V. Fotopoulos

Hellenic Open University

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Athanassios Skodras

University of Patras

Anastasios Fanariotis

University of West Attica

‪O

‪Theofanis Orphanoudakis‬

University of West Attica

Bill Vassiliadis

Hellenic Open University

Eleni E. Varsaki

Hellenic Open University

Argyro Sgourou

Hellenic Open University

E. Chrysochos

Hellenic Open University

Vasiliki Chondrou

Hellenic Open University

Michalis Xenos

University of Patras

Theodora Kouvara

Hellenic Open University

Cooperative Institutions

University of Patras

Hellenic Open University

National and Kapodistrian University of Athens

University of Florence

Aristotle University of Thessaloniki

General University Hospital of Patras

Research Academic Computer Technology Institute

University of Florida

University of Palermo

University of Ioannina

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A Digital Rights Management System and Copyright Protection for Digital Images of the Official Web Portal of the Hellenic Culture

Springer eBooks (2003)

Dimitrios Tsolis V. Fotopoulos George K. Tsolis Emmanouil G. Karatzas Spiros Nikolopoulos

Digital rights management

Christian ministry

10.1007/978-1-4615-0381-1_19

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Citations (0)

A new difference expansion transform in triplets for reversible data hiding

International Journal of Computer Mathematics (2011)

E. Chrysochos V. Fotopoulos Athanassios Skodras

Difference expansion (DE) has been widely used for reversible data hiding. In this paper, a novel transform which embeds two bits of information in a triplet of coefficients is presented. This transform can be applied in spatial or frequency domains and induces minimum distortion to the initial data or coefficients. The proposed method outperforms all similar DE methods using triplets in terms of computational cost, visual quality and bitrate.

Distortion (music)

10.1080/00207160.2010.539210

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Citations (4)

Watermarking and Authentication in JPEG2000

IGI Global eBooks (2011)

V. Fotopoulos Ioannis Kostopoulos

This chapter introduces JPEG 2000 as an application field for image authentication and the new technology of digital image watermarking. The new compression format has many unexplored characteristics that both the watermarking and the authentication communities should carefully take into account. Thus, a brief introduction to the standard is given at the beginning, discussing its structure, features, novelties, and capabilities. Following that introduction, watermarking techniques are presented, at first into the wavelet domain (the DWT is part of the JPEG2000 core), and then into the JPEG 2000 pipeline. The effects of the various standards' parameters in this process are carefully investigated. Then, authentication mechanisms of JPEG 2000 images are described and we peek into JPSEC, part-8 of JPEG 2000 that deals with issues of watermarking and authentication. Request access from your librarian to read this chapter's full text.

JPEG 2000

10.4018/9781605661186.ch005

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JPEG2000 parameters against watermarking

V. Fotopoulos Athanassios Skodras

In the paper, the effects of the imminent JPEG2000 compression standard on watermarking techniques are investigated. It is shown that the choice of different coding parameters affects the performance of transform domain watermarking techniques. Compression ratio is of course important but not the only parameter that a watermarking scheme should take into account.

JPEG 2000

10.1109/icdsp.2002.1028190

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Citations (1)

Author response for "Epigenetic/genetic variations in CG‐rich elements of immune‐related genes contribute to food allergy development during childhood"

Maria Kostara Vasiliki Chondrou V. Fotopoulos Argyro Sgourou Sophia Tsabouri

10.1111/pai.13812/v2/response1

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Low bit depth representation motion estimation algorithms: a comparative study

Journal of Real-Time Image Processing (2009)

A. Vlachos V. Fotopoulos Athanassios Skodras

Bit (key)

10.1007/s11554-009-0130-4

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Citations (5)

Hybrid watermarking based on chaos and histogram modification

Signal Image and Video Processing (2012)

E. Chrysochos V. Fotopoulos Michalis Xenos Athanassios Skodras

Robustness

10.1007/s11760-012-0307-3

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Citations (25)

LEVERAGING THE INTERNET OF THINGS TOWARDS RAISING ENVIRONMENTAL AWARENESS IN EUROPEAN CLASSROOMS

ICERI proceedings (2022)

Theodora Kouvara Anastasios Fanariotis V. Fotopoulos ‪Christoforos Karachristos ‪Theofanis Orphanoudakis‬

Appears in: ICERI2022 Proceedings Publication year: 2022Pages: 5195-5202ISBN: 978-84-09-45476-1ISSN: 2340-1095doi: 10.21125/iceri.2022.1265Conference name: 15th annual International Conference of Education, Research and InnovationDates: 7-9 November, 2022Location: Seville, Spain

Raising (metalworking)

10.21125/iceri.2022.1265

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Citations (0)

<title>Transform domain watermarking: adaptive selection of the watermark's position and length</title>

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2003)

V. Fotopoulos Athanassios Skodras

Transform domain methods have dominated the watermarking field from its early stages. In these methods some coefficients are selected and modified according to certain rules. The two most important numbers in this process are the length and the position of the watermark. These are usually heuristically chosen. In order to handle this problem, an adaptive scheme for the selection of the proper coefficients is analysed in the present communication.

Position (finance)

10.1117/12.505903

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Citations (9)

On the use of the discrete Pascal transform in hiding data in images

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE (2010)

Eleni E. Varsaki V. Fotopoulos Athanassios Skodras

The Discrete Pascal Transform (DPT) has been proved remarkably useful for edge detection, filter design, discrete-time signal interpolation and data hiding. In the present work a new blind fragile data hiding technique for secretly embedding messages into color images, is proposed. The embedding procedure is based on dividing each color image component into even-sized blocks. Information embedding is determined by monitoring the lower-right corner of the DPT coefficient matrix. This particular coefficient suffers the highest change for small pixel modifications. The embedding affects the coefficient's sign. In case that the sign is not the desired one, i.e. negative for a message bit value of '0' and positive for a message bit value of '1', it is changed by repeatedly adding to the block or subtracting from the block the identity matrix. This process is based on the DPT properties and on the sensitivity of the lower-right coefficient in even the smallest pixel changes. The embedding algorithm takes care of the underflows or overflows that may occur during the consecutive additions or subtractions. The method is evaluated in terms of capacity and image distortion. Experiments are conducted using different images and block sizes namely 2x2 / 4x4 / 8x8 / 16x16, and the overall performance of the scheme is quantified. Block size greatly affects capacity and stego-image quality. Comparisons with existing methods prove the superiority of the proposed method.

Coefficient matrix

Pascal (unit)

Peak signal-to-noise ratio

Block size

10.1117/12.854220

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Citations (15)