Michael Strintzis | Aristotle University of Thessaloniki (original) (raw)

Papers by Michael Strintzis

In this paper, a novel watermarking scheme able to resist geometric attacks is analyzed. The prop... more In this paper, a novel watermarking scheme able to resist geometric attacks is analyzed. The proposed method performs watermarking of images in the raw domain. A perceptual model is used in order to define the strength of the embedded watermark. For resistance to scaling and rotation attacks, two generalized Radon transformations of the image are introduced, while resistance to translation

Virtual reality, archeology, and cultural heritage, 2004

Proceedings Computer Graphics International 2000, 2000

A novel procedure for segmenting a set of scattered 3-D data obtained from a head and shoulders m... more A novel procedure for segmenting a set of scattered 3-D data obtained from a head and shoulders multiview sequence is presented. The procedure consists of two steps. In the first step, two ellipses corresponding to the head and the body of the person are identified based on ellipse fitting of the outline of the person in each image. The fitting is based on a fast direct least squares method using the constraint that forces a general conic to be an ellipse. In order to achieve head/body segmentation, a K-means algorithm is used to minimise the fitting error between the points and the two ellipsoids. In the second step, a 3-D ellipsoid model corresponding to the head of the person is identified using an extension of the above method. Robustness

2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628), 2002

... D. Simitopoulos&#x27;i2, D. Koutsonanos2 and M. G. Strintzis1&gt;2 &#... more ... D. Simitopoulos&#x27;i2, D. Koutsonanos2 and M. G. Strintzis1&gt;2 &#x27;Aristotle University of Thessaloniki, 54006 Thessaloniki, Greece 21nformatics and Telematics Institute, PO Box 361, 57001 Thermi-Thessaloniki, Greece {dsim,koutsona,strintzi}@iti.gr ...

Eurasip Journal on Advances in Signal Processing, 2004

A novel technique is proposed for watermarking of MPEG-1 and MPEG-2 compressed video streams. The... more A novel technique is proposed for watermarking of MPEG-1 and MPEG-2 compressed video streams. The proposed scheme is applied directly in the domain of MPEG-1 system streams and MPEG-2 program streams (multiplexed streams). Perceptual models are used during the embedding process in order to avoid degradation of the video quality. The water- mark is detected without the use of the

In this paper, a new technique for watermarking of MPEG compressed video streams is proposed. The... more In this paper, a new technique for watermarking of MPEG compressed video streams is proposed. The watermarking scheme operates directly in the domain of MPEG multiplexed streams. Perceptual models are used during the embedding process in order to preserve the quality of the video. The watermark is embedded in the compressed domain and is detected without the use of the

Workshop on Digital and Computational Video, 2001

A new technique for watermarking of MPEG-1/2 compressed video streams is proposed. The watermarki... more A new technique for watermarking of MPEG-1/2 compressed video streams is proposed. The watermarking scheme operates directly in the domain of MPEG-1/2 program streams. Perceptual models are used during the embedding process in order to preserve the quality of the video. The detection of the watermark is performed in the compressed domain without requiring the original video. The resulting watermarking

6th Seminar on Neural Network Applications in Electrical Engineering, 2002

The objective of this paper is to present an experience in the challenge of using Internet and mo... more The objective of this paper is to present an experience in the challenge of using Internet and mobile Internet technologies for the development of a Web/WAP (Wireless Application Protocol)-based medical application with Data Mining support. This medical application is focused on the development, diffusion and use of the technology in response to specific domain needs of medical experts in the area of Cardiology, especially for the patients after by-pass operation.

Biomedical Engineering, 1998

A supervised neural network (NN)-based algorithm was used for automated detection of ischemic epi... more A supervised neural network (NN)-based algorithm was used for automated detection of ischemic episodes resulting from ST segment elevation or depression. The performance of the method was measured using the European ST-T database. In particular, the performance was measured in terms of beat-by-beat ischemia detection and in terms of the detection of ischemic episodes. The algorithm used to train the NN was an adaptive backpropagation (BP) algorithm. This algorithm drastically reduces training time (tenfold decrease in our case) when compared to the classical BP algorithm. The recall phase of the NN is then extremely fast, a fact that makes it appropriate for real-time detection of ischemic episodes. The resulting NN is capable of detecting ischemia independent of the lead used. It was found that the average ischemia episode detection sensitivity is 88.62% while the ischemia duration sensitivity is 72.22%. The results show that NN can be used in electrocardiogram (ECG) processing in cases where fast and reliable detection of ischemic episodes is desired as in the case of critical care units (CCU's).

Computers in Cardiology 1995, 1995

This work provides a semi-automatic method for defining and modeling of the infarcted myocardial ... more This work provides a semi-automatic method for defining and modeling of the infarcted myocardial tissue in MRI images. A deformable contour model based on Fourier decomposition is used to define the border of the infarcted region in successive slice images. A new fast algorithm has been developed for fitting the curve to the borders of the region. The method includes

Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1992

Ischemie changes of the ECG have been detected using the Counterpropagation (CPN), neural network... more Ischemie changes of the ECG have been detected using the Counterpropagation (CPN), neural network. The abnormalities it was trained to detect are T wave elevation, T wave depression, ST segment elevation and ST segment depression. Data for the training of the neural network and for the evaluation of the results are taken from the European ST-T Database.

Proceedings Computers in Cardiology, 1992

A supervised neural network (NN) based algorithm was used to detect ischemic episodes from electr... more A supervised neural network (NN) based algorithm was used to detect ischemic episodes from electrocardiograms (ECGs). The algorithm is tested on the European ST-T database. The algorithm is very fast in its recall state due to the NN, and uses the minimum amount of information, since it is applied on a one-lead ECG. The adaptive training backpropagation algorithm reduces dramatically

Computers in Cardiology 1997, 1997

A deformable 4D model based on Fourier decomposition is presented which was successfully applied ... more A deformable 4D model based on Fourier decomposition is presented which was successfully applied to the modeling of the cardiac endocardial and epicardial surfaces and their deformation in time. The proposed method automatically selects boundary points on the myocardial surfaces in the 3D space, collecting a different set of points for each phase. A 4D model is then fitted to

Computer Vision Theory and Applications, 2007

17th IEEE International Multi Topic Conference 2014, 2014

In this paper, four individual approaches to region classification for knowledge-assisted semanti... more In this paper, four individual approaches to region classification for knowledge-assisted semantic image analysis are presented and comparatively evaluated. All of the examined approaches realize knowledge-assisted analysis via implicit knowledge acquisition, i.e. are based on machine learning techniques such as Support Vector Machines (SVMs), Self Organizing Maps (SOMs), Genetic Algorithm (GA) and Particle Swarm Optimization (PSO). Under all examined approaches, each image is initially segmented and suitable low-level descriptors are extracted for every resulting segment. Then, each of the aforementioned classifiers is applied to associate every region with a predefined high-level semantic concept. An appropriate evaluation framework has been employed for the comparative evaluation of the above algorithms under varying experimental conditions.

IEEE International Conference on Image Processing 2005, 2005

In this paper a 3D shape-based approach is presented for the efficient search, retrieval and clas... more In this paper a 3D shape-based approach is presented for the efficient search, retrieval and classification of protein molecules. The method relies on the geometric 3D appearance of the proteins, which is produced from the corresponding PDB files. After proper positioning and alignment of the 3D structures, in terms of translation and scaling, the 3D structures are decomposed into planes.

IEEE 6th Workshop on Multimedia Signal Processing, 2004., 2004

This paper presents a novel approach in 3D content-based search and retrieval. First, a set of fu... more This paper presents a novel approach in 3D content-based search and retrieval. First, a set of functional are applied on a 3D model&amp;#39;s volume producing a new domain of concentric spheres. In this new domain a new set of functionals is applied, resulting to a completely rotation invariant descriptor vector, which is used for 3D model matching. Experiments were performed

2004 International Conference on Image Processing, 2004. ICIP '04., 2004

A novel method for the watermarking of 3D models is proposed, which is robust to geometric distor... more A novel method for the watermarking of 3D models is proposed, which is robust to geometric distortions such its rotation, translation and uniform scaling. After proper positioning and alignment of the 3D models, a watermark is embedded in the vertices of the model using a robust technique for modifying imperceptibly the location of a subset of the 3D model vertices.

Proceedings 1998 International Conference on Image Processing. ICIP98 (Cat. No.98CB36269), 1998

First Joint Eurohaptics Conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems, 2005

The present paper proposes an efficient collision detection algorithm suitable for use in haptic ... more The present paper proposes an efficient collision detection algorithm suitable for use in haptic applications. The method exploits the fact that the virtual hand can be modelled once and then be used in a variety of applications. In particular, it models each segment of the virtual hand using superquadrics. In order to resolve collision queries the only test that has to be performed is the evaluation of the superquadric inside outside function for each superquadric segment. Experimental evaluation illustrates that the proposed method is extremely fast when compared to standard mesh based approaches. Moreover, it is more realistic and provides the possibility of resolving collision queries for the whole hand and not only for the fingertips, which is the case for methods using spheres at the fingertips in order to perform collision detection. The force feedback provided to the user through the haptic devices is directly evaluated using the analytical formulae of the superquadrics. Finally, two virtual reality applications, which use the proposed method are presented. Results have shown that the algorithm performed accurately and robustly.