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Fracture of the bone is a very serious medical condition. In clinical practice, a tired radiologist has been found to miss fracture cases after looking through many images containing healthy bones. Computer detection of fractures can assist the doctors by flagging suspicious cases for closer examinations and thus improve the timeliness and accuracy of their diagnosis. This paper presents a new divide-and-conquer approach for fracture detection by partitioning the problem into smaller sub-problems in SVM's kernel space, and training an SVM to specialize in solving each sub-problem. As the sub-problems are easier to solve than the whole problem, a hierarchy of SVMs performs better than an individual SVM that solves the whole problem. Compared to existing methods, this approach enhances the accuracy and reliability of SVMs. [ABSTRACT FROM AUTHOR]

The Nearest Neighbor (NN) rule is one of the simplest and most effective pattern classification algorithms. In basic NN rule, all the instances in the training set are considered the same to find the NN of an input test pattern. In the proposed approach in this article, a local weight is assigned to each training instance. The weights are then used while calculating the adaptive distance metric to find the NN of a query pattern. To determine the weight of each training pattern, we propose a learning algorithm that attempts to minimize the number of misclassified patterns on the training data. To evaluate the performance of the proposed method, a number of UCI-ML data sets were used. The results show that the proposed method improves the generalization accuracy of the basic NN classifier. It is also shown that the proposed algorithm can be considered as an effective instance reduction technique for the NN classifier. [ABSTRACT FROM AUTHOR]

The use of traditional moment invariants is limited to a certain set of simple geometric transforms, such as rotation, scaling and affine transform. This paper presents a novel concept of so-called implicit moment invariants, which enable us to recognize objects under a broader set of geometric deformations. [ABSTRACT FROM AUTHOR]

This paper explores the use of tree-based data structures in shape analysis. We consider a structure which combines several properties of traditional tree models and obtain an efficiently compressed yet faithful representation of shapes. Constructed in a top-down fashion, the resulting trees are unbalanced but resolution adaptive. While the interior of a shape is represented by just a few nodes, the structure automatically accounts for more details at wiggly parts of a shape's boundary. Since its construction only involves simple operations, the structure provides an easy access to salient features such as concave cusps or maxima of curvature. Moreover, tree serialization leads to a representation of shapes by means of sequences of salient points. Experiments with a standard shape database reveal that correspondingly trained HMMs allow for robust classification. Finally, using spectral clustering, tree-based models also enable the extraction of larger, semantically meaningful, salient parts of shapes. [ABSTRACT FROM AUTHOR]

This paper presents a fast multispectral texture defect detection method based on the underlying three-dimensional spatial probabilistic image model. The model first adaptively learns its parameters on the flawless texture part and subsequently checks for texture defects using the recursive prediction analysis. We provide colour textile defect detection results that indicate the advantages of the proposed method. [ABSTRACT FROM AUTHOR]

In content based image retrieval, relevance feedback has been extensively studied to bridge the gap between low level image features and high level semantic concepts. However, it is still challenged by small sample size problem, since users are usually not so patient to label a large number of training instances. In this paper, two strategies are proposed to tackle this problem: (1) a novel active selection criterion. It takes into consideration both the informative and the representative measures. With this criterion, the diversities of the selected images are increased while their informative powers are kept, thus more information gain can be obtained from the feedback images; and (2) incorporation of unlabeled images within the co-training framework. Unlabeled data partially alleviates the training data scarcity problem, thus can improve the efficiency of SVM active learning. Systematic experimental results verify the superiority of our method over some existing active learning methods. [ABSTRACT FROM AUTHOR]

Spam e-mail with advertisement text embedded in images presents a great challenge to anti-spam filters. In this paper, we present a fast method to detect image-based spam e-mail. Using simple edge-based features, the method computes a vector of similarity scores between an image and a set of templates. This similarity vector is then used with support vector machines to separate spam images from other common categories of images. Our method does not require expensive OCR or even text extraction from images. Empirical results show that the method is fast and has good classification accuracy. [ABSTRACT FROM AUTHOR]

A prior probability model is adapted to a class of images by identification, or parameter estimation from training data. We propose a new and accurate analytical identification of a generic Markov-Gibbs random field (MGRF) model with multiple pairwise interaction and use it for structural analysis and synthesis of textures. [ABSTRACT FROM AUTHOR]

An improper design of feature selection methods can often lead to incorrect conclusions. Moreover, it is not generally realised that functional values of the criterion guiding the search for the best feature set are random variables with some probability distribution. This contribution examines the influence of several estimation techniques on the consistency of the final result. We propose an entropy based measure which can assess the stability of feature selection methods with respect to perturbations in the data. Results show that filters achieve a better stability and performance if more samples are employed for the estimation, i.e., using leave-one-out cross-validation, for instance. However, the best results for wrappers are acquired with the 50/50 holdout validation. [ABSTRACT FROM AUTHOR]

In this paper, we propose an approach to classify the film categories by using low-level features and visual features. The goal of this approach is to classify the films into genres. Our current domain of study is the movie preview. A film preview often emphasizes the theme of a film and hence provides suitable information for classification process. In our approach, we classify films into three broad categories: Action, Dramas, and Thriller films. Four computable video features (average shot length, color variance, motion content and lighting key) and visual effects are combined in our approach to provide the advantage information to demonstrate the movie category. Our approach can also be extended for other potential applications, including browsing, retrieval of videos on the internet, video-on-demand, and video libraries. [ABSTRACT FROM AUTHOR]

This paper builds upon a previous texture feature selection and classification methodology by extending it with two state-of-the-art fami lies of texture feature extraction methods, namely Manjunath & Ma's Gabor wavelet filters and Local Binary Pattern operators (LBP), which are integrated with more classical families of texture filters, such as co-occur rence matrices, Laws filters and wavelet transforms. Results with Brodatz compositions and outdoor images are evaluated and discussed, being the basis for a comparative study about the discrimination capabilities of those different families of texture methods, which have been traditionally applied on their own. [ABSTRACT FROM AUTHOR]

The lower the resolution of a given text is, the more difficult it becomes to segment and to recognize it. The resolution of screen-rendered text can be very low. With a typical x-height of 4 to 7 pixels it is much lower as in other low resolution OCR situations. Modern OCR approaches for such very low resolution text use a classification-based segmentation where the underlying classifier plays an important role. This paper presents a multiple classifier system for the classification of single characters. This system is used as a subsystem for the classification-based segmentation within a system to read screen-rendered text. The paper shows that the presented multiple classifier system outperforms the best former single classifier system on single characters by far and it shows the impact of using the multiple classifier system on the word reading performance. [ABSTRACT FROM AUTHOR]

A local adaptive restoration technique using a sliding discrete cosine transform (DCT) is presented. A minimum mean-square error estimator in the domain of a sliding DCT for image restoration is derived. The local restoration is performed by pointwise modification of local DCT coefficients. To provide image processing in real time, a fast recursive algorithm for computing the sliding DCT is utilized. The algorithm is based on a recursive relationship between three subsequent local DCT spectra. Computer simulation results using a real image are provided and compared with that of common restoration techniques. [ABSTRACT FROM AUTHOR]

In the present study, a new gridding method based on continuous wavelet transform (CWT) was performed. Line profiles of x and y axis were calculated, resulting to 2 different signals. These signals were independently processed by means of CWT at 15 different levels, using daubechies 4 mother wavelet. A summation, point by point, was performed on the processed signals, in order to suppress noise and enhance spot's differences. Additionally, a wavelet based hard thresholding filter was applied to each signal for the task of alleviating the noise of the signals. 14 real microarray images were used in order to visually assess the performance of our gridding method. Each microarray image contained 4 sub-arrays, each sub-array 40x40 spots, thus, 6400 spots totally. Moreover, these images contained contamination areas. According to our results, the accuracy of our algorithm was 98% in all 14 images and in all spots. Additionally, processing time was less than 3 sec on a 1024×1024×16 microarray image, rendering the method a promising technique for an efficient and fully automatic gridding processing. [ABSTRACT FROM AUTHOR]

We present a multiscale, graph-based approach to 3D image analysis using diffusion wavelet bases, which were presented in [1]. Diffusion wavelets allow to obtain orthonormal bases of L2 functions on graphs. This permits the study of classical wavelet algorithms (such as compression and denoising of functions in , , via nonlinear approximation) in this setting. In this paper, we describe how this could be used in structure-preserving compression of image sequences, modelled as a whole as a weighted graph, as a first step towards structural spatiotemporal wavelet segmentation. We further discuss the possibilities for using this abstract approach in computer vision tasks. [ABSTRACT FROM AUTHOR]

This paper presents a novel texture descriptor based on the wavelet transform. First, we will consider vertical and horizontal coefficients at the same position as the components of a bivariate random vector. The magnitud and angle of these vectors are computed and its histograms are analyzed. This empirical magnitud histogram is modelled by using a gamma distribution (pdf). As a result, the feature extraction step consists of estimating the gamma parameters using the maxima likelihood estimator and computing the circular histograms of angles. The similarity measurement step is done by means of the well-known Kullback-Leibler divergence. Finally, retrieval experiments are done using the Brodatz texture collection obtaining a good performance of this new texture descriptor. We compare two wavelet transforms, with and without downsampling, and show the advantage of the second one, which is translation invariant, for the construction of our texture descriptor. [ABSTRACT FROM AUTHOR]

Terahertz Computed Tomography (THz-CT) is a form of optical coherent tomography, which offers a promising approach for achieving non-invasive inspection of solid materials, with potentially numerous applications in industrial manufacturing and biomedical engineering. With traditional CT techniques such as X-ray tomography, full exposure data are needed to produce cross sectional images, even if the region of interest is small. For time-domain terahertz measurements, the requirement for full exposure data is impractical due to the slow measurement process. In this paper, we apply a wavelet-based algorithm to locally reconstruct THz-CT images with a significant reduction in the required measurements. The algorithm recovers an approximation of the region of interest from terahertz measurements within its vicinity, and thus improves the feasibility of using terahertz imaging to detect defects in solid materials and diagnose disease states for clinical practice. [ABSTRACT FROM AUTHOR]

cDNA micro arrays are more and more frequently used in molecular biology as they can give insight into the relation of an organism's metabolism and its genome. The process of imaging a micro array sample can introduce a great deal of noise and bias into the data with higher variance than the original signal which may swamp the useful information. As imperfections and fabrication artifacts often impair our ability to measure accurately the quantities of interest in micro array images, image processing for analysis of these images is an important and challenging problem. How to eliminate the effect of the noise imposes a challenging problem in micro array analysis. In this paper we implemented a novel algorithm for image sifting which could remove objects with definite size from macro array images. We used regular moving grids to sift noise object and obtained clean images for segmentation. The results have been compared with SWT, DWT and wiener filter denoising. [ABSTRACT FROM AUTHOR]

This paper introduces a novel shape matching approach for the automatic identification of real world objects in complex scenes. The identification process is applied on isolated objects and requires the segmentation of the image into separate objects, followed by the extraction of representative shape features and the similarity estimation of pairs of objects. In order to enable an efficient object representation, a novel boundary-based shape descriptor is introduced, formed by a set of one dimensional signals called shape signatures. During identification, the cross-correlation metric is used in a novel fashion to gauge the degree of similarity between objects. The invariance of the method to uniform-scaling and partial occlusion is achieved by considering both cases as possible scenarios when correlating shape signatures. The proposed vision system is robust to ambient conditions (partial occlusion) and image transformations (scaling, rotation, translation). The performance of the identifier has been examined in a great range of complex image and prototype object selections. [ABSTRACT FROM AUTHOR]

We describe a model for tree crown extraction from aerial images, a problem of great practical importance for the forestry industry. The novelty lies in the prior model of the region occupied by tree crowns in the image, which is a phase field version of the higher-order active contour inflection point ‘gas of circles' model. The model combines the strengths of the inflection point model with those of the phase field framework: it removes the ‘phantom circles' produced by the original ‘gas of circles' model, while executing two orders of magnitude faster than the contour-based inflection point model. The model has many other areas of application e.g. , to imagery in nanotechnology, biology, and physics. [ABSTRACT FROM AUTHOR]

Approaches based on obtaining relevant information from overwhelmingly large sets of measures have been recently adopted as an alternative to specialized features. In this work, we address the problem of finding a relevant subset of features and a suitable rotation (combined feature selection and feature extraction) as a weighted rotation. We focus our attention on two types of rotations: Weighted Principal Component Analysis and Weighted Regularized Discriminant Analysis. The objective function is the maximization of the J4 ratio. Tests were carried out on artificially generated classes, with several non-relevant features. Real data tests were also performed on segmentation of naildfold capillaroscopic images, and NIST-38 database (prototype selection). [ABSTRACT FROM AUTHOR]

On top of the prediction modes defined in the H.264/AVC standard, Scalable Video Coding defines prediction modes for inter-layer prediction. These inter-layer prediction modes allow the re-use of coded data from the base layer, at the cost of increasing the search space at the encoder and as a result increase the encoding time. In this paper, we investigate the relation between the coding decisions taken in the base layer and the enhancement layer. Our tests have shown that a number of relations can be clearly identified. We have observed that the co-located macroblock of a base layer macroblock coded in P_8x8 mode has a 40 % chance of being coded in P_8x8 mode as well. Further, we have observed that the P_Skip mode is only used when the quantization parameter in the enhancement layer is high. For macroblocks coded in B_Skip mode, the co-located macroblock in the enhancement layer will be coded in the B_Skip mode when it is highly quantized (probability of 63 % to 92 % for quantization parameter 30). These observations can be used to construct a model for fast mode decision in SVC. [ABSTRACT FROM AUTHOR]

We consider how continuous-time quantum walks can be used for graph matching, both exact and inexact, and measuring graph similarity. Our approach is to simulate the quantum walk on the two graphs in parallel by using an auxiliary graph that incorporates both graphs. The auxiliary graph allows quantum interference to take place between the two walks. Modelling the resultant interference amplitudes, which result from the differences in the two walks, we calculate probabilities for matches between pairs of vertices from the graphs. Using the Hungarian algorithm on these probabilities we recover a mapping between the graphs. To calculate graph similarity, we combine these probabilities with edge consistency information to give a consistency measure. We analyse our approach experimentally using synthetic graphs. [ABSTRACT FROM AUTHOR]

This paper presents a novel visual speech recognition approach based on motion segmentation and hidden Markov models (HMM). The proposed method identifies utterances from mouth video, without evaluating voice signals. The facial movements in the video data are represented using 2D spatial-temporal templates (STT). The proposed technique combines discrete stationary wavelet transform (SWT) and Zernike moments to extract rotation invariant features from the STTs. HMMs are used as speech classifier to model English phonemes. The preliminary results demonstrate that the proposed technique is suitable for phoneme classification with a high accuracy. [ABSTRACT FROM AUTHOR]

In this article we present a method to register image sequences taken at long time intervals.We suggest an improvement to Wards registration method for high dynamic range images to achieve limited sub-pixel accuracy. We show the chosen method to be appropriate even for heavily changing lighting conditions. [ABSTRACT FROM AUTHOR]

Dynamic Programming (DP) matching has been applied to solve distortion in spectral-based fingerprint recognition. However, spectral data is redundant, and its size is huge. PCA could be used to reduce the data size, but leads to loss of topographical information in projected vectors. This allows only inter-vector similarity estimations such as Euclid or Mahalanobis distances, and proves to be inadequate in presence of distortion occurring in finger sweeping with a line sensor. In this paper, we propose a novel two-step PCA to extract compact eigenfeatures amenable to DP matching. The first PCA extracts eigenfeatures of Fourier spectra from each image line. The second extracts eigenfeatures from all lines to form the feature templates. In matching, the feature templates are inversely transformed to line-by-line representations on the first PCA subspace for DP matching. Fingerprint matching experiments demonstrate the effectiveness of our proposed approach in template size reduction and accuracy improvement. [ABSTRACT FROM AUTHOR]

This paper presents a new hybrid split-and-merge image segmentation method based on computational geometry and topology using persistent homology. The algorithm uses edge-directed topology to initially split the image into a set of regions based on the Delaunay triangulations of the points in the edge map. Persistent homology is used to generate three types of regions: p-persistent regions, p-transient regions, and d-triangles. The p-persistent regions correspond to core objects in the image, while p-transient regions and d-triangles are smaller regions that may be combined in the merge phase, either with p-persistent regions to refine the core or with other p-transient and d-triangles regions to potentially form new core objects. Performing image segmentation based on topology and persistent homology guarantees several nice properties, and initial results demonstrate high quality image segmentation. [ABSTRACT FROM AUTHOR]

The eccentricity transform associates to each point of a shape the shortest distance to the point farthest away from it. It is defined in any dimension, for open and closed manyfolds. Top-down decomposition of the shape can be used to speed up the computation, with some partitions being better suited than others. We study basic convex shapes and their decomposition in the context of the continuous eccentricity transform. We show that these shapes can be decomposed for a more efficient computation. In particular, we provide a study regarding possible decompositions and their properties for the ellipse, the rectangle, and a class of elongated shapes. [ABSTRACT FROM AUTHOR]

This paper presents a performance evaluation of a set of fast block matching motion estimation methods of recent development. These methods are Kite-Cross-Diamond search (KCDS), Cross-Diamond-Hexagonal search (CDHS), Efficient-Hexagonal-Inner search (EHIS) and a newly proposed in this paper, called Cross-Half-Diamond low resolution search (CHDS), which is an improvement of Cross-Diamond-Hexagonal search. Also, Diamond search (DS) and Full search (FS) algorithms are implemented. These methods are evaluated based on the mean square error and the number of search points. Based on experimental results, it is concluded that DS, CDHS, CHDS and EHIS are appropriate for small and large motion contents, except EHIS for high frequencies and complex motion contents. The KCDS method has the lowest performance compared with other algorithms. [ABSTRACT FROM AUTHOR]

The aim of this work is to code the string matching problem as an optimization task and carrying out this optimization problem by means of a Hopfield neural network. The proposed method uses TCNN, a Hopfield neural network with decaying self-feedback, to find the best-matching (i.e., the lowest global distance) path between an input and a template. The proposed method is more than ‘exact' string matching. For example wild character matches as well as character that never match may be used in either string. As well it can compute edit distance between the two strings. It shows a very good performance in various string matching tasks. [ABSTRACT FROM AUTHOR]

This paper addresses the problem of estimating the 3D rigid pose of a CT volume of an object from its 2D X-ray projections. We use maximization of mutual information, an accurate similarity measure for multi-modal and mono-modal image registration tasks. However, it is known that the standard mutual information measure only takes intensity values into account without considering spatial information and its robustness is questionable. In this paper, instead of directly maximizing mutual information, we propose to use a variational approximation derived from the Kullback-Leibler bound. Spatial information is then incorporated into this variational approximation using a Gibbs random field model. The newly derived similarity measure has a least-squares form and can be effectively minimized by a multi-resolution Levenberg-Marquardt optimizer. Experimental results are presented on X-ray and CT datasets of a plastic phantom and a cadaveric spine segment. [ABSTRACT FROM AUTHOR]

Although interfering (outlying) details complicate image re- cognition and retrieval, ‘soft masking' of outliers shows considerable promise for robust pixel-by-pixel image matching or reconstruction from principal components (PC). Modeling the differences between two images or between an image and its PC estimate (obtained as a projection onto a subspace of PCs) with a mixed distribution of random noise and outliers, the masks are produced by a simple iterative Expectation-Maximisation based procedure. Experiments with facial images (extracted from the MIT face database) demonstrate the efficiency of this approach. [ABSTRACT FROM AUTHOR]

Rigid 2D/3D image registration is a common strategy in medical image processing. In this paper we present an extended global optimization strategy for a rigid 2D/3D image registration that consists of three components: a combination of a global and a local optimizer, a combination of a multi-scale and a multi-resolution approach, and a combination of an in-plane and an out-of-plane registration. The global optimizer Adaptive Random Search is used to provide several coarse registration results on a low resolution level that are refined by the local optimizer Best Neighbor on a higher resolution level. We evaluate the performance and the precision of our registration algorithm using two phantom models. We could approve that all three components of our optimization strategy lead to an significant improvement of the registration. [ABSTRACT FROM AUTHOR]

Recently, the concept of consistent image registration has been introduced to refer to a set of algorithms that estimate both the direct and inverse deformation together, that is, they exchange the roles of the target and the scene images alternatively; it has been demonstrated that this technique improves the registration accuracy, and that the biological significance of the obtained deformations is also improved. When dealing with free form deformations, the inversion of the transformations obtained becomes computationally intensive. In this paper, we suggest the parametrization of such deformations by means of a cubic B-spline, and its approximated inversion using a highly efficient algorithm. The results show that the consistency constraint notably improves the registration accuracy, especially in cases of a heavy initial misregistration, with very little computational overload. [ABSTRACT FROM AUTHOR]

We present a new image registration algorithm that employs Phase Correlation Method (PCM) to align rotated and translated 3D images. First, we use PCM and cylindrical coordinate transform to estimate rotation angle that aligns two images that are mutually rotated around known axis. An improvement of this technique is given to eliminate influence of noise and image differences in non-ideal conditions. Finally, an iterative optimization procedure is proposed which uses these techniques in rigid body registration tasks. We study the performance of the algorithm in simulated experiment on MRI brain image. [ABSTRACT FROM AUTHOR]

The objective of this work is to show how geodesic propagation techniques known in mathematical morphology can be employed to reconstruct terrain surfaces, and more generally grid data, from contour maps. We present the so-called generalised geodesic distance that was briefly introduced in a previous article. The shortest paths defined by the generalised geodesic distance can be used to linearly interpolate a given set of contour lines. We extend this concept by incorporating the knowledge of slope values over the contours and perform either Hermite interpolation with this distance or linear interpolation, but with a new weighted geodesic propagation function. Experiments are carried out over synthetic elevation data for which they result in nicely interpolated surfaces. The methodology is generic in the sense that it could be used to reconstruct any 2D or 3D digitised shape from its boundaries. [ABSTRACT FROM AUTHOR]

In this paper a new method for matching and recognition of shapes extracted from images, based on the structure and skeleton of the shape, is proposed. In this method, a function called "velocity function" derived from the radius function is introduced and values of this function are calculated for skeletal points. At this point, each skeletal curve is transformed into a vector containing values of the velocity function calculated along the curve. Then a tree-like structure is extracted from the skeleton of the shape so that each leaf of the tree indicates a skeletal curve of the skeleton and a velocity vector as its descriptor. These vectors are matched in fine-grain level using dynamic programming method and in coarse-grain level, the tree-like structures are matched using a greedy approach. At the final stage, the difference between the shapes is determined by a distance value resulted from the two levels matching process. This distance is used as a measure for shape matching and recognition. Experiments are performed on two standard binary image database in the presence of various transformations. Results confirm the efficiency and high recognition rate of our method. [ABSTRACT FROM AUTHOR]

Chazelle's triangulation [1] forms today the common basis for linear-time Euclidean shortest path (ESP) calculations (where start and end point are given within a simple polygon). This paper provides an alternative method for subdividing a simple polygon into "basic shapes", using trapezoids instead of triangles. The authors consider the presented method as being substantially simpler than the linear-time triangulation method. However, it requires a sorting step (of a subset of vertices of the given simple polygon); all the other subprocesses are linear time. [ABSTRACT FROM AUTHOR]

We present a novel method to detect multimodal regions composed of linear structures and measure the orientations in these regions, i.e. at line X-sings, T-junctions and Y-forks. In such complex regions an orientation detector should unmix the contributions of the unimodal structures. In our approach we first define a (streamline) divergence metric and apply it to our streamline field to detect junctions. After this step we select all streamlines that intersect a circle of radius r around the junction twice, cluster the intersection points and compute the direction per cluster. This yields a multimodal descriptor of the local orientations in the vicinity of the detected junctions. The method is suited for global analysis and has moderate memory requirements. [ABSTRACT FROM AUTHOR]

In this paper, we propose a new methodology for extracting river networks from satellite images. It combines morphological generalised geodesic transformations with hydrological overland flow simulations. The method requires the prior generation of a geodesic mask and a marker image by applying a series of transformations to the original image. These images are then combined so as to produce a pseudo digital elevation model whose valleys match the desired networks. The performance of the methodology is demonstrated for the extraction of river networks from a single band of a Landsat image. The method is generic in the sense that it can be extended for the extraction of other types of arborescent networks such as blood vessels in medical images. [ABSTRACT FROM AUTHOR]

Segmentation methods based on deformable models have proved to be successful with difficult images, particularly those using genetic algorithms to minimize the energy function. Nevertheless, they are normally conceived as fully automatic, and not always generate satisfactory results. In this work, a method to include the information of fixed points whithin a contour detection system using point distribution models and genetic algorithms is presented. Also, an interactive scheme is proposed to take advantage of this technique. The method has been tested against a database of 93 cattle images, with a significant improvement in the success rate of the detections, from 61% up to 95%. [ABSTRACT FROM AUTHOR]

This paper describes a new approach for detection of curvilinear regions. These features detection can be useful for any matching based algorithm such as stereoscopic vision. Our detector is based on curvilinear structure model, defined observing the real world. Then, we propose a multi-scale search algorithm of curvilinear regions and we report some preliminary results. [ABSTRACT FROM AUTHOR]

In this paper we introduce a new method for computing the orientation for compound shapes. If the method is applied to single component shapes the computed orientation is consistent with the shape orientation defined by the axis of the least second moment of inertia. If the new method is applied to compound shapes this is not the case, and consequently the presented method is both new and different. [ABSTRACT FROM AUTHOR]

This paper reports about the development of two provably correct approximate algorithms which calculate the Euclidean shortest path (ESP) within a given cube-curve with arbitrary accuracy, defined by ε> 0, and in time complexity $\kappa(\varepsilon) \cdot {\cal O}(n)$, where κ(ε) is the length difference between the path used for initialization and the minimum-length path, divided by ε. A run-time diagram also illustrates this linear-time behavior of the implemented ESP algorithm. [ABSTRACT FROM AUTHOR]

Ellipse is one of the most common features that appears in images. Over years in research, real-timing and robustness have been two very challenging problems aspects of ellipse detection. Aiming to tackle them both, we propose an ellipse detection algorithm based on pseudo-random sample consensus (PRANSAC). In PRANSAC we improve a contour-based ellipse detection algorithm (CBED), which was presented in our previous work. In addition, the parallel thinning algorithm is employed to eliminate useless feature points, which increases the time efficiency of our detection algorithm. In order to further speed up, a 3-point ellipse fitting method is introduced. In terms of robustness, a "robust candidate sequence" is proposed to improve the robustness performance of our detection algorithm. Compared with the state-of-the-art ellipse detection algorithms, experimental results based on real application images show that significant improvements in time efficiency and performance robustness of the proposed algorithm have been achieved. [ABSTRACT FROM AUTHOR]

Active Shape Models often require a considerable number of training samples and landmark points on each sample, in order to be efficient in practice. We introduce the Fractal Active Shape Models, an extension of Active Shape Models using fractal interpolation, in order to surmount these limitations. They require a considerably smaller number of landmark points to be determined and a smaller number of variables for describing a shape, especially for irregular ones. Moreover, they are shown to be efficient when few training samples are available. [ABSTRACT FROM AUTHOR]

Thinning is an iterative layer by layer erosion for extracting skeleton. This paper presents an efficient parallel 3D thinning algorithm which produces medial surfaces. A three-subiteration strategy is proposed: the thinning operation is changed from iteration to iteration with a period of three according to the three deletion directions. [ABSTRACT FROM AUTHOR]

In this paper we introduce a new method for image segmentation. It is based on a height map generated from the input image. The height map characterizes the image content in such a way that the application of the watershed concept provides a proper segmentation of the image. The height map enables the watershed method to provide better segmentation results on difficult images, e.g., images of natural objects, than without the intermediate height map generation. Markers used for the watershed concept are generated automatically from the input data holding the advantage of a more autonomous segmentation. In addition, we introduce a new edge detector which has some advantages over the Canny edge detector. We demonstrate our methods by means of a number of segmentation examples. [ABSTRACT FROM AUTHOR]

An orientability measure determines how orientable a shape is; i.e. how reliable an estimate of its orientation is likely to be. This is valuable since many methods for computing orientation fail for certain shapes. In this paper several existing orientability measures are discussed and several new orientability measures are introduced. The measures are compared and tested on synthetic and real data. [ABSTRACT FROM AUTHOR]

This paper proposes a model-based method for intensity-based segmentation of images acquired from multiple modalities. Pixel intensity within a modality image is represented by a univariate Gaussian distribution mixture in which the components correspond to different segments. The proposed Multi-Modality Expectation-Maximization (MMEM) algorithm then estimates the probability of each segment along with parameters of the Gaussian distributions for each modality by maximum likelihood using the Expectation-Maximization (EM) algorithm. Multimodal images are simultaneously involved in the iterative parameter estimation step. Pixel classes are determined by maximising a posteriori probability contributed from all multimodal images. Experimental results show that the method exploits and fuses complementary information of multimodal images. Segmentation can thus be more precise than when using single-modality images. [ABSTRACT FROM AUTHOR]