R. K. Agrawal

An improved intuitionistic fuzzy c-means clustering algorithm incorporating local information for brain image segmentation

Original and segmented simulated brain image by different algorithms: (a) axial view of original simulated T1-weighted brain image with INU=0 and 1% noise, (b) skull stripping simulated brain image, (c) manual segmented CSF, GM and WM images, (d) IIFCM algorithm, (e) IFCM algorithm, (f) FLICM algorithm, (g) EnFCM algorithm, (h) FGFCM algorithm, (i) FCM_S1 algorithm, (j) FCM_S2 algorithm, (k) ImFCM algorithm. The segmentation of brain magnetic resonance (MR) images plays an important role in the computer-aided diagnosis and clinical research. However, due to presence of noise and uncertainty on the boundary between different tissues in the brain image, the segmentation of brain image is a challenging task. Many variants of standard fuzzy c-means (FCM) algorithm have been proposed to handle the noise. Intuitionistic fuzzy c-means (IFCM) algorithm, one of the variants of FCM, is found suitable for image segmentation. It incorporates the advantage of intuitionistic fuzzy sets theory. The IFCM successfully handles the uncertainty but it is sensitive to noise as it does not incorporate any local spatial information. In this paper, we have presented a novel approach, named an improved intuitionistic fuzzy c-means (IIFCM), which considers the local spatial information in an intuitionistic fuzzy way. The IIFCM preserves the image details, is insensitive to noise, and is free of requirement of any parameter tuning. The obtained segmentation results on synthetic square image, real and simulated MRI brain image demonstrate the efficacy of the IIFCM algorithm and superior performance in comparison to existing segmentation methods. A nonparametric statistical analysis is also carried out to show the significant performance of the IIFCM algorithm in comparison to other existing segmentation algorithms.

A novel approach to combine features for salient object detection using constrained particle swarm optimization

Despite significant amount of research works, the best available visual attention models still lag far behind human performance in predicting salient object. In this paper, we present a novel approach to detect a salient object which involves two phases. In the first phase, three features such as multi-scale contrast, center-surround histogram and color spatial distribution are obtained as described in Liu et al. model. Constrained Particle Swarm Optimization is used in the second phase to determine an optimal weight vector to combine these features to obtain saliency map to distinguish a salient object from the image background. To achieve this, we defined a simple fitness function which highlights a salient object region with well-defined boundary and effectively suppresses the background regions in an image. The performance is evaluated both qualitatively and quantitatively on a publicly available dataset. Experimental results demonstrate that the proposed model outperforms existing state-of-the-art methods in terms of precision, recall, F -measure and area under curve.

Incremental Bayesian classification for multivariate normal distribution data

Bayesian classifier is an effective and fundamental methodology for solving classification problems. However, it is computationally efficient when all features are considered simultaneously. But sometimes all the features do not contribute significantly to classification. Also the noisy attributes sometimes may decrease the accuracy of classifier. So before classification feature selection is used as a pre-processing step. When the features are added one by one in Bayesian classifier in batch mode in forward selection method huge computation is involved. In this paper, an incremental Bayesian classifier for multivariate normal distribution datasets are proposed. The proposed incremental Bayesian classifier is computationally efficient over batch Bayesian classifier in terms of time. The effectiveness of the proposed incremental Bayesian classifier has been demonstrated through experiments on different datasets. It is found on the basis of experiments that the incremental Bayesian classifier has an equivalent power compared to batch Bayesian classifier in terms classification accuracy. However, the proposed incremental Bayesian classifier has very high speed efficiency in comparison to batch Bayesian classifier.

A novel hybrid approach for salient object detection using local and global saliency in frequency domain

In this paper, we introduce a fast and novel biologically plausible frequency domain approach to detect salient object which incorporates both local and global salient features. The proposed approach involves three phases. In the first phase, locally salient features are obtained as suggested in the research work of Bian and Zhang. Globally salient features are computed in the second phase using fast Walsh-Hadamard transform since it is computationally more efficient and faster than fast Fourier transform. Finally the saliency map is generated in terms of linear weighted combination of local and global saliency maps where the weights are determined using entropy measure. The performance is evaluated both qualitatively and quantitatively on two publicly available datasets and one new dataset derived from a publicly available dataset. Experiments show that the proposed model significantly outperforms other relevant existing state-of-the-art methods in both spatial and frequency domain. The proposed method is also computationally less expensive to detect salient object accurately.

Improved fuzzy entropy clustering algorithm for MRI brain image segmentation

Magnetic resonance imaging (MRI) brain image segmentation is essential at preliminary stage in the neuroscience research and computer‐aided diagnosis. However, presence of noise and intensity inhomogeneity in MRI brain images leads to improper segmentation. The fuzzy entropy clustering (FEC) is often used to deal with noisy data. One major disadvantage of the FEC algorithm is that it does not consider the local spatial information. In this article, we have proposed an improved fuzzy entropy clustering (IFEC) algorithm by introducing a new fuzzy factor, which incorporates both local spatial and gray‐level information. The IFEC algorithm is insensitive to noise, preserves the image detail during clustering, and is free of parameter selection. The efficacy of IFEC algorithm is demonstrated by comparing it quantitatively with the state‐of‐the‐art segmentation approaches in terms of similarity index on publically available real and simulated MRI brain images.

Combining multiple time series models through a robust weighted mechanism

Improvement of time series forecasting accuracy through combining multiple models is an important as well as a dynamic area of research. As a result, various forecasts combination methods have been developed in literature. However, most of them are based on simple linear ensemble strategies and hence ignore the possible relationships between two or more participating models. In this paper, we propose a robust weighted nonlinear ensemble technique which considers the individual forecasts from different models as well as the correlations among them while combining. The proposed ensemble is constructed using three well-known forecasting models and is tested for three real-world time series. A comparison is made among the proposed scheme and three other widely used linear combination methods, in terms of the obtained forecast errors. This comparison shows that our ensemble scheme provides significantly lower forecast errors than each individual model as well as each of the four linear combination methods.

A convex hull approach in conjunction with Gaussian mixture model for salient object detection

The capability of humans in distinguishing salient objects from background is at par excellence. The researchers are yet to develop a model that matches the detection accuracy as well as computation time taken by the humans. In this paper we attempted to improve the detection accuracy without capitalizing much of computation time. The model utilizes the fact that maximal amount of information is present at the corners and edges of an object in the image. Firstly the keypoints are extracted from the image by using multi-scale Harris and multi-scale Gabor functions. Then the image is roughly segmented into two regions: a salient region and a background region, by constructing a convex hull over these keypoints. Finally the pixels of the two regions are considered as samples to be drawn from a multivariate kernel function whose parameters are estimated using expectation maximization algorithm, to yield a saliency map. The performance of the proposed model is evaluated in terms of precision, recall, F-measure, area under curve and computation time using six publicly available image datasets. Experimental results demonstrate that the proposed model outperformed the existing state-of-the-art methods in terms of recall, F-measure and area under curve on all the six datasets, and precision on four datasets. The proposed method also takes comparatively less computation time in comparison to many existing methods.

Combination of Kullback–Leibler divergence and Manhattan distance measures to detect salient objects

Salient object detection is a computer vision technique that filters out redundant visual information and considers potentially relevant parts of our visual field. In this paper, we modify the Liu et al. model for salient object detection, which combines multi-scale contrast, center–surround histogram and color spatial distribution with conditional random fields. A combination of Symmetric Kullback–Leibler divergence and Manhattan distance instead of chi-square measure is employed to determine center–surround histogram difference. The modified Liu et al. model also uses a less computational intensive color spatial distribution map. To check the efficacy of the modified Liu et al. model, the performance is evaluated in terms of precision, recall,

A novel position prior using fusion of rule of thirds and image center for salient object detection

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