Patch-based image classification through conditional random field model

In order to improve the performance of Khmer named entity recognition(NER), a NER method based on conditional random field (CRF) model fusing with Khmer entity characteristics constraints is proposed in this paper. First of all, we carried out analyses on the Khmer entity characteristics, summarized the constraint on these entity characteristics and introduced into the CRF; then solved the labeling sequence by integer linear programming integrated entity characteristic constraint and obtained a model of CRF integrated with constraints based on Khmer entity characteristics. Based on a contrastive experiment, CRF model of the constraint has a better performance than traditional CRF model when carrying out the Khmer NER.

Occlusion reasoning is a fundamental problem in computer vision. In this paper, we propose an algorithm to recover the occlusion boundaries and depth ordering of free-standing structures in the scene. Rather than viewing the problem as one of pure image processing, our approach employs cues from an estimated surface layout and applies Gestalt grouping principles using a conditional random field (CRF) model. We propose a hierarchical segmentation process, based on agglomerative merging, that re-estimates boundary strength as the segmentation progresses. Our experiments on the Geometric Context dataset validate our choices for features, our iterative refinement of classifiers, and our CRF model. In experiments on the Berkeley Segmentation Dataset, PASCAL VOC 2008, and LabelMe, we also show that the trained algorithm generalizes to other datasets and can be used as an object boundary predictor with figure/ground labels.

In this paper an automatic method to implicitly model intonation for statistical parametric speech synthesis (SPSS) is presented. The approach is ideally suited to single speaker speech databases as used in text-to-speech (TTS), due to the models being speaker-specific. Fundamental frequency curves are automatically stylized based on the speaker-specific acoustics in the recorded database, requiring no models rooted in linguistic theory, and therefore being well suited to intonation modelling in under-resourced languages. The stylized curves are then coded into abstract pitch labels, which are used as features in the training of the statistical parametric acoustic models. A conditional random field (CRF) model is trained in order to predict the abstract pitch labels from the text for synthesis. The CRF model can be used to predict the abstract pitch labels on the syllable, word and phrase tiers. Objective and subjective results on synthetic voices built from English and isiXhosa speech databases are shown.

The amount of legislative documents produced within the past decade has risen dramatically, making it difficult for law practitioners to consult and update legislation. Named Entity Recognition (NER) systems have the untapped potential to extract information from legal documents, which can improve information retrieval and decision-making processes. We introduce the UlyssesNER-Br, a corpus of Brazilian Legislative Documents for NER with quality baselines. The presented corpus consists of bills and legislative consultations from Brazilian Chamber of Deputies. We implemented Conditional Random Field (CRF) and Hidden Markov Model (HMM) models, and the promising F1-score of 80.8% in the analysis by categories and 81.04% in the analysis by types, was achieved with the CRF model. The entities with the best average F1-score results were “FUNDlei” and “DATA”, and the ones with the worst results were “EVENTO” and “PESSOAgrupoind”. The corpus was also evaluated using a BiLSTM-CRF and Glove architectures provided by the pioneering state-of-the-art paper, achieving F1-score of 76.89% in the analysis by categories and 59.67% in the analysis by types.

The Conditional Random Fields (CRFs) only can deal with the sequence data of Markov property. And it cannot realize the relationship labeling with more fine structure between semantic roles. An approach to semantic role labeling (SRL) based on Chain Conditional Random Fields (CCRFs) Model was proposed. The long-distance dependencies between different state variants were handled effectively via labeling Hierarchical Dependencies and Brother Dependencies of syntactic dependency tree. Moreover, some new combinative features and prepositional phrase also were added though taking advantages of any features can be added in CRFs model. The experiments were implemented on CoNLL 2008 Shared Task. The results indicate the proposed method can improve precision and recall rate of the system.

Contour detection is a fundamental problem in computer vision. However, there is still a considerable disparity between detection results and actual contours. To detect object-level contours on the basis of comprehensive analysis of potential edges, we present a deep-learning-based approach with a conditional random fields (CRF) model. We obtain the initial edgemap with a VGGNet-based model, and establish a contour correlation graph (CCG) to describe the potential edges and their relationships. Then a CRF model is adopted to fulfill the optimization on the basis of the analysis of object-level contour characteristics and to predict the validity of candidate contours. The experiment results on various datasets demonstrate that the proposed method outperforms the existing methods by a noticeable margin.

In this paper we present a novel conditional random field (CRF) model based on Laplacian mixtures for image labeling. Nature images posses many spatial regularities that can be efficiently modeled by probabilistic graphical models such as CRF. Usually hundreds of features and several types of feature functions are used together which increases computational complexity and makes the training difficult to converge. We propose a new Laplacian mixture CRF model, which simplifies the training and inference process without losing labeling accuracy. The belief propagation inference and stochastic gradient descent training are formulated accordingly for the new model. The experimental results demonstrate that the new approach achieves better classification accuracy than the baseline CRF and comparable results with the state-of-the-art complex models.

Many downscaling techniques have been developed in the past few years for projection of station‐scale hydrological variables from large‐scale atmospheric variables simulated by general circulation models (GCMs) to assess the hydrological impacts of climate change. This article compares the performances of three downscaling methods, viz. conditional random field (CRF), K‐nearest neighbour (KNN) and support vector machine (SVM) methods in downscaling precipitation in the Punjab region of India, belonging to the monsoon regime. The CRF model is a recently developed method for downscaling hydrological variables in a probabilistic framework, while the SVM model is a popular machine learning tool useful in terms of its ability to generalize and capture nonlinear relationships between predictors and predictand. The KNN model is an analogue‐type method that queries days similar to a given feature vector from the training data and classifies future days by random sampling from a weighted set of K closest training examples. The models are applied for downscaling monsoon (June to September) daily precipitation at six locations in Punjab. Model performances with respect to reproduction of various statistics such as dry and wet spell length distributions, daily rainfall distribution, and intersite correlations are examined. It is found that the CRF and KNN models perform slightly better than the SVM model in reproducing most daily rainfall statistics. These models are then used to project future precipitation at the six locations. Output from the Canadian global climate model (CGCM3) GCM for three scenarios, viz. A1B, A2, and B1 is used for projection of future precipitation. The projections show a change in probability density functions of daily rainfall amount and changes in the wet and dry spell distributions of daily precipitation. Copyright © 2011 John Wiley & Sons, Ltd.

The paper presented a novel discriminative model for efficient and effective recognition and simultaneous semantic segmentation of objects in images. The images are first segmented to give 'super-pixels'. Then the super-pixels are merged together and semantically labeled using a Condition Random Field (CRF) model. The use of a conditional random field allows us to incorporate different cues in a single unified model. The test on the standard dataset shows that compared with existing systems, the proposed system produces a detailed segmentation of a test image into coherent regions, with a semantic label associated with each region in the image.

Interactive image segmentation has gained much popularity since it can enhance the segmentation performance with human interactions. In this paper, we propose a novel framework that can effectively estimate the binary labels based on Conditional Random Field (CRF) models combining region-level information with pixels-level information. The user scribbles are treated as soft constraints. We use pixel-layer with local CRF and region-layer with fully connected CRF to model the graph. Then we combine the pixel information and region information together to calculate the pixels' likelihood term. In contrast to using relations between the pixel-layer and the region-layer during the probability computation, we calculate the probabilities of pixels and regions separately to reduce computational complexity. After the likelihood computation, a graph cut based model is used to refine the pixel-level label predictions of the image in order to avoid label inconsistency in regions and capture the boundary details. Due to the less relationship between layers and utilizing the refinement, the proposed model can provide high accuracy and user inputs insensitive results. Our experiments show that the proposed approach can efficiently and accurately segment the images compared with other state of art methods with only a few scribbles. Graph cut based fine tuning improves our segmentation accuracy and our method needs less computational cost than traditional multi-layer-based methods.

Variational conditional random fields for online speaker detection and tracking

In this paper, we propose a synthetic aperture radar (SAR) image change detection algorithm based on SAR image nonstationary analysis and conditional random field (CRF) model. This algorithm segments the SAR images into two nonstationary regions with the Triplet Markov Field (TMF) model which incorporates a U field to describe the images' nonstationary nature. The combined posterior probability of the CRF model consists of two parts: the unary potential and the pairwise potential. The unary potential is modeled by support vector machine (SVM) using the texture features extracted from the two-temporal SAR images, and the pairwise potential is constructed by the multilevel logistical model to capture the spatial interactions of the log-ratio image. Both the unary and pairwise potentials are improved with the introduction of the U field. The parameters of the pairwise potential are estimated by the iterative conditional estimation (ICE) algorithm. The iterative conditional model (ICM) algorithm is utilized for updating the combined posterior probability, and the final change detection results are obtained when it converges. Finally, experimental results on four two-temporal SAR images validate the effectiveness of the proposed image change detection algorithm.

The fast move to digital for HR tasks has led to the creation of a lot of unstructured documents, especially offer letters, which provide important information about employees. Using usual approaches, this has not been processed well for extracting information. This study presents a comprehensive system for the automatic extraction of information from offer letters utilizing optical character recognition (OCR) and named entity recognition. A comparison investigation has been conducted about the performance of the conventional Conditional Random Field (CRF) model and the advanced Bidirectional Encoder Representations from Transformers (BERT) model. This paper presents a system for generating synthetic data to address the challenges of data scarcity and privacy. This framework may create fake data for the process of getting information from offer letters, such as alternative layouts, semantic content, and noise. This paper evaluated the efficacy of the models on a demanding dataset of 500 documents. The findings indicate that, while the traditional Conditional Random Field model yielded satisfactory outcomes, the advanced Bidirectional Encoder Representations from Transformers model produced significantly superior results in comparison to the conventional model. This experimental evaluation also proves the efficiency of the proposed system in extracting key entities such as candidate name, designation, salary, and date of joining accurately from the scanned offer letters. The comparative analysis proves that, although the proposed system using the CRF model works accurately in structured data, the BERT model has a better capacity for understanding the contextual relationship within the document text. Thus, the proposed transformer model proves to be effective in dealing with the variability in the document layouts, linguistic expressions, and document conditions.

To reduce the computation cost of a combined probabilistic graphical model and a deep neural network in semantic segmentation, the local region condition random field (LRCRF) model is investigated which selectively applies the condition random field (CRF) to the most active region in the image. The full convolutional network structure is optimized with the ResNet-18 structure and dilated convolution to expand the receptive field. The tracking networks are also improved based on SiameseFC by considering the frame relations in consecutive-frame traffic scene maps. Moreover, the segmentation results of the greyscale input data sets are more stable and effective than using the RGB images for deep neural network feature extraction. The experimental results show that the proposed method takes advantage of the image features directly and achieves good real-time performance and high segmentation accuracy.

BackgroundDe Bruijn graphs are key data structures for the analysis of next-generation sequencing data. They efficiently represent the overlap between reads and hence, also the underlying genome sequence. However, sequencing errors and repeated subsequences render the identification of the true underlying sequence difficult. A key step in this process is the inference of the multiplicities of nodes and arcs in the graph. These multiplicities correspond to the number of times each k-mer (resp. k+1-mer) implied by a node (resp. arc) is present in the genomic sequence. Determining multiplicities thus reveals the repeat structure and presence of sequencing errors. Multiplicities of nodes/arcs in the de Bruijn graph are reflected in their coverage, however, coverage variability and coverage biases render their determination ambiguous. Current methods to determine node/arc multiplicities base their decisions solely on the information in nodes and arcs individually, under-utilising the information present in the sequencing data.ResultsTo improve the accuracy with which node and arc multiplicities in a de Bruijn graph are inferred, we developed a conditional random field (CRF) model to efficiently combine the coverage information within each node/arc individually with the information of surrounding nodes and arcs. Multiplicities are thus collectively assigned in a more consistent manner.ConclusionsWe demonstrate that the CRF model yields significant improvements in accuracy and a more robust expectation-maximisation parameter estimation. True k-mers can be distinguished from erroneous k-mers with a higher F1 score than existing methods. A C++11 implementation is available at https://github.com/biointec/detoxunder the GNU AGPL v3.0 license.