Showing 3 results for Watermarking
S. Mohammadi, S. Talebi, A. Hakimi,
Volume 8, Issue 2 (6-2012)
Abstract
In this paper we introduce two innovative image and video watermarking
algorithms. The paper’s main emphasis is on the use of chaotic maps to boost the
algorithms’ security and resistance against attacks. By encrypting the watermark
information in a one dimensional chaotic map, we make the extraction of watermark for
potential attackers very hard. In another approach, we select embedding positions by a two
dimensional chaotic map which enables us to satisfactorily distribute watermark
information throughout the host signal. This prevents concentration of watermark data in a
corner of the host signal which effectively saves it from being a target for attacks that
include cropping of the signal. The simulation results demonstrate that the proposed
schemes are quite resistant to many kinds of attacks which commonly threaten
watermarking algorithms.
R. Samadi, S. A. Seyedin,
Volume 10, Issue 2 (6-2014)
Abstract
Unintentional attacks on watermarking schemes lead to degrade the watermarking channel, while intentional attacks try to access the watermarking channel. Therefore, watermarking schemes should be robust and secure against unintentional and intentional attacks respectively. Usual security attack on watermarking schemes is the Known Message Attack (KMA). Most popular watermarking scheme with structured codebook is the Scalar Costa Scheme (SCS). The main goal of this paper is to increase security and robustness of SCS in the KMA scenario. To do this, SCS model is extended to more general case. In this case, the usual assumption of an infinite Document to Watermark Ratio (DWR) is not applied. Moreover watermark is assumed to be an arbitrary function of the quantization noise without transgressing orthogonality as in the Costa’s construction. Also, this case is restricted to the structured codebooks. The fundamental trade-off is proved between security and robustness of Generalized SCS (GSCS) in the KMA scenario. Based on this trade-off and practical security attack on SCS, a new extension of SCS is proposed which is called Surjective-SCS (SSCS). In the absence of robustness attack, the SSCS has more security than SCS in the same DWR. However, the SSCS achieves more security and robustness than SCS only in low Watermark to Noise Ratio (WNR) regime or low rate communications.
A. Amiri, S. Mirzakuchaki,
Volume 16, Issue 3 (9-2020)
Abstract
Watermarking has increased dramatically in recent years in the Internet and digital media. Watermarking is one of the powerful tools to protect copyright. Local image features have been widely used in watermarking techniques based on feature points. In various papers, the invariance feature has been used to obtain the robustness against attacks. The purpose of this research was based on local feature-based stability as the second-generation of watermarking due to invariance feature to achieve robustness against attacks. In the proposed algorithm, initially, the points were identified by the proposed function in the extraction and Harris and Surf algorithms. Then, an optimal selection process, formulated in the form of a Knapsack problem. That the Knapsack problem algorithm selects non-overlapping areas as they are more robust to embed watermark bits. The results are compared with each of the mentioned feature extraction algorithms and finally, we use the OPAP algorithm to increase the amount of PSNR. The evaluation of the results is based on most of the StirMark criterion.
