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Manos Papadakis

Bio: Manos Papadakis is an academic researcher from University of Houston. The author has contributed to research in topics: Wavelet & Multiresolution analysis. The author has an hindex of 15, co-authored 69 publications receiving 772 citations. Previous affiliations of Manos Papadakis include University of Ioannina & National and Kapodistrian University of Athens.


Papers
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Journal ArticleDOI
TL;DR: A novel framework for quantifying physiological stress at a distance via thermal imaging that associates high stress levels with novice surgeons, while low stress levels are associated with experienced surgeons, raising the possibility for an affective measure (stress) to assist in efficacy determination.
Abstract: In this paper, we present a novel framework for quantifying physiological stress at a distance via thermal imaging. The method captures stress-induced neurophysiological responses on the perinasal area that manifest as transient perspiration. We have developed two algorithms to extract the perspiratory signals from the thermophysiological imagery. One is based on morphology and is computationally efficient, while the other is based on spatial isotropic wavelets and is flexible; both require the support of a reliable facial tracker. We validated the two algorithms against the clinical standard in a controlled lab experiment where orienting responses were invoked on n=18 subjects via auditory stimuli. Then, we used the validated algorithms to quantify stress of surgeons (n=24) as they were performing suturing drills during inanimate laparoscopic training. This is a field application where the new methodology shines. It allows nonobtrusive monitoring of individuals who are naturally challenged with a task that is localized in space and requires directional attention. Both algorithms associate high stress levels with novice surgeons, while low stress levels are associated with experienced surgeons, raising the possibility for an affective measure (stress) to assist in efficacy determination. It is a clear indication of the methodology's promise and potential.

111 citations

Journal ArticleDOI
TL;DR: A general mathematical theory for lifting frames is presented that allows us to modify existing filters to construct new ones that form Parseval frames, and a new image denoising algorithm is proposed, tailored to the specific properties of these new frame filters.
Abstract: We present a general mathematical theory for lifting frames that allows us to modify existing filters to construct new ones that form Parseval frames. We apply our theory to design nonseparable Parseval frames from separable (tensor) products of a piecewise linear spline tight frame. These new frame systems incorporate the weighted average operator, the Sobel operator, and the Laplacian operator in directions that are integer multiples of 45/spl deg/. A new image denoising algorithm is then proposed, tailored to the specific properties of these new frame filters. We demonstrate the performance of our algorithm on a diverse set of images with very encouraging results.

65 citations

Journal ArticleDOI
TL;DR: The main results are the characterization of IMRAs in terms of the Lax–Wiener Theorem, and the characterization and application of IMRA wavelets to 2D and 3D-texture segmentation in natural and biomedical images.
Abstract: In this paper we investigate Isotropic Multiresolution Analysis (IMRA), isotropic refinable functions, and wavelets. The main results are the characterization of IMRAs in terms of the Lax–Wiener Theorem, and the characterization of isotropic refinable functions in terms of the support of their Fourier transform. As an immediate consequence of these results, there are no compactly supported (in the space domain) isotropic refinable functions in many dimensions. Next we study the approximation properties of IMRAs. Finally, we discuss the application of IMRA wavelets to 2D and 3D-texture segmentation in natural and biomedical images.

53 citations

Journal ArticleDOI
TL;DR: A novel representation, the Minimum Shape-Cost (MSC) Tree, is introduced that approximates the dendrite centerline with sub-voxel accuracy and is demonstrated to be the uniqueness of such a shape representation as well as its computational efficiency.
Abstract: The challenges faced in analyzing optical imaging data from neurons include a low signal-to-noise ratio of the acquired images and the multiscale nature of the tubular structures that range in size from hundreds of microns to hundreds of nanometers. In this paper, we address these challenges and present a computational framework for an automatic, three-dimensional (3D) morphological reconstruction of live nerve cells. The key aspects of this approach are: (i) detection of neuronal dendrites through learning 3D tubular models, and (ii) skeletonization by a new algorithm using a morphology-guided deformable model for extracting the dendritic centerline. To represent the neuron morphology, we introduce a novel representation, the Minimum Shape-Cost (MSC) Tree that approximates the dendrite centerline with sub-voxel accuracy and demonstrate the uniqueness of such a shape representation as well as its computational efficiency. We present extensive quantitative and qualitative results that demonstrate the accuracy and robustness of our method.

48 citations

Proceedings ArticleDOI
18 Mar 2005
TL;DR: A general mathematical theory for lifting frames is presented that allows us to modify existing filters to construct new ones that form Parseval frames, and a new image denoising algorithm is proposed, tailored to the specific properties of these new frame filters.
Abstract: We present a general mathematical theory for lifting frames that allows us to modify existing filters to construct new ones that form Parseval frames. We apply our theory to design non-separable Parseval frames from separable (tensor) products of a piecewise linear spline tight frame. These new frame systems incorporate the weighted average operator and the Sobel operator in directions that are integer multiples of 45/spl deg/. A new image denoising algorithm is then proposed tailored to the specific properties of these new frame filters. We demonstrate the performance of our algorithm on a diverse set of images with very encouraging results.

42 citations


Cited by
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01 Jan 2006

3,012 citations

Proceedings Article
01 Jan 1989
TL;DR: A scheme is developed for classifying the types of motion perceived by a humanlike robot and equations, theorems, concepts, clues, etc., relating the objects, their positions, and their motion to their images on the focal plane are presented.
Abstract: A scheme is developed for classifying the types of motion perceived by a humanlike robot. It is assumed that the robot receives visual images of the scene using a perspective system model. Equations, theorems, concepts, clues, etc., relating the objects, their positions, and their motion to their images on the focal plane are presented. >

2,000 citations

Journal ArticleDOI
TL;DR: This paper presents the computational tools and a hardware prototype for 3D face recognition and presents the results on the largest known, and now publicly available, face recognition grand challenge 3D facial database consisting of several thousand scans.
Abstract: In this paper, we present the computational tools and a hardware prototype for 3D face recognition. Full automation is provided through the use of advanced multistage alignment algorithms, resilience to facial expressions by employing a deformable model framework, and invariance to 3D capture devices through suitable preprocessing steps. In addition, scalability in both time and space is achieved by converting 3D facial scans into compact metadata. We present our results on the largest known, and now publicly available, face recognition grand challenge 3D facial database consisting of several thousand scans. To the best of our knowledge, this is the highest performance reported on the FRGC v2 database for the 3D modality

496 citations

Posted Content
TL;DR: In this paper, it was shown that the relation between a frame and its local components leads to the definition of a frame of subspaces, which is a generalization of frames.
Abstract: One approach to ease the construction of frames is to first construct local components and then build a global frame from these. In this paper we will show that the study of the relation between a frame and its local components leads to the definition of a frame of subspaces. We introduce this new notion and prove that it provides us with the link we need. It will also turn out that frames of subspaces behave as a generalization of frames. In particular, we can define an analysis, a synthesis and a frame operator for a frame of subspaces, which even yield a reconstruction formula. Also concepts such as completeness, minimality, and exactness are introduced and investigated. We further study several constructions of frames of subspaces, and also of frames and Riesz frames using the theory of frames of subspaces. An important special case are harmonic frames of subspaces which generalize harmonic frames. We show that wavelet subspaces coming from multiresolution analysis belong to this class.

386 citations

01 Jan 1998
TL;DR: A comprehensive list of papers that use the Self-Organizing Map algorithms, have bene ted from them, or contain analyses of them is collected and provided both a thematic and a keyword index to help find articles of interest.
Abstract: The Self-Organizing Map (SOM) algorithm has attracted an ever increasing amount of interest among researches and practitioners in a wide variety of elds The SOM and a variant of it, the LVQ, have been analyzed extensively, a number of variants of them have been developed and, perhaps most notably, they have been applied extensively within elds ranging from engineering sciences to medicine, biology, and economics We have collected a comprehensive list of 3343 scienti c papers that use the algorithms, have bene ted from them, or contain analyses of them The list is intended to serve as a source for literature surveys We have provided both a thematic and a keyword index to help nding articles of interest

331 citations