Ioannis Pitas

Bio: Ioannis Pitas is an academic researcher from Aristotle University of Thessaloniki. The author has contributed to research in topics: Facial recognition system & Digital watermarking. The author has an hindex of 76, co-authored 795 publications receiving 24787 citations. Previous affiliations of Ioannis Pitas include University of Bristol & University of York.

Computational UAV Cinematography for Intelligent Shooting Based on Semantic Visual Analysis

Abstract: Audiovisual coverage of sports events using Unmanned Aerial Vehicles (UAVs) is becoming increasingly popular. Intelligent audiovisual (A/V) shooting tools, accurately identifying the 2D region of cinematographic attention (RoCA) depicting rapidly moving target ensembles and automatically controlling the UAVs/cameras through visual content analysis, are thus needed. A novel algorithmic pipeline is proposed, implementing computational UAV cinematography for assisting sports coverage, based on semantic, human-centered visual analysis. Athlete and ball detection / tracking results as well as their spatial distribution on the image plane are the semantic features extracted from UAV video feed and exploited for RoCA extraction, based solely on present and past target detections. A PID controller visually controlling a real or virtual camera to track the RoCA and produce aesthetically pleasing shots, without exploiting 3D location-related information, is employed. The proposed method is evaluated on actual UAV footage from soccer matches and promising results are obtained.

Frontal face detection using support vector machines and back-propagation neural networks

Abstract: Face detection is a key problem in building systems that perform face recognition/verification and model-based image coding. Two algorithms for face detection that employ either support vector machines or backpropagation feedforward neural networks are described, and their performance is tested on the same frontal face database using the false acceptance and false rejection rates as quantitative figures of merit. The aforementioned algorithms can replace the explicitly-defined knowledge for facial regions and facial features in mosaic-based face detection algorithms.

Face Authentication Using Morphological Dynamic Link Architecture

Abstract: A very attractive approach for face detection is based on multiresolution images (also known as mosaic images). Motivated by the simplicity of this approach, a rule-based face detection algorithm in frontal views is developed first. Second, a novel dynamic link architecture based on multiscale morphological dilation-erosion is proposed for face authentication. More specifically, a sparse grid is placed over the outcome of face detection stage for each person in a reference set. Subsequently, multiscale morphological operations are employed to yield a feature vector at each node of the grid and dynamic link matching is applied to verify the identity of each person from a test set. The first experimental results reported in this paper verify the superiority of the proposed method over the (standard) dynamic link matching that is based on Gabor wavelets.

One class classification applied in facial image analysis

Abstract: In this paper, we apply One-Class Classification methods in facial image analysis problems. We consider the cases where the available training data information originates from one class, or one of the available classes is of high importance. We propose a novel extension of the One-Class Extreme Learning Machines algorithm aiming at minimizing both the training error and the data dispersion and consider solutions that generate decision functions in the ELM space, as well as in ELM spaces of arbitrary dimensionality. We evaluate the performance in publicly available datasets. The proposed method compares favourably to other state-of-the-art choices.

A Mutual Information based Face Clustering Algorithm for Movies

Abstract: In this paper a new approach for face clustering is developed. Mutual information and joint entropy are exploited in order to create a metric for the clustering process. The way the joint entropy and the mutual information are calculated gives some interesting properties to the aforementioned metric, which guarantees some robustness against standard noisy transformation such as scaling, cropping and pose changes. A slight preprocessing of the input face images is done in order to undertake problems that arise from detector's known errors.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Face recognition: A literature survey

Abstract: As one of the most successful applications of image analysis and understanding, face recognition has recently received significant attention, especially during the past several years. At least two reasons account for this trend: the first is the wide range of commercial and law enforcement applications, and the second is the availability of feasible technologies after 30 years of research. Even though current machine recognition systems have reached a certain level of maturity, their success is limited by the conditions imposed by many real applications. For example, recognition of face images acquired in an outdoor environment with changes in illumination and/or pose remains a largely unsolved problem. In other words, current systems are still far away from the capability of the human perception system.This paper provides an up-to-date critical survey of still- and video-based face recognition research. There are two underlying motivations for us to write this survey paper: the first is to provide an up-to-date review of the existing literature, and the second is to offer some insights into the studies of machine recognition of faces. To provide a comprehensive survey, we not only categorize existing recognition techniques but also present detailed descriptions of representative methods within each category. In addition, relevant topics such as psychophysical studies, system evaluation, and issues of illumination and pose variation are covered.

Detecting faces in images: a survey

Abstract: Images containing faces are essential to intelligent vision-based human-computer interaction, and research efforts in face processing include face recognition, face tracking, pose estimation and expression recognition. However, many reported methods assume that the faces in an image or an image sequence have been identified and localized. To build fully automated systems that analyze the information contained in face images, robust and efficient face detection algorithms are required. Given a single image, the goal of face detection is to identify all image regions which contain a face, regardless of its 3D position, orientation and lighting conditions. Such a problem is challenging because faces are non-rigid and have a high degree of variability in size, shape, color and texture. Numerous techniques have been developed to detect faces in a single image, and the purpose of this paper is to categorize and evaluate these algorithms. We also discuss relevant issues such as data collection, evaluation metrics and benchmarking. After analyzing these algorithms and identifying their limitations, we conclude with several promising directions for future research.