more difficult. This paper proposes a discrete wavelet transform (DWT) based watermark embedding algorithm for visual recognizable pattern which uses the relation between the human visual system and the DWT for embedding the watermark is such way that it becomes imperceptible and robust. Evaluation results show the desirable features of proposed scheme.

Digital Video And Hdtv Algorithms And Interfaces

Abstract: digital video and hdtv algorithms and interfaces is available in our book collection an online access to it is set as public so you can get it instantly. Our book servers saves in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Merely said, the digital video and hdtv algorithms and interfaces is universally compatible with any devices to read.

An image fragile watermark scheme based on chaotic image pattern and pixel-pairs

Abstract: Fragile watermarking techniques for digital content have been studied in the past few years. Fragile watermarks are used to determine if a piece of watermarked digital content has been tampered, and distinguish tampered areas from non-tampered areas without referring to the original digital content. In this paper, a general framework for fragile watermark is proposed, and then a novel fragile watermarking scheme for image authentication is presented. The embedding process of fragile watermark starts from computing the difference image between the host image and its chaotic pattern. followed by mapping the difference image into a binary image. The binary image is then inserted into the least significant bit (LSB) bitplane of the host image. In addition, chaotic map is used to generate the chaotic pattern image, which can be used as secret key to improve the security of watermark algorithm. Due to employing permutation transform and chaotic image pattern, the corresponding position relation is broken between pixels in the watermarked image and the watermark. Simulation results and performance analysis show that the presented method is fast, secure and capable of detecting and localizing modification.

Efficient video watermarking based on singular value decomposition in the discrete wavelet transform domain

Abstract: This paper presents an efficient, robust, and imperceptible video watermarking technique based on singular value decomposition (SVD) performed in the Discrete Wavelet Transform (DWT) domain. In the proposed DWT-based SVD video watermarking method, the video frames are transformed with the DWT using two resolution levels. The high frequency band HH and the middle frequency bands LH and HL are SVD transformed and the watermark is hidden in them. The proposed DWT-based SVD video watermarking method is characterized by two improvements: (1) a cascade of two powerful mathematical transforms; the Discrete Wavelet Transform (DWT)-based SVD using additive method, and (2) an error correction code is applied and embeds the watermark with spatial and temporal redundancy. The aim of these improvements is to increase robustness against attacks based on video characteristics and the robustness against image processing attacks, realize high security level, protect the watermark against bit errors and obtain good perceptual quality. The proposed DWT-based SVD video watermarking method has been tested in the presence of video and image processing attacks and experimental results proved that the proposed DWT-based SVD video watermarking method survives attacks based on video characteristics and image processing techniques.

On discrete cosine transform

Abstract: The discrete cosine transform (DCT), introduced by Ahmed, Natarajan and Rao, has been used in many applications of digital signal processing, data compression and information hiding. There are four types of the discrete cosine transform. In simulating the discrete cosine transform, we propose a generalized discrete cosine transform with three parameters, and prove its orthogonality for some new cases. A new type of discrete cosine transform is proposed and its orthogonality is proved. Finally, we propose a generalized discrete W transform with three parameters, and prove its orthogonality for some new cases. Keywords: Discrete Fourier transform, discrete sine transform, discrete cosine transform, discrete W transform Nigerian Journal of Technological Research , vol7(1) 2012