Comparison and fusion of multiresolution features for texture classification

Our main goal in this paper is to set the foundations of a general continuous-domain framework for designing steerable, reversible signal transformations (a.k.a. frames) in multiple dimensions ( d >or= 2). To that end, we introduce a self-reversible, Nth-order extension of the Riesz transform. We prove that this generalized transform has the following remarkable properties: shift-invariance, scale-invariance, inner-product preservation, and steerability. The pleasing consequence is that the transform maps any primary wavelet frame (or basis) of [Formula: see text] into another "steerable" wavelet frame, while preserving the frame bounds. The concept provides a functional counterpart to Simoncelli's steerable pyramid whose construction was primarily based on filterbank design. The proposed mechanism allows for the specification of wavelets with any order of steerability in any number of dimensions; it also yields a perfect reconstruction filterbank algorithm. We illustrate the method with the design of a novel family of multidimensional Riesz-Laplace wavelets that essentially behave like the N th-order partial derivatives of an isotropic Gaussian kernel.

Multiresolution histograms have been recently proposed as robust and efficient features for texture classification. In this paper, we evaluate the performance of multiresolution histograms for texture classification using support vector machines (SVMs). We observe that the dimensionality of multiresolution histograms can be greatly reduced with a Laplacian pyramidal decomposition. With an appropriate kernel, we show that SVMs significantly improve the performance of multiresolution histograms compared to the previously used nearest-neighbor (NN) classifiers on a texture classification problem involving Brodatz textures. Experimental results indicate that multiresolution histograms in conjunction with SVMs are also robust to noise.

In this paper we proposed a new method for texture classification of ultrasonic liver images based on Gabor wavelet. It is well known that Gabor wavelets attain maximum joint space-frequency resolution which is highly significant in the process of texture extraction in which the conflicting objectives of accuracy in texture representation and texture spatial localization are both important. This fact has been explored in our results as it shows that the classification rate obtained by Gabor wavelet is higher that those obtained using dyadic wavelets. The feature vector consists of 10 elements at each scale from Gabor wavelets which is relatively small compared to other methods. This has a significant impact on the speed of retrieval process. The proposed algorithm applied to discriminate ultrasonic liver images into three disease states that are normal liver, liver hepatitis and cirrhosis. In our experiment 45 liver sample images from each three disease states which already proven by needle biopsy were used. We achieved the sensitivity 85% in the distinction between normal and hepatitis liver images and 86% in the distinction between normal and cirrhosis liver images. Based on our experiments, the Gabor wavelet is more appropriate than dyadic wavelets for texture classification as it leads to higher classification accuracy.

In the present paper, a set of robust texture features based on morphological residues of opening or closing by reconstruction is introduced. This set of features is proven much more robust to noise than those based on traditional morphological residues. The robustness to noise of this set of features is investigated in detail. An algorithm is constructed to select the most discriminating feature subset. In texture classification experiments, it is found that this feature subset bears high robustness to various noises even when the noise levels are quite high.

Investigation of acoustic and visual features for pig cough classification

Malaria being prevalent disease in urban areas, demands its accurate and fast diagnosis. Due to malaria infection in human being, the erythrocyte features got distorted. To diagnose these, various techniques have been developed, i.e., machine learning-based system, rapid diagnostic test, quantitative buffy coat, etc. In machine learning, the system performance depends on the feature set and classifier model. In this paper, the analysis of the importance of the feature set on malaria-infected erythrocyte classification has been performed. Further, a classifier model based on ANN-GA has been developed to classify the erythrocyte. The process consists of illumination correction, erythrocyte segmentation, feature extraction with or without feature selection techniques, and classification. Erythrocytes segmentation is done using image binarization with marker-controlled watershed segmentation. The six feature sets (morphological feature, texture and intensity feature) have been evaluated using various classifiers such as support vector machine (SVM), k-nearest neighbor (k-NN), and Naive Bayes to choose the better feature set. From the experimental results, it has been observed that the feature set \(\textit{f}_6\) (combination of morphological, texture and intensity feature ranked with ANOVA) outperforms other feature sets. Further, erythrocyte classification has been performed using ANN-GA with \(\textit{f}_6\) feature set. It may also conclude that the various features such as morphological feature, texture and intensity feature are equally important to detect the malaria-infected erythrocyte.

The analysis of digital pathology images, catalyzes research and automate diagnosis for improving clinical care. Regardless of the advances in high-resolution and speedy scanning devices, the clinical analysis of Whole Slide Image (WSI) remains mainly as the work of an image analyst. The complications when working on these images are primarily, its enormous image size, as well as the heterogeneous nature of tissue regions. These reasons may lead to inefficient computer analysis. We propose a comprehensive algorithm to analyse, these large images by using small tile image analysis. The small tile images can be learnt individually in detail, rather than processing the whole high resolution WSI. The analysis of these small tile images helps us configure, the localised pathology image characteristics. The work flow involves extracting Perceptual Features (PF), Fourier Local Binary Patterns (FLBP), Histogram, Gabor and Gray Level Co-occurrence Matrix (GLCM) features from the tiled WSI. Then, the multidimensional feature set is provided to the classifiers like K-Nearest Neighbour (KNN), Support Vector Machine (SVM), Naive Bayes (NB) and Logistic Regression (LR) for performance analysis. We evaluated our predictive models by automatically classifying image datasets (186 and 124) of brain tumour cases, using 10 fold cross validation. The model classified the images into Low Grade Glioma (LGG) and Glioblastoma Multiforme (GBM). It gives the highest accuracy of 93.5% for a feature combination of PF+FLBP+GLCM+GABOR with linear Support Vector Machine (linSVM) and Area under the Curve (AUC) of 0.9741 for the 186 image dataset. Also linSVM gives an accuracy of 96.8% with various feature combinations for the 124 image dataset. We did an exhaustive study on the performance of various sets of texture descriptors and classification models. This resulted in finding an optimised classification approach with a combined feature set that outperformed the original feature set classification. The proposed work is unique because it combines a wide range of feature extracting methods and an exhaustive list of classifiers showcasing the best method. The idea that, rather than selecting a region of interest from WSI for grade designation, all the regions in a slide are considered. This enables the involvement of each tile in making the final diagnostic decision, considering the heterogeneous nature of WSI. Our work can be extended for different tumour subtypes. Also, the experiment can be scaled with different sample sizes and finally the method works without a pathologist input.

In this paper we explore automatic genre labelling of motion picture previews using audio-visual features present in movie trailers and the focus is on fusion techniques (early fusion and late fusion) and the resultant improvement on classification accuracy. This paper proposes a novel combination of deep learned features (from a pretrained VGG-16 model) obtained using a state-of-the-art shot detector and hand-crafted audio features. This combination of features and an associated comparison of early and late fusion with these features has not been attempted in the literature before. Furthermore, two popular fusion techniques and three distinct classification algorithms are investigated to determine the optimal fusion technique and classifier combination. The study uses a subset of the LMTD-9 movie trailer dataset with selected genres (action, comedy, drama and horror). The best performing low-level audio features are comprised of timbre features extracted using the MIRtoolbox followed by standalone mel-frequency cepstral coefficients. The best performing high-level audio feature is tonality. Audio features are augmented by visual features extracted using a pre-trained convolutional neural network (VGG-16). Feature fusion (early and late fusion) methods are investigated together with classification methods such as extreme gradient boosting, support vector machine and a neural network. Evaluation metrics such as precision, recall, confusion matrices and F1 score are used to measure classification accuracy. Early fusion methods outperform late fusion methods with a classification performance gain of approximately 10% for a four class classification problem. The best classification performance for early fusion obtained with a support vector machine is (73.12% accuracy), followed by the extreme gradient boosting classifier (69.37% accuracy) and neural network classifier (67.50% accuracy), whereas chance is 25%. It is shown that superior classification performance can be achieved by employing early feature fusion of low-level audio descriptors, high-level audio descriptors and high-level visual feature descriptors together with suitable classifiers.

Gabor Wavelet Selection and SVM Classification for Object Recognition

In this paper, a liver diseases diagnosis based on Gabor wavelets and support vector machine (SVM) classifier is proposed. The diagnosis scheme includes two steps: features extraction and classification. The features derived from Gabor wavelets are obtained from the regions of interest (ROIs) among the normal and abnormal CT images. In the classification step, the SVM classifier is used to discriminate the fiver diseases. Finally the receiver operating characteristic (ROC) curve is employed to evaluate the performance of the diagnosis system. Three kinds of fiver diseases are identified including cyst, hepatoma and cavernous hemangioma. The effectiveness of the proposed method is demonstrated through experimental results on CT images including 76 fiver cysts, 30 hepatomas, and 40 cavernous hemangiomas. From the results we can observe that the discrimination rate of cyst is higher than other diseases, and the classification accuracy decreases slightly between cavernous hemangiomas and hepatomas. However, a normal region can be discriminated from all of these diseases at most entirety.

In this work, we are attempting emotion classification in view of synthesizing story speech. We are proposing emotion-specific text features (ESF) for classifying sentences from children stories into five different emotion categories: happy, sad, anger, fear and neutral. ESF is a five dimensional feature vector, where each dimension corresponds to weight of the sentence according to each emotion class. The dataset consists of 780 Hindi emotional sentences collected from children stories belonging to three genres: fable, folk-tale and legend. Part-of-speech (POS) and proposed ESF are used as features for emotion classification. Emotion classification performance is analysed using various combinations of features with three classifiers: Naive Bayes (NB), k-nearest neighbour (KNN) and support vector machine (SVM). The effectiveness of classifiers is analysed using precision, recall, F-measure and accuracy. The classification performance of 67.9% and 67.2% is achieved using POS and ESF respectively. The fusion of both features resulted an accuracy of 71.1%. Further, the importance of story genre information in emotion classification was observed from the experiments conducted on classifying emotions within story genre. An accuracy of 73.7% was observed after adding story genre information to the fusion of POS and ESF. SVM models outperformed other models in terms of classification accuracy.

In the field of computer vision and image processing CBIR (Content based image retrieval) system become an active research area. The CBIR technique involves feature extraction based on image features (like color, shape and texture) and defining rules for comparing image. A classifier is also used by authors for image classification. For this purpose an image database taken from James Z. Wang research group website is used by many authors. Due to enormous increase in the size of database traditional methods of image retrieval by using keywords does not provide accurate result. Thus the concept of CBIR system is emerged. In last couple of years many method of feature extraction is developed but since now researcher are not able to develop a system which has gained high accuracy of human visual perception in distinguishing pictures. Therefore earlier researchers have concentrated to increase the retrieval accuracy of CBIR system by using different combination of features. The objective of this paper is to present review on a CBIR technique which combined four kinds of features set including every kind of feature for developing feature vector. Color based features (histogram), statistical features (mean, median and standard deviation), spatial features (Gabor feature and wavelet features) and texture features (GLCM) is used for forming feature vector. A SVM classifier is used with CBIR system to increase retrieval accuracy. SVM (support vector machine) is a machine learning classifier which provides good classification accuracy. Keywords: CBIR, SVM, NN, GLCM, HSV Color space, Euclidean distance matrix.

We propose a new feature vector consisting of mel-frequency discrete wavelet coefficients (MFDWC). The MFDWC are obtained by applying the discrete wavelet transform (DWT) to the mel-scaled log filterbank energies of a speech frame. The purpose of using the DWT is to benefit from its localization property in the time and frequency domains. MFDWC are similar to subband-based (SUB) features and multi-resolution (MULT) features in that both attempt to achieve good time and frequency localization. However, MFDWC have better time/frequency localization than SUB features and MULT features. We evaluated the performance of new features for clean speech and noisy speech and compared the performance of MFDWC with mel-frequency cepstral coefficients (MFCC), SUB features and MULT features. Experimental results on a phoneme recognition task showed that a MFDWC-based recognizer gave better results than recognizers based on MFCC, SUB features, and MULT features for white Gaussian noise, band-limited white Gaussian noise and clean speech cases.

Recently, digital content has become a significant and inevitable asset of or any enterprise and the need for visual content management is on the rise as well. Content-based image retrieval has attracted voluminous research in the last decade paving way for development of numerous techniques and systems besides creating interest on fields that support these systems. CBIR indexes the images based on the features obtained from visual content so as to facilitate speedy retrieval. In this thesis work, we present a steerable pyramid based image retrieval system that uses color, contours and texture as visual features to describe the content of an image region. We have initially used steerable pyramid to extract texture features from query image and database images and store them in feature vectors. Second, to speed up retrieval and similarity computation, the database images are classified and the extracted regions are clustered according to their feature vectors using median vector algorithm. This process is performed before query matching takes place. Therefore to answer a query our system does not need to search the entire database images; instead just a number of candidate images are required to be searched for image similarity. Our proposed system has the advantage of increasing the retrieval accuracy and decreasing the retrieval time. The experimental evaluation of the system is based on a satellite and medical image database. From the experimental results, it is evident that our system performs significantly better and faster compared with other existing systems. In our analysis, we provide a comparison between retrieval results based on features extracted from the whole image using steerable pyramid with median vector and features extracted from same image without median vector. The results demonstrate that each type of feature is effective for a particular type of images according to its semantic contents, and using a combination of them giving better retrieval results for almost all different classes of images in the dataset. Â

BackgroundExogenous short interfering RNAs (siRNAs) induce a gene knockdown effect in cells by interacting with naturally occurring RNA processing machinery. However not all siRNAs induce this effect equally. Several heterogeneous kinds of machine learning techniques and feature sets have been applied to modeling siRNAs and their abilities to induce knockdown. There is some growing agreement to which techniques produce maximally predictive models and yet there is little consensus for methods to compare among predictive models. Also, there are few comparative studies that address what the effect of choosing learning technique, feature set or cross validation approach has on finding and discriminating among predictive models.Principal FindingsThree learning techniques were used to develop predictive models for effective siRNA sequences including Artificial Neural Networks (ANNs), General Linear Models (GLMs) and Support Vector Machines (SVMs). Five feature mapping methods were also used to generate models of siRNA activities. The 2 factors of learning technique and feature mapping were evaluated by complete 3×5 factorial ANOVA. Overall, both learning techniques and feature mapping contributed significantly to the observed variance in predictive models, but to differing degrees for precision and accuracy as well as across different kinds and levels of model cross-validation.ConclusionsThe methods presented here provide a robust statistical framework to compare among models developed under distinct learning techniques and feature sets for siRNAs. Further comparisons among current or future modeling approaches should apply these or other suitable statistically equivalent methods to critically evaluate the performance of proposed models. ANN and GLM techniques tend to be more sensitive to the inclusion of noisy features, but the SVM technique is more robust under large numbers of features for measures of model precision and accuracy. Features found to result in maximally predictive models are not consistent across learning techniques, suggesting care should be taken in the interpretation of feature relevance. In the models developed here, there are statistically differentiable combinations of learning techniques and feature mapping methods where the SVM technique under a specific combination of features significantly outperforms all the best combinations of features within the ANN and GLM techniques.