An Empirical Comparison of SNoW and SVMs for Face Detection

Impressive claims have been made for the performance of the SNoW algorithm on face detection tasks by Yang et. al. [7]. In particular, by looking at both their results and those of Heisele et. al. [3], one could infer that the SNoW system performed substantially better than an SVM-based system, even when the SVM used a polynomial kernel and the SNoW system used a particularly simplistic 'primitive' linear representation. We evaluated the two approaches in a controlled experiment, looking directly at performance on a simple, fixed-sized test set, isolating out 'infrastructure' issues related to detecting faces at various scales in large images. We found that SNoW performed about as well as linear SVMs, and substantially worse than polynomial SVMs.

Face Detection in Still Gray Images

We present a trainable system for detecting frontal and near-frontal views of faces in still gray images using Support Vector Machines (SVMs). We first consider the problem of detecting the whole face pattern by a single SVM classifer. In this context we compare different types of image features, present and evaluate a new method for reducing the number of features and discuss practical issues concerning the parameterization of SVMs and the selection of training data. The second part of the paper describes a component-based method for face detection consisting of a two-level hierarchy of SVM classifers. On the first level, component classifers independently detect components of a face, such as the eyes, the nose, and the mouth. On the second level, a single classifer checks if the geometrical configuration of the detected components in the image matches a geometrical model of a face.

Feature Selection for Face Detection

We present a new method to select features for a face detection system using Support Vector Machines (SVMs). In the first step we reduce the dimensionality of the input space by projecting the data into a subset of eigenvectors. The dimension of the subset is determined by a classification criterion based on minimizing a bound on the expected error probability of an SVM. In the second step we select features from the SVM feature space by removing those that have low contributions to the decision function of the SVM.

Role of color in face recognition

One of the key challenges in face perception lies in determining the contribution of different cues to face identification. In this study, we focus on the role of color cues. Although color appears to be a salient attribute of faces, past research has suggested that it confers little recognition advantage for identifying people. Here we report experimental results suggesting that color cues do play a role in face recognition and their contribution becomes evident when shape cues are degraded. Under such conditions, recognition performance with color images is significantly better than that with grayscale images. Our experimental results also indicate that the contribution of color may lie not so much in providing diagnostic cues to identity as in aiding low-level image-analysis processes such as segmentation.

Relative Contributions of Internal and External Features to Face Recognition

The central challenge in face recognition lies in understanding the role different facial features play in our judgments of identity. Notable in this regard are the relative contributions of the internal (eyes, nose and mouth) and external (hair and jaw-line) features. Past studies that have investigated this issue have typically used high-resolution images or good-quality line drawings as facial stimuli. The results obtained are therefore most relevant for understanding the identification of faces at close range. However, given that real-world viewing conditions are rarely optimal, it is also important to know how image degradations, such as loss of resolution caused by large viewing distances, influence our ability to use internal and external features. Here, we report experiments designed to address this issue. Our data characterize how the relative contributions of internal and external features change as a function of image resolution. While we replicated results of previous studies that have shown internal features of familiar faces to be more useful for recognition than external features at high resolution, we found that the two feature sets reverse in importance as resolution decreases. These results suggest that the visual system uses a highly non-linear cue-fusion strategy in combining internal and external features along the dimension of image resolution and that the configural cues that relate the two feature sets play an important role in judgments of facial identity.

Face processing in humans is compatible with a simple shape-based model of vision

Understanding how the human visual system recognizes objects is one of the key challenges in neuroscience. Inspired by a large body of physiological evidence (Felleman and Van Essen, 1991; Hubel and Wiesel, 1962; Livingstone and Hubel, 1988; Tso et al., 2001; Zeki, 1993), a general class of recognition models has emerged which is based on a hierarchical organization of visual processing, with succeeding stages being sensitive to image features of increasing complexity (Hummel and Biederman, 1992; Riesenhuber and Poggio, 1999; Selfridge, 1959). However, these models appear to be incompatible with some well-known psychophysical results. Prominent among these are experiments investigating recognition impairments caused by vertical inversion of images, especially those of faces. It has been reported that faces that differ "featurally" are much easier to distinguish when inverted than those that differ "configurally" (Freire et al., 2000; Le Grand et al., 2001; Mondloch et al., 2002) ??finding that is difficult to reconcile with the aforementioned models. Here we show that after controlling for subjects' expectations, there is no difference between "featurally" and "configurally" transformed faces in terms of inversion effect. This result reinforces the plausibility of simple hierarchical models of object representation and recognition in cortex.

Face and content validity of smoking-related and matched control pictures

Smoking-related pictures and matched controls are useful tools in experimental tasks of attentional bias. Noteworthy the procedures used to produce and validate these pairs of pictures are poorly reported. This study aimed to describe the production and evidence of validity of a set of smoking-related pictures and their matched controls. Two studies were conducted to assess validity. An online internet-based survey was used to assess face validity of 12 pictures related to smoking behavior and 12 matched controls. All pictures were colored and were 95mm length x 130mm width. Participants were asked if the pictures were related or not to the smoking behavior and also rated how much each picture was related to smoking behavior. The second study investigated attentional bias in smokers (n = 47) and non-smokers (n = 50), and examined how they assessed all pictures in terms of pleasantness and the 12 smoking-related pictures in terms of relevance to their own smoking behavior. Craving was assessed before and after the experiment. Results indicate that this set of pictures are valid since smoking-related pictures were considered more related to smoking behavior compared to their matched controls. Moreover, smokers showed greater attentional bias for smoking-related pictures than non-smokers. Craving and relevance of the smoking-related pictures were higher in smokers than in non-smokers. Smokers considered smoking-related pictures them less unpleasant than non-smokers. These findings provide evidence of face and content validity of this set of pictures, which will be available to researchers, contributing to maximize the standardization of future investigations.

My face. 'Mi cara'.

Se trata de una unidad didáctica que pretende que el alumno tenga un conocimiento de las partes de la cara, y que a través de la lectura y de juegos en clase conseguir dominar ciertas formas de expresión y vocabulario en lengua inglesa.

At the centre of the Bologna process : do European universities train their students to face knowledge based societies?. 'En el centro del proceso de Bolonia: ¿entrenan las universidades europeas a sus estudiantes para enfrentarse a sociedades basadas en el conocimiento?'.

Resumen tomado de la publicación. Monográfico con el título: El proceso de Bolonia : dinámicas y desafíos de la enseñanza superior en Europa a comienzos de una nueva época

The human face of globalization : implications in education.

Resumen tomado del autor

The North face of Shakespeare : activities for teaching the plays.

Libro dirigido a profesores de literatura inglesa y arte dramático, tanto en educación secundaria como en la universidad, para la enseñanza de las obras del dramaturgo inglés William Shakespeare con métodos activos en clase y en talleres de teatro. Contiene alrededor de doscientas actividades para la enseñanza de los textos de Shakespeare, desde la formación de grupos de trabajo, juegos y ejercicios teatrales, a técnicas prácticas para la enseñanza del lenguaje, la narrativa y los personajes del autor, que ayudarán a los alumnos a leer, entender y trabajar con su obra.

As atitudes dos educadores de infáncia face à integraçao das crianças em situaçáo de risco.

Trata el tema de las necesidades que encuentra el profesorado de educación infantil ante la integración de niños en situación de riesgo. Se hace eco de las iniciativas tomadas por algunos educadores y denuncia las necesidades que tiene el profesorado ante esta situación, para los que solicita formación y preparación.

Educação para os media : uma aposta urgente e necessária face aos novos media. 'Educación para los media : una apuesta urgente y necesaria de cara a los nuevos media'.

El artículo forma parte de un monográfico de la revista dedicado a una televisión de calidad.- Resumen tomado parcialmente de la revista

As representaçoes das famílias dos jovens com deficiencia mental face a filosofia da educaçao inclusiva. 'La representación de las familias de los jóvenes con deficiencia mental hacen frente a la filosofía de la educación inclusiva'.

El modelo educativo presente en los equipos de Educación Especial, que centra su atención en el profesor y este en su alumno, da lugar a un modelo que acentúa la necesidad de ayuda que se presta a los profesores para colaborar en la mejora de las condiciones objetivas del entorno y educación de los alumnos. El objetivo fundamental es conocer y analizar las opciones de las personas a cargo de jóvenes con deficiencia mental y hacer frente a la idea de la escuela inclusiva. Se pretende estudiar las necesidades reales de las familias a cargo de estos jóvenes y si se cumplen las expectativas que poseen en relación a sus escuelas, estimar el nivel de colaboración de las familias y la escuela inclusiva. En la primera parte, se presenta el marco teórico de la investigación, donde se estudian los sistemas familiares, su estructura, funciones, factores de estrés y la unión familia-escuela. Se abordan los principios fundamentales del concepto de Educación Especial en las últimas décadas y el marco legislativo concreto de la Educación Especial portuguesa. La segunda parte del estudio se centra en el modelo de investigación cualitativa utilizado. La muestra está formada por 15 familias portuguesas del Concejo de Miranda do Douro con hijos con deficiencia mental y que van a escuelas de segundo y tercer ciclo de Enseñanza Básica. A cada una de estas familias se le realiza una entrevista estructurada y en profundidad centrándose en la actual situación de la escuela y la inclusión de jóvenes con deficiencia mental. En general, la relación establecida entre la familia frente a la escolarización cuando se trata de jóvenes con deficiencia mental no implica ningún aspecto problemático. En principio ante esta situación de normalidad tanto para los padres como para los profesores hay que prestar atención a la preocupación natural en lo referente al momento actual que se vive en la escuela y a la ansiedad e inquietud en el futuro aprendizaje de los niños con deficiencia mental. La organización y correcto funcionamiento de la escuela y la participación colectiva es fundamental para conseguir que los alumnos asuman positivamente su escolarización. Reconcen que la escuelas carecen de un nivel de recursos humanos especializados y materiales específicos, en concreto la carencia de profesores de Educación Especial, psicólogos y otros técnicos. Se observa que los padres valoran el aprendizaje de sus hijos y que puede ser en muchos casos condicionante para la dedicación que reciben de sus padres. Incentivan y favorecen la autoestima mediante elogios, y demuestran tener paciencia ante las limitaciones de aprendizaje de sus hijos. Ayudan cuando es necesario o cuando el joven exige atención, porque la ayuda puede estimular a la responsabilización en la elaboración de tareas.

Identi???cation of degrees of anxiety in children with three- and ???ve-face facial scales

Resumen tomado de la publicaci??n