Wyniki wyszukiwania - BazTech

1

Hybrid Watermarking Algorithm using Finite Radon and Fractional Fourier Transform

Sharmaa J. B., Sharmaa K. K., Purohit S. D., Atangana A.

Fundamenta Informaticae

|

2017

|

Vol. 151, nr 1/4

523--543

EN

Watermarking is proposed as solution to authentication, copyright protection and security requirements of multimedia objects (speech, image and video). In this paper a watermarking scheme based on finite radon transform (FRAT), fractional Fourier Transform (FRFT) and singular value decomposition is proposed. In the proposed scheme, image to be watermarked is first transformed by finite radon transform, the radon transformed image is further transformed by FRFT, and singular values of FRFT transformed image are modified to embed the watermark. Inverse transformation is applied to obtain watermarked image. Simulations are performed under various test conditions with different FRFT transform angles for improved robustness and visual transparence of watermarked image. Results of the proposed scheme are better in comparison to the existing schemes for most of the attacks. Proposed scheme provide additional degree of freedom in security, robustness, payload capacity and visual transparence. Proposed scheme can also be used to communicate or store the watermarked image as erasure code, to reduce communication errors over a network, due to the use of FRAT.

2

A Robust Digital Watermarking Based on Local Complex Angular Radial Transform

Niu P.-P., Wang X.-Y., Yang H.-Y., Wang P., Wang A.-L.

Fundamenta Informaticae

|

2014

|

Vol. 135, nr 3

243--268

EN

Geometric distortions that cause displacement between embedding and detection are usually difficult for watermark to survive. It is a challenging work to design a robust image watermarking scheme against geometric distortions, especially for local geometric distortions. Based on probability density and complex angular radial transform theory, a new image watermarking algorithm robust to geometric distortions is proposed in this paper. We firstly extract the steady image feature points by using new image feature point detector, which is based on the probability density. Then we build the affine invariant local feature regions based on probability density auto-correlation matrix. And finally, we present a new image watermarking algorithm robust to geometric distortions, in which the digital watermark is embedded into the local complex angular radial transform (CART) coefficients. Experiments results show that the proposed image watermarking is not only invisible and robust against common image processing operations, but also robust against the geometric distortions.

3

Efficient image watermarking in the transform domain with the discrete trigonometric transforms

Korohoda P., Dąbrowski A.

Elektronika : konstrukcje, technologie, zastosowania

|

2009

|

Vol. 50, nr 3

39-42

EN

In this paper a possibility of the use of the whole set of 16 discrete trigonometric transforms (DTTs) is presented for efficient image watermarking in the transform domain. The proposed technique is based on transformation of the whole image with the watermark defined in a part of the transform domain. Advantageous properties of this approach are shown for all DTTs. Two attacking techniques, namely: Gaussian filtering and JPEG coding have been selected to verify the efficiency of all DTTs applied in the considered task. Additional discussion of a case of two different DTTs the first one used for watermark generation and the second for the reconstruction, has provided hints to mutual classification of the DTTs. The study indicates that all DTTs perform as efficiently as the commonly used discrete cosine transform type II - even (DCT IIe) and may be considered as a set of alternative solutions for better watermarking efficiency.

PL

W artykule zaprezentowano wykorzystanie pełnego zestawu 16 dyskretnych transformacji trygonometrycznych (DTT) do efektywnego oznaczania obrazów za pomocą znaków wodnych tworzonych w dziedzinie transformaty. Zaproponowano technikę bazującą na transformacji całego obrazu, przy czym znak wodny umieszczano w części pola transformaty. Opisano korzystne cechy takiego rozwiązania w połączeniu z rodziną DTT. Do weryfikacji efektywności proponowanej techniki oraz transformacji DTT wybrano dwa podstawowe sposoby ataku: filtrację gaussowską oraz kodowanie JPEG. Zbadano także problem, gdy do generowania znaku wodnego jest użyta inna transformacja niż do jego odtworzenia, uzyskując wskazanie do opracowania względnej klasyfikacji rodziny DTT. Przeprowadzone badania wykazały, że wszystkie transformacje DTT są równie efektywne jak parzysta dyskretna transformacja kosinusowa typu II (DCT IIe) i mogą być traktowane jako zbiór alternatywnych propozycji w celu poprawy efektywności oznakowania.