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Oriol Pujol, Petia Radeva, Jordi Vitria, & J. Mauri. (2004). Adaboost to Classify Plaque Appearance in IVUS Images.
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Marc Masana, Joost Van de Weijer, & Andrew Bagdanov. (2016). On-the-fly Network pruning for object detection. In International conference on learning representations.
Abstract: Object detection with deep neural networks is often performed by passing a few
thousand candidate bounding boxes through a deep neural network for each image.
These bounding boxes are highly correlated since they originate from the same
image. In this paper we investigate how to exploit feature occurrence at the image scale to prune the neural network which is subsequently applied to all bounding boxes. We show that removing units which have near-zero activation in the image allows us to significantly reduce the number of parameters in the network. Results on the PASCAL 2007 Object Detection Challenge demonstrate that up to 40% of units in some fully-connected layers can be entirely eliminated with little change in the detection result.
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David Guillamet, B. Shiele, & Jordi Vitria. (2002). Analyzing Non-negative Matrix Factorization for Image Classification..
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David Guillamet, & Jordi Vitria. (2002). Determining a Suitable Metric when using Non-negative Matrix Factorization..
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Ernest Valveny, & B. Lamiroy. (2002). Automatic Generation of Browsable Technical Documents..
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Cristhian A. Aguilera-Carrasco, Angel Sappa, & Ricardo Toledo. (2015). LGHD: a Feature Descriptor for Matching Across Non-Linear Intensity Variations. In 22th IEEE International Conference on Image Processing (pp. 178–181).
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Carles Sanchez, Debora Gil, Jorge Bernal, F. Javier Sanchez, Marta Diez-Ferrer, & Antoni Rosell. (2016). Navigation Path Retrieval from Videobronchoscopy using Bronchial Branches. In 19th International Conference on Medical Image Computing and Computer Assisted Intervention Workshops (Vol. 9401, pp. 62–70). LNCS.
Abstract: Bronchoscopy biopsy can be used to diagnose lung cancer without risking complications of other interventions like transthoracic needle aspiration. During bronchoscopy, the clinician has to navigate through the bronchial tree to the target lesion. A main drawback is the difficulty to check whether the exploration is following the correct path. The usual guidance using fluoroscopy implies repeated radiation of the clinician, while alternative systems (like electromagnetic navigation) require specific equipment that increases intervention costs. We propose to compute the navigated path using anatomical landmarks extracted from the sole analysis of videobronchoscopy images. Such landmarks allow matching the current exploration to the path previously planned on a CT to indicate clinician whether the planning is being correctly followed or not. We present a feasibility study of our landmark based CT-video matching using bronchoscopic videos simulated on a virtual bronchoscopy interactive interface.
Keywords: Bronchoscopy navigation; Lumen center; Brochial branches; Navigation path; Videobronchoscopy
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Debora Gil, Oriol Ramos Terrades, Elisa Minchole, Carles Sanchez, Noelia Cubero de Frutos, Marta Diez-Ferrer, et al. (2017). Classification of Confocal Endomicroscopy Patterns for Diagnosis of Lung Cancer. In 6th Workshop on Clinical Image-based Procedures: Translational Research in Medical Imaging (Vol. 10550, pp. 151–159). LNCS.
Abstract: Confocal Laser Endomicroscopy (CLE) is an emerging imaging technique that allows the in-vivo acquisition of cell patterns of potentially malignant lesions. Such patterns could discriminate between inflammatory and neoplastic lesions and, thus, serve as a first in-vivo biopsy to discard cases that do not actually require a cell biopsy.
The goal of this work is to explore whether CLE images obtained during videobronchoscopy contain enough visual information to discriminate between benign and malign peripheral lesions for lung cancer diagnosis. To do so, we have performed a pilot comparative study with 12 patients (6 adenocarcinoma and 6 benign-inflammatory) using 2 different methods for CLE pattern analysis: visual analysis by 3 experts and a novel methodology that uses graph methods to find patterns in pre-trained feature spaces. Our preliminary results indicate that although visual analysis can only achieve a 60.2% of accuracy, the accuracy of the proposed unsupervised image pattern classification raises to 84.6%.
We conclude that CLE images visual information allow in-vivo detection of neoplastic lesions and graph structural analysis applied to deep-learning feature spaces can achieve competitive results.
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Simone Balocco, Francesco Ciompi, Juan Rigla, Xavier Carrillo, Josefina Mauri, & Petia Radeva. (2017). Intra-Coronary Stent localization In Intravascular Ultrasound Sequences, A Preliminary Study. In International workshop on Computing and Visualization for Intravascular Imaging and Computer Assisted Stenting (CVII-STENT). LNCS.
Abstract: An intraluminal coronary stent is a metal scaold deployed in a stenotic artery during Percutaneous Coronary Intervention (PCI).
Intravascular Ultrasound (IVUS) is a catheter-based imaging technique generally used for assessing the correct placement of the stent. All the approaches proposed so far for the stent analysis only focused on the struts detection, while this paper proposes a novel approach to detect the boundaries and the position of the stent along the pullback.
The pipeline of the method requires the identication of the stable frames
of the sequence and the reliable detection of stent struts. Using this data,
a measure of likelihood for a frame to contain a stent is computed. Then,
a robust binary representation of the presence of the stent in the pullback
is obtained applying an iterative and multi-scale approximation of the signal to symbols using the SAX algorithm. Results obtained comparing the automatic results versus the manual annotation of two observers on 80 IVUS in-vivo sequences shows that the method approaches the inter-observer variability scores.
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Quentin Angermann, Jorge Bernal, Cristina Sanchez Montes, Gloria Fernandez Esparrach, Xavier Gray, Olivier Romain, et al. (2017). Towards Real-Time Polyp Detection in Colonoscopy Videos: Adapting Still Frame-Based Methodologies for Video Sequences Analysis. In 4th International Workshop on Computer Assisted and Robotic Endoscopy (pp. 29–41).
Abstract: Colorectal cancer is the second cause of cancer death in United States: precursor lesions (polyps) detection is key for patient survival. Though colonoscopy is the gold standard screening tool, some polyps are still missed. Several computational systems have been proposed but none of them are used in the clinical room mainly due to computational constraints. Besides, most of them are built over still frame databases, decreasing their performance on video analysis due to the lack of output stability and not coping with associated variability on image quality and polyp appearance. We propose a strategy to adapt these methods to video analysis by adding a spatio-temporal stability module and studying a combination of features to capture polyp appearance variability. We validate our strategy, incorporated on a real-time detection method, on a public video database. Resulting method detects all
polyps under real time constraints, increasing its performance due to our
adaptation strategy.
Keywords: Polyp detection; colonoscopy; real time; spatio temporal coherence
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Eduardo Tusa, Arash Akbarinia, Raquel Gil Rodriguez, & Corina Barbalata. (2015). Real-Time Face Detection and Tracking Utilising OpenMP and ROS. In 3rd Asia-Pacific Conference on Computer Aided System Engineering (pp. 179–184).
Abstract: The first requisite of a robot to succeed in social interactions is accurate human localisation, i.e. subject detection and tracking. Later, it is estimated whether an interaction partner seeks attention, for example by interpreting the position and orientation of the body. In computer vision, these cues usually are obtained in colour images, whose qualities are degraded in ill illuminated social scenes. In these scenarios depth sensors offer a richer representation. Therefore, it is important to combine colour and depth information. The
second aspect that plays a fundamental role in the acceptance of social robots is their real-time-ability. Processing colour and depth images is computationally demanding. To overcome this we propose a parallelisation strategy of face detection and tracking based on two different architectures: message passing and shared memory. Our results demonstrate high accuracy in
low computational time, processing nine times more number of frames in a parallel implementation. This provides a real-time social robot interaction.
Keywords: RGB-D; Kinect; Human Detection and Tracking; ROS; OpenMP
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Carme Julia, Angel Sappa, Felipe Lumbreras, Joan Serrat, & Antonio Lopez. (2006). Factorization with Missing and Noisy Data. In 6th International Conference on Computational Science (Vol. LNCS 3991, 555–562).
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Angel Sappa, & Fadi Dornaika. (2006). An Edge-Based Approach to Motion Detection. In 6th International Conference on Computational Science (ICCS´06), LNCS 3991:563–570.
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Sergio Escalera, Oriol Pujol, & Petia Radeva. (2009). Recoding Error-Correcting Output Codes. In 8th International Workshop of Multiple Classifier Systems (Vol. 5519, 11–21). Springer Berlin Heidelberg.
Abstract: One of the most widely applied techniques to deal with multi- class categorization problems is the pairwise voting procedure. Recently, this classical approach has been embedded in the Error-Correcting Output Codes framework (ECOC). This framework is based on a coding step, where a set of binary problems are learnt and coded in a matrix, and a decoding step, where a new sample is tested and classified according to a comparison with the positions of the coded matrix. In this paper, we present a novel approach to redefine without retraining, in a problem-dependent way, the one-versus-one coding matrix so that the new coded information increases the generalization capability of the system. Moreover, the final classification can be tuned with the inclusion of a weighting matrix in the decoding step. The approach has been validated over several UCI Machine Learning repository data sets and two real multi-class problems: traffic sign and face categorization. The results show that performance improvements are obtained when comparing the new approach to one of the best ECOC designs (one-versus-one). Furthermore, the novel methodology obtains at least the same performance than the one-versus-one ECOC design.
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Oriol Pujol, Eloi Puertas, & Carlo Gatta. (2009). Multi-scale Stacked Sequential Learning. In 8th International Workshop of Multiple Classifier Systems (Vol. 5519, 262–271). Springer Berlin Heidelberg.
Abstract: One of the most widely used assumptions in supervised learning is that data is independent and identically distributed. This assumption does not hold true in many real cases. Sequential learning is the discipline of machine learning that deals with dependent data such that neighboring examples exhibit some kind of relationship. In the literature, there are different approaches that try to capture and exploit this correlation, by means of different methodologies. In this paper we focus on meta-learning strategies and, in particular, the stacked sequential learning approach. The main contribution of this work is two-fold: first, we generalize the stacked sequential learning. This generalization reflects the key role of neighboring interactions modeling. Second, we propose an effective and efficient way of capturing and exploiting sequential correlations that takes into account long-range interactions by means of a multi-scale pyramidal decomposition of the predicted labels. Additionally, this new method subsumes the standard stacked sequential learning approach. We tested the proposed method on two different classification tasks: text lines classification in a FAQ data set and image classification. Results on these tasks clearly show that our approach outperforms the standard stacked sequential learning. Moreover, we show that the proposed method allows to control the trade-off between the detail and the desired range of the interactions.
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