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In this paper, we propose a continuous hand gesture recognition method based on trajectory shape information. A key issue in recognizing continuous gestures is that performance of conventional recognition algorithms may be lowered by such factors as, unknown start and end points of a gesture or variations in gesture duration. These issues become particularly difficult for those methods that rely on temporal information. To alleviate the issues of continuous gesture recognition, we propose a framework that simultaneously performs both segmentation and recognition. Each component of the framework applies shape-based information to ensure robust performance for gestures with large temporal variation. A gesture trajectory is divided by a set of key frames by thresholding its tangential angular change. Variable-sized trajectory segments are then generated using the selected key frames. For recognition, these trajectory segments are examined to determine whether the segment belongs to a class among intended gestures or a non-gesture class based on fusion of shape information and temporal features. In order to assess performance, the proposed algorithm was evaluated with a database of digit hand gestures. The experimental results indicate that the proposed algorithm has a high recognition rate while maintaining its performance in the presence of continuous gestures. [ABSTRACT FROM AUTHOR]

We present a method through which domestic service robots can comprehend natural language instructions. For each action type, a variety of natural language expressions can be used, for example, the instruction, ‘Go to the kitchen’ can also be expressed as ‘Move to the kitchen.’ We are of the view that natural language instructions are intuitive and, therefore, constitute one of the most user-friendly robot instruction methods. In this paper, we propose a method that enables robots to comprehend instructions spoken by a human user in his/her natural language. The proposed method combines action-type classification, which is based on a support vector machine, and slot extraction, which is based on conditional random fields, both of which are required in order for a robot to execute an action. Further, by considering the co-occurrence relationship between the action type and the slots along with the speech recognition score, the proposed method can avoid degradation of the robot’s comprehension accuracy in noisy environments, where inaccurate speech recognition can be problematic. We conducted experiments using a Japanese instruction data-set collected using a questionnaire-based survey. Experimental results show that the robot’s comprehension accuracy is higher in a noisy environment using our method than when using a baseline method with only a 1-best speech recognition result. [ABSTRACT FROM AUTHOR]

In this study, the authors investigate how to find correspondences (pixel-level matches) between two video sequences with overlapping views, recorded by different stationary uncalibrated video cameras, without imposing any constrains on, or requiring any a priori knowledge of, the viewing or the illumination conditions under which these videos were obtained. They propose a matching method using a low-level feature, spatiotemporal activity (STA), which effectively combines both the photometric features and the statistic features and makes the proposed method robust to the pose, illumination and geometric effects. They formulate the author's matching problem as a conditional random field model and optimise it by using graph cuts, instead of applying exhaustive pixel-wise matching. A qualitative analysis of the performance improvement compared with the temporal activity-based matching method (TAM) is given by inference from a mathematical model and the quantitative results compared with the TAM and the scale-invariant feature transform (SIFT) are presented with real life examples. The experiments show that their method significantly outperforms the state-of-the-art methods with a higher accuracy and is orders of magnitudes faster than the comparable ones. [ABSTRACT FROM AUTHOR]

Objective: Evaluate the effectiveness and robustness of Anonym, a tool for de-identifying free-text health records based on conditional random fields classifiers informed by linguistic and lexical features, as well as features extracted by pattern matching techniques. De-identification of personal health information in electronic health records is essential for the sharing and secondary usage of clinical data. De-identification tools that adapt to different sources of clinical data are attractive as they would require minimal intervention to guarantee high effectiveness. Methods and materials: The effectiveness and robustness of Anonym are evaluated across multiple datasets, including the widely adopted Integrating Biology and the Bedside (i2b2) dataset, used for evaluation in a de-identification challenge. The datasets used here vary in type of health records, source of data, and their quality, with one of the datasets containing optical character recognition errors. Results: Anonym identifies and removes up to 96.6% of personal health identifiers (recall) with a precision of up to 98.2% on the i2b2 dataset, outperforming the best system proposed in the i2b2 challenge. The effectiveness of Anonym across datasets is found to depend on the amount of information available for training. Conclusion: Findings show that Anonym compares to the best approach from the 2006 i2b2 shared task. It is easy to retrain Anonym with new datasets; if retrained, the system is robust to variations of training size, data type and quality in presence of sufficient training data. [ABSTRACT FROM AUTHOR]

Most existing color constancy algorithms assume uniform illumination. However, in real-world scenes, this is not often the case. Thus, we propose a novel framework for estimating the colors of multiple illuminants and their spatial distribution in the scene. We formulate this problem as an energy minimization task within a conditional random field over a set of local illuminant estimates. In order to quantitatively evaluate the proposed method, we created a novel data set of two-dominant-illuminant images comprised of laboratory, indoor, and outdoor scenes. Unlike prior work, our database includes accurate pixel-wise ground truth illuminant information. The performance of our method is evaluated on multiple data sets. Experimental results show that our framework clearly outperforms single illuminant estimators as well as a recently proposed multi-illuminant estimation approach. [ABSTRACT FROM PUBLISHER]

Highlights: [•] Combine manual and non-manual signals to recognize sign language. [•] Apply a hierarchical CRF to discriminate between signs and fingerspelling. [•] Recognize a facial expression to analyze the specific lexical meaning of signed utterance. [Copyright &y& Elsevier]

Abstract: This paper presents a new general framework for contour tracking based on the synergy of two powerful segmentation tools, namely, spatial temporal conditional random fields (CRFs) and geodesic active contours (GACs). The contours of targets are modeled using a level set representation. The evolution of the level sets toward the target contours is formulated as one of the joint region-based (CRF) and boundary-based (GAC) segmentations under a unified Bayesian framework. A variational inference technique is used to solve this otherwise intractable inference problem, leading to approximate MAP solutions of both the new 3D spatial temporal CRF and the GAC model. The tracking result of the previous frame is used to initialize the curve in the current frame. Typical contour tracking problems are considered and experimental results are given to illustrate the robustness of the method against noise and its accurate performance in moving objects boundary localization. [ABSTRACT FROM AUTHOR]