| Records |
| Author |
Gemma Sanchez; Josep Llados; K. Tombre |
Title  |
A mean string algorithm to compute the average among a set of 2D shapes |
Type |
Journal Article |
| Year |
2002 |
Publication |
Pattern Recognition Letters |
Abbreviated Journal |
PRL |
| Volume |
23 |
Issue |
1-3 |
Pages |
203–214 |
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DAG; IF: 0.409 |
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no |
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DAG @ dag @ SLT2002 |
Serial |
275 |
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| Author |
Olivier Penacchio; Xavier Otazu; Arnold J Wilkings; Sara M. Haigh |
| Title |
A mechanistic account of visual discomfort |
Type |
Journal Article |
| Year |
2023 |
Publication |
Frontiers in Neuroscience |
Abbreviated Journal |
FN |
| Volume |
17 |
Issue |
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Pages |
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| Abstract |
Much of the neural machinery of the early visual cortex, from the extraction of local orientations to contextual modulations through lateral interactions, is thought to have developed to provide a sparse encoding of contour in natural scenes, allowing the brain to process efficiently most of the visual scenes we are exposed to. Certain visual stimuli, however, cause visual stress, a set of adverse effects ranging from simple discomfort to migraine attacks, and epileptic seizures in the extreme, all phenomena linked with an excessive metabolic demand. The theory of efficient coding suggests a link between excessive metabolic demand and images that deviate from natural statistics. Yet, the mechanisms linking energy demand and image spatial content in discomfort remain elusive. Here, we used theories of visual coding that link image spatial structure and brain activation to characterize the response to images observers reported as uncomfortable in a biologically based neurodynamic model of the early visual cortex that included excitatory and inhibitory layers to implement contextual influences. We found three clear markers of aversive images: a larger overall activation in the model, a less sparse response, and a more unbalanced distribution of activity across spatial orientations. When the ratio of excitation over inhibition was increased in the model, a phenomenon hypothesised to underlie interindividual differences in susceptibility to visual discomfort, the three markers of discomfort progressively shifted toward values typical of the response to uncomfortable stimuli. Overall, these findings propose a unifying mechanistic explanation for why there are differences between images and between observers, suggesting how visual input and idiosyncratic hyperexcitability give rise to abnormal brain responses that result in visual stress. |
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NEUROBIT |
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no |
| Call Number |
Admin @ si @ POW2023 |
Serial |
3886 |
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| Author |
Ernest Valveny; Enric Marti |
| Title |
A model for image generation and symbol recognition through the deformation of lineal shapes |
Type |
Journal Article |
| Year |
2003 |
Publication |
Pattern Recognition Letters |
Abbreviated Journal |
PRL |
| Volume |
24 |
Issue |
15 |
Pages |
2857-2867 |
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| Abstract |
We describe a general framework for the recognition of distorted images of lineal shapes, which relies on three items: a model to represent lineal shapes and their deformations, a model for the generation of distorted binary images and the combination of both models in a common probabilistic framework, where the generation of deformations is related to an internal energy, and the generation of binary images to an external energy. Then, recognition consists in the minimization of a global energy function, performed by using the EM algorithm. This general framework has been applied to the recognition of hand-drawn lineal symbols in graphic documents. |
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Elsevier Science Inc. |
Place of Publication |
New York, NY, USA |
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0167-8655 |
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DAG; IAM |
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no |
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IAM @ iam @ VAM2003 |
Serial |
1653 |
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| Author |
Judit Martinez; Eva Costa; P. Herreros; F. Javier Sanchez; Ramon Baldrich |
| Title |
A Modular and Scalable Architecture for PC-Based Real-Time Vision Systems |
Type |
Journal Article |
| Year |
2003 |
Publication |
Real–Time Imaging, (IF: 0.512) |
Abbreviated Journal |
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| Volume |
9 |
Issue |
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Pages |
99-112 |
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CIC |
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no |
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CAT @ cat @ MCH2003b |
Serial |
394 |
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| Author |
Guillermo Torres; Debora Gil |
| Title |
A multi-shape loss function with adaptive class balancing for the segmentation of lung structures |
Type |
Journal Article |
| Year |
2020 |
Publication |
International Journal of Computer Assisted Radiology and Surgery |
Abbreviated Journal |
IJCAR |
| Volume |
15 |
Issue |
1 |
Pages |
S154-55 |
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IAM |
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no |
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Admin @ si @ ToG2020 |
Serial |
3590 |
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| Author |
Maria Vanrell; Jordi Vitria; Xavier Roca |
| Title |
A multidimensional scaling approach to explore the behavior of a texture perception algorithm. |
Type |
Journal Article |
| Year |
1997 |
Publication |
Machine Vision and Applications |
Abbreviated Journal |
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| Volume |
9 |
Issue |
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Pages |
262–271 |
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OR;ISE;CIC;MV |
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no |
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BCNPCL @ bcnpcl @ VVR1997 |
Serial |
35 |
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| Author |
Manuel Carbonell; Alicia Fornes; Mauricio Villegas; Josep Llados |
| Title |
A Neural Model for Text Localization, Transcription and Named Entity Recognition in Full Pages |
Type |
Journal Article |
| Year |
2020 |
Publication |
Pattern Recognition Letters |
Abbreviated Journal |
PRL |
| Volume |
136 |
Issue |
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Pages |
219-227 |
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| Abstract |
In the last years, the consolidation of deep neural network architectures for information extraction in document images has brought big improvements in the performance of each of the tasks involved in this process, consisting of text localization, transcription, and named entity recognition. However, this process is traditionally performed with separate methods for each task. In this work we propose an end-to-end model that combines a one stage object detection network with branches for the recognition of text and named entities respectively in a way that shared features can be learned simultaneously from the training error of each of the tasks. By doing so the model jointly performs handwritten text detection, transcription, and named entity recognition at page level with a single feed forward step. We exhaustively evaluate our approach on different datasets, discussing its advantages and limitations compared to sequential approaches. The results show that the model is capable of benefiting from shared features by simultaneously solving interdependent tasks. |
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| Notes |
DAG; 600.140; 601.311; 600.121 |
Approved |
no |
| Call Number |
Admin @ si @ CFV2020 |
Serial |
3451 |
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| Author |
David Berga; Xavier Otazu |
| Title |
A neurodynamic model of saliency prediction in v1 |
Type |
Journal Article |
| Year |
2022 |
Publication |
Neural Computation |
Abbreviated Journal |
NEURALCOMPUT |
| Volume |
34 |
Issue |
2 |
Pages |
378-414 |
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| Abstract |
Lateral connections in the primary visual cortex (V1) have long been hypothesized to be responsible for several visual processing mechanisms such as brightness induction, chromatic induction, visual discomfort, and bottom-up visual attention (also named saliency). Many computational models have been developed to independently predict these and other visual processes, but no computational model has been able to reproduce all of them simultaneously. In this work, we show that a biologically plausible computational model of lateral interactions of V1 is able to simultaneously predict saliency and all the aforementioned visual processes. Our model's architecture (NSWAM) is based on Penacchio's neurodynamic model of lateral connections of V1. It is defined as a network of firing rate neurons, sensitive to visual features such as brightness, color, orientation, and scale. We tested NSWAM saliency predictions using images from several eye tracking data sets. We show that the accuracy of predictions obtained by our architecture, using shuffled metrics, is similar to other state-of-the-art computational methods, particularly with synthetic images (CAT2000-Pattern and SID4VAM) that mainly contain low-level features. Moreover, we outperform other biologically inspired saliency models that are specifically designed to exclusively reproduce saliency. We show that our biologically plausible model of lateral connections can simultaneously explain different visual processes present in V1 (without applying any type of training or optimization and keeping the same parameterization for all the visual processes). This can be useful for the definition of a unified architecture of the primary visual cortex. |
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| Notes |
NEUROBIT; 600.128; 600.120 |
Approved |
no |
| Call Number |
Admin @ si @ BeO2022 |
Serial |
3696 |
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| Author |
Olivier Penacchio; Xavier Otazu; Laura Dempere-Marco |
| Title |
A Neurodynamical Model of Brightness Induction in V1 |
Type |
Journal Article |
| Year |
2013 |
Publication |
PloS ONE |
Abbreviated Journal |
Plos |
| Volume |
8 |
Issue |
5 |
Pages |
e64086 |
| Keywords |
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| Abstract |
Brightness induction is the modulation of the perceived intensity of an area by the luminance of surrounding areas. Recent neurophysiological evidence suggests that brightness information might be explicitly represented in V1, in contrast to the more common assumption that the striate cortex is an area mostly responsive to sensory information. Here we investigate possible neural mechanisms that offer a plausible explanation for such phenomenon. To this end, a neurodynamical model which is based on neurophysiological evidence and focuses on the part of V1 responsible for contextual influences is presented. The proposed computational model successfully accounts for well known psychophysical effects for static contexts and also for brightness induction in dynamic contexts defined by modulating the luminance of surrounding areas. This work suggests that intra-cortical interactions in V1 could, at least partially, explain brightness induction effects and reveals how a common general architecture may account for several different fundamental processes, such as visual saliency and brightness induction, which emerge early in the visual processing pathway. |
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CIC |
Approved |
no |
| Call Number |
Admin @ si @ POD2013 |
Serial |
2242 |
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| Author |
C. Alejandro Parraga; Javier Vazquez; Maria Vanrell |
| Title |
A new cone activation-based natural images dataset |
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Journal Article |
| Year |
2009 |
Publication |
Perception |
Abbreviated Journal |
PER |
| Volume |
36 |
Issue |
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Pages |
180 |
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| Abstract |
We generated a new dataset of digital natural images where each colour plane corresponds to the human LMS (long-, medium-, short-wavelength) cone activations. The images were chosen to represent five different visual environments (eg forest, seaside, mountain snow, urban, motorways) and were taken under natural illumination at different times of day. At the bottom-left corner of each picture there was a matte grey ball of approximately constant spectral reflectance (across the camera's response spectrum,) and nearly Lambertian reflective properties, which allows to compute (and remove, if necessary) the illuminant's colour and intensity. The camera (Sigma Foveon SD10) was calibrated by measuring its sensor's spectral responses using a set of 31 spectrally narrowband interference filters. This allowed conversion of the final camera-dependent RGB colour space into the Smith and Pokorny (1975) cone activation space by means of a polynomial transformation, optimised for a set of 1269 Munsell chip reflectances. This new method is an improvement over the usual 3 × 3 matrix transformation which is only accurate for spectrally-narrowband colours. The camera-to-LMS transformation can be recalculated to consider other non-human visual systems. The dataset is available to download from our website. |
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CIC |
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no |
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CAT @ cat @ PVV2009 |
Serial |
1193 |
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| Author |
Fadi Dornaika; Jose Manuel Alvarez; Angel Sappa; Antonio Lopez |
| Title |
A New Framework for Stereo Sensor Pose through Road Segmentation and Registration |
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Journal Article |
| Year |
2011 |
Publication |
IEEE Transactions on Intelligent Transportation Systems |
Abbreviated Journal |
TITS |
| Volume |
12 |
Issue |
4 |
Pages |
954-966 |
| Keywords |
road detection |
| Abstract |
This paper proposes a new framework for real-time estimation of the onboard stereo head's position and orientation relative to the road surface, which is required for any advanced driver-assistance application. This framework can be used with all road types: highways, urban, etc. Unlike existing works that rely on feature extraction in either the image domain or 3-D space, we propose a framework that directly estimates the unknown parameters from the stream of stereo pairs' brightness. The proposed approach consists of two stages that are invoked for every stereo frame. The first stage segments the road region in one monocular view. The second stage estimates the camera pose using a featureless registration between the segmented monocular road region and the other view in the stereo pair. This paper has two main contributions. The first contribution combines a road segmentation algorithm with a registration technique to estimate the online stereo camera pose. The second contribution solves the registration using a featureless method, which is carried out using two different optimization techniques: 1) the differential evolution algorithm and 2) the Levenberg-Marquardt (LM) algorithm. We provide experiments and evaluations of performance. The results presented show the validity of our proposed framework. |
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1524-9050 |
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ADAS |
Approved |
no |
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Admin @ si @ DAS2011; ADAS @ adas @ das2011a |
Serial |
1833 |
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| Author |
Javier Vazquez; J. Kevin O'Regan; Maria Vanrell; Graham D. Finlayson |
| Title |
A new spectrally sharpened basis to predict colour naming, unique hues, and hue cancellation |
Type |
Journal Article |
| Year |
2012 |
Publication |
Journal of Vision |
Abbreviated Journal |
VSS |
| Volume |
12 |
Issue |
6 (7) |
Pages |
1-14 |
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| Abstract |
When light is reflected off a surface, there is a linear relation between the three human photoreceptor responses to the incoming light and the three photoreceptor responses to the reflected light. Different colored surfaces have different linear relations. Recently, Philipona and O'Regan (2006) showed that when this relation is singular in a mathematical sense, then the surface is perceived as having a highly nameable color. Furthermore, white light reflected by that surface is perceived as corresponding precisely to one of the four psychophysically measured unique hues. However, Philipona and O'Regan's approach seems unrelated to classical psychophysical models of color constancy. In this paper we make this link. We begin by transforming cone sensors to spectrally sharpened counterparts. In sharp color space, illumination change can be modeled by simple von Kries type scalings of response values within each of the spectrally sharpened response channels. In this space, Philipona and O'Regan's linear relation is captured by a simple Land-type color designator defined by dividing reflected light by incident light. This link between Philipona and O'Regan's theory and Land's notion of color designator gives the model biological plausibility. We then show that Philipona and O'Regan's singular surfaces are surfaces which are very close to activating only one or only two of such newly defined spectrally sharpened sensors, instead of the usual three. Closeness to zero is quantified in a new simplified measure of singularity which is also shown to relate to the chromaticness of colors. As in Philipona and O'Regan's original work, our new theory accounts for a large variety of psychophysical color data. |
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CIC |
Approved |
no |
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Admin @ si @ VOV2012 |
Serial |
1998 |
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| Author |
Oriol Ramos Terrades; Ernest Valveny |
| Title |
A new use of the ridgelets transform for describing linear singularities in images |
Type |
Journal Article |
| Year |
2006 |
Publication |
Pattern Recognition Letters |
Abbreviated Journal |
PRL |
| Volume |
27 |
Issue |
6 |
Pages |
587–596 |
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DAG |
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no |
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DAG @ dag @ RaV2006a |
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635 |
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| Author |
Jon Almazan; Alicia Fornes; Ernest Valveny |
| Title |
A non-rigid appearance model for shape description and recognition |
Type |
Journal Article |
| Year |
2012 |
Publication |
Pattern Recognition |
Abbreviated Journal |
PR |
| Volume |
45 |
Issue |
9 |
Pages |
3105--3113 |
| Keywords |
Shape recognition; Deformable models; Shape modeling; Hand-drawn recognition |
| Abstract |
In this paper we describe a framework to learn a model of shape variability in a set of patterns. The framework is based on the Active Appearance Model (AAM) and permits to combine shape deformations with appearance variability. We have used two modifications of the Blurred Shape Model (BSM) descriptor as basic shape and appearance features to learn the model. These modifications permit to overcome the rigidity of the original BSM, adapting it to the deformations of the shape to be represented. We have applied this framework to representation and classification of handwritten digits and symbols. We show that results of the proposed methodology outperform the original BSM approach. |
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0031-3203 |
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DAG |
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no |
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DAG @ dag @ AFV2012 |
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1982 |
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| Author |
Jaume Garcia; Debora Gil; Luis Badiella; Aura Hernandez-Sabate; Francesc Carreras; Sandra Pujades; Enric Marti |
| Title |
A Normalized Framework for the Design of Feature Spaces Assessing the Left Ventricular Function |
Type |
Journal Article |
| Year |
2010 |
Publication |
IEEE Transactions on Medical Imaging |
Abbreviated Journal |
TMI |
| Volume |
29 |
Issue |
3 |
Pages |
733-745 |
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| Abstract |
A through description of the left ventricle functionality requires combining complementary regional scores. A main limitation is the lack of multiparametric normality models oriented to the assessment of regional wall motion abnormalities (RWMA). This paper covers two main topics involved in RWMA assessment. We propose a general framework allowing the fusion and comparison across subjects of different regional scores. Our framework is used to explore which combination of regional scores (including 2-D motion and strains) is better suited for RWMA detection. Our statistical analysis indicates that for a proper (within interobserver variability) identification of RWMA, models should consider motion and extreme strains. |
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0278-0062 |
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IAM |
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no |
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IAM @ iam @ GGH2010b |
Serial |
1507 |
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