nils-herrmann/clean_scirepeval huggingface dataset:
Nonparametric information fusion for motion estimation

The problem of information fusion appears in many forms in vision. Tasks such as motion estimation, multimodal registration, tracking, and robot localization, often require the synergy of estimates coming from multiple sources. Most of the fusion algorithms, however, assume a single source model and are not robust to outliers. If the data to be fused follow different underlying models, the traditional algorithms would produce poor estimates. We present in this paper a nonparametric approach to information fusion called variable-bandwidth density-based fusion (VBDF). The fusion estimator is computed as the location of the most significant mode of a density function, which takes into account the uncertainty of the estimates to be fused. A mode detection scheme is presented, which relies on variable-bandwidth mean shift computed at multiple scales. We show that the proposed estimator is consistent and conservative, while handling naturally outliers in the data and multiple source models. The new theory is tested for the task of multiple motion estimation. Numerous experiments validate the theory and provide very competitive results.
Passing vehicle detection from dynamic background using robust information fusion

This work presents a robust method of passing vehicle detection. Obstacle detection algorithms that rely on motion estimation tend to be sensitive to image outliers caused by structured noise and shadows. To achieve a reliable vision system, we have developed two important techniques, motion estimation with robust information fusion and dynamic scene modeling. By exploiting the uncertainty of flow estimates, our information fusion scheme gives robust estimation of image motion. In addition, we also model the background and foreground dynamics of road scenes and impose coherency constraints to eliminate outliers. The proposed detection scheme is used by a single-camera vision system developed for driver assistance. Our test results have shown superior performance achieved by the new detection method.
Multi-Part Modeling and Segmentation of Left Atrium in C-Arm CT for Image-Guided Ablation of Atrial Fibrillation

As a minimally invasive surgery to treat atrial fibrillation (AF), catheter based ablation uses high radio-frequency energy to eliminate potential sources of abnormal electrical events, especially around the ostia of pulmonary veins (PV). Fusing a patient-specific left atrium (LA) model (including LA chamber, appendage, and PVs) with electro-anatomical maps or overlaying the model onto 2-D real-time fluoroscopic images provides valuable visual guidance during the intervention. In this work, we present a fully automatic LA segmentation system on nongated C-arm computed tomography (C-arm CT) data, where thin boundaries between the LA and surrounding tissues are often blurred due to the cardiac motion artifacts. To avoid segmentation leakage, the shape prior should be exploited to guide the segmentation. A single holistic shape model is often not accurate enough to represent the whole LA shape population under anatomical variations, e.g., the left common PVs vs. separate left PVs. Instead, a part based LA model is proposed, which includes the chamber, appendage, four major PVs, and right middle PVs. Each part is a much simpler anatomical structure compared to the holistic one and can be segmented using a model-based approach (except the right middle PVs). After segmenting the LA parts, the gaps and overlaps among the parts are resolved and segmentation of the ostia region is further refined. As a common anatomical variation, some patients may contain extra right middle PVs, which are segmented using a graph cuts algorithm under the constraints from the already extracted major right PVs. Our approach is computationally efficient, taking about 2.6 s to process a volume with 256 × 256 × 245 voxels. Experiments on 687 C-arm CT datasets demonstrate its robustness and state-of-the-art segmentation accuracy.
Bimodal system for interactive indexing and retrieval of pathology images

The prototype of a system to assist the physicians in differential diagnosis of lymphoproliferative disorders of blood cells from digitized specimens is presented. The user selects the region of interest (ROI) in the image which is then analyzed with a fast, robust color segmenter. Queries in a database of validated cases can be formulated in terms of shape (similarity invariant Fourier descriptors), texture (multiresolution simultaneous autoregressive model), color (L*u*/spl upsi/* space), and area, derived from the delineated ROI. The uncertainty of the segmentation process (obtained through a numerical method) determines the accuracy of shape description (number of Fourier harmonics). Ten-fold cross-validated classification over a database of 261 color 640/spl times/480 images was implemented to assess the system performance. The ground truth was obtained through immunophenotyping by flow cytometry. To provide a natural man-machine interface, most input commands are bimodal: either using the mouse or by voice. A speech synthesizer provides feedback to the user. All the employed computational modules are context independent and thus the same system can be used in a large variety of application domains.
An information fusion framework for robust shape tracking

Existing methods for incorporating subspace model constraints in shape tracking use only partial information from the measurements and model distribution. We propose a unified framework for robust shape tracking, optimally fusing heteroscedastic uncertainties or noise from measurement, system dynamics, and a subspace model. The resulting nonorthogonal subspace projection and fusion are natural extensions of the traditional model constraint using orthogonal projection. We present two motion measurement algorithms and introduce alternative solutions for measurement uncertainty estimation. We build shape models offline from training data and exploit information from the ground truth initialization online through a strong model adaptation. Our framework is applied for tracking in echocardiograms where the motion estimation errors are heteroscedastic in nature, each heart has a distinct shape, and the relative motions of epicardial and endocardial borders reveal crucial diagnostic features. The proposed method significantly outperforms the existing shape-space-constrained tracking algorithm. Due to the complete treatment of heteroscedastic uncertainties, the strong model adaptation, and the coupled tracking of double-contours, robust performance is observed even on the most challenging cases.
An integrated framework of vision-based vehicle detection with knowledge fusion

This paper describes an integrated framework of on-road vehicle detection through knowledge fusion. In contrast to appearance-based detectors that make instant decisions, the proposed detection framework fuses appearance, geometry and motion information over multiple image frames. The knowledge of vehicle/non-vehicle appearance, scene geometry and vehicle motion is utilized through prior models obtained by learning, modeling and estimation algorithms. It is shown that knowledge fusion largely improves the robustness and reliability of the detection system.
Detection and retrieval of cysts in joint ultrasound B-mode and elasticity breast images

Distinguishing cysts from other tumors is a routine clinical practice for diagnosing breast cancer. It has shown that more accurate diagnosis can be achieved by combining elasticity images with traditional B-mode ultrasound images . In this paper, we propose a fully automatic system to detect cysts jointly in both B-mode and elasticity images. It is based on database-guided techniques that learn the knowledge of cyst appearance automatically from B-mode and elasticity images in a database. Further, for a detected cyst in a query image, the cysts with similar image appearance in the database are retrieved to improve diagnostic accuracy and confidence. In the experiment, we show that our system achieves high sensitivity and specificity in cyst diagnosis.
Hierarchical, learning-based automatic liver segmentation

In this paper we present a hierarchical, learning-based approach for automatic and accurate liver segmentation from 3D CT volumes. We target CT volumes that come from largely diverse sources (e.g., diseased in six different organs) and are generated by different scanning protocols (e.g., contrast and non-contrast, various resolution and position). Three key ingredients are combined to solve the segmentation problem. First, a hierarchical framework is used to efficiently and effectively monitor the accuracy propagation in a coarse-to-fine fashion. Second, two new learning techniques, marginal space learning and steerable features, are applied for robust boundary inference. This enables handling of highly heterogeneous texture pattern. Third, a novel shape space initialization is proposed to improve traditional methods that are limited to similarity transformation. The proposed approach is tested on a challenging dataset containing 174 volumes. Our approach not only produces excellent segmentation accuracy, but also runs about fifty times faster than state-of-the-art solutions [7, 9].
A boosting regression approach to medical anatomy detection

The state-of-the-art object detection algorithm learns a binary classifier to differentiate the foreground object from the background. Since the detection algorithm exhaustively scans the input image for object instances by testing the classifier, its computational complexity linearly depends on the image size and, if say orientation and scale are scanned, the number of configurations in orientation and scale. We argue that exhaustive scanning is unnecessary when detecting medical anatomy because a medical image offers strong contextual information. We then present an approach to effectively leveraging the medical context, leading to a solution that needs only one scan in theory or several sparse scans in practice and only one integral image even when the rotation is considered. The core is to learn a regression function, based on an annotated database, that maps the appearance observed in a scan window to a displacement vector, which measures the difference between the configuration being scanned and that of the target object. To achieve the learning task, we propose an image-based boosting ridge regression algorithm, which exhibits good generalization capability and training efficiency. Coupled with a binary classifier as a confidence scorer, the regression approach becomes an effective tool for detecting left ventricle in echocardiogram, achieving improved accuracy over the state-of-the-art object detection algorithm with significantly less computation.
Training set synthesis for entropy-constrained transform vector quantization

This paper introduces the concept of training set synthesis for entropy-constrained transform vector quantization (TSS-ECTVQ). The statistics of actual sets of transform vectors are first approximated using histograms. New sets of vectors-called synthesized training sets-are obtained based upon the estimated parameters-called training set parameters. By employing a fast entropy-constrained algorithm, codebooks are populated from the synthesized training sets for each image being coded. Then, entropy-constrained vector quantization is performed. The training set parameters are sent to the decoder, which obtains the same training sets, and generates codebooks identical to the encoder. Experimental results demonstrate that high quality image coding at low bit rates can be obtained with the proposed TSS-ECTVQ method. In particular, the image Lenna was coded at 0.25 bits/pixel with a PSNR of 32.42 dB.
Fast Automatic Heart Chamber Segmentation from 3D CT Data Using Marginal Space Learning and Steerable Features

Multi-chamber heart segmentation is a prerequisite for global quantification of the cardiac function. The complexity of cardiac anatomy, poor contrast, noise or motion artifacts makes this segmentation problem a challenging task. In this paper, we present an efficient, robust, and fully automatic segmentation method for 3D cardiac computed tomography (CT) volumes. Our approach is based on recent advances in learning discriminative object models and we exploit a large database of annotated CT volumes. We formulate the segmentation as a two step learning problem: anatomical structure localization and boundary delineation. A novel algorithm, marginal space learning (MSL), is introduced to solve the 9-dimensional similarity search problem for localizing the heart chambers. MSL reduces the number of testing hypotheses by about six orders of magnitude. We also propose to use steerable image features, which incorporate the orientation and scale information into the distribution of sampling points, thus avoiding the time-consuming volume data rotation operations. After determining the similarity transformation of the heart chambers, we estimate the 3D shape through learning-based boundary delineation. Extensive experiments on multi-chamber heart segmentation demonstrate the efficiency and robustness of the proposed approach, comparing favorably to the state-of-the-art. This is the first study reporting stable results on a large cardiac CT dataset with 323 volumes. In addition, we achieve a speed of less than eight seconds for automatic segmentation of all four chambers.
Conditional density learning via regression with application to deformable shape segmentation

Many vision problems can be cast as optimizing the conditional probability density function p(C\I) where I is an image and C is a vector of model parameters describing the image. Ideally, the density function p(C\I) would be smooth and unimodal allowing local optimization techniques, such as gradient descent or simplex, to converge to an optimal solution quickly, while preserving significant nonlinearities of the model. We propose to learn a conditional probability density satisfying these desired properties for the given training data set. To do this, we formulate a novel regression problem that finds a function approximating the target density. Learning the regressor is challenging due to the high dimensionality of model parameters, C, and the complexity of relating the image and the model. Our approach makes two contributions. First, we take a multilevel refinement approach by learning a series of density functions, each of which guides the solution of optimization algorithms increasingly converging to the correct solution. Second, we propose a new data sampling algorithm that takes into account the gradient information of the target function. We have applied this learning approach to deformable shape segmentation and have achieved better accuracy than the previous methods.
Learning-based 3D myocardial motion flowestimation using high frame rate volumetric ultrasound data

The estimation and analysis of cardiac motion provides important information for the quantification of the elasticity and contractility of the myocardium. Taking advantage of the recent progress on real-time ultrasound imaging, unstitched volumetric data can be captured in a high frame rate. In this paper, we propose a learning-based method to automatically estimate the 3D displacements and velocities of the myocardial motion. To achieve robust tracking on ultrasound image sequences, multiple information is fused together in our framework to handle noisy and missing data, including speckle patterns, boundary detection and motion prediction. Preliminary results on clinical data confirmed these findings in a qualitative manner. The estimated displacement and velocity values have a strong agreement with the results from other systems and modalities. The proposed method is efficient and achieves high speed performance of less than 1 second per frame for volumetric ultrasound data.
Robust detection and tracking of human faces with an active camera

We present an efficient framework for the detection and tracking of human faces with an active camera. The Bhattacharyya coefficient is employed as a similarity measure between the color distribution of the face model and face candidates. The proper derivation of these distributions allows the use of the spatial gradient of the Bhattacharyya coefficient to guide a fast search for the best face candidate. The optimization, which is based on mean shift analysis, requires only a few iterations to converge. Scale changes of the tracked face are handled by exploiting the scale invariance of the similarity measure and the luminance gradient computed on the border of the hypothesized face region. The detection and tracking modules are almost-identical, the difference being that the detection involves mean shift optimization with multiple initializations. Our dual-mode implementation of the camera controller determines the pan, tilt, and zoom camera to switch between smooth pursuit and saccadic movements, as a function of the target presence in the fovea region. The resulting system runs in real-time on a standard PC, being robust to partial occlusion, clutter, face scale variations, rotations in depth, and fast-changes in subject/camera position.
Shape-based image indexing and retrieval for diagnostic pathology

A prototype system performing analysis, indexing and retrieval of pathology images to assist physicians in differential diagnosis of lymphoproliferative disorders is presented. Robust color segmentation is used to automatically analyse regions of interest in images of leukocytes. The shape of leukocyte nuclei, described through similarity invariant shape descriptors, represents the main attribute in the search query. Monte Carlo tests for stability and goal-directed evaluations of the system performance are also shown.
Deep Decision Network for Multi-class Image Classification

In this paper, we present a novel Deep Decision Network (DDN) that provides an alternative approach towards building an efficient deep learning network. During the learning phase, starting from the root network node, DDN automatically builds a network that splits the data into disjoint clusters of classes which would be handled by the subsequent expert networks. This results in a tree-like structured network driven by the data. The proposed method provides an insight into the data by identifying the group of classes that are hard to classify and require more attention when compared to others. DDN also has the ability to make early decisions thus making it suitable for timesensitive applications. We validate DDN on two publicly available benchmark datasets: CIFAR-10 and CIFAR-100 and it yields state-of-the-art classification performance on both the datasets. The proposed algorithm has no limitations to be applied to any generic classification problems.
A framework for personalization of coronary flow computations during rest and hyperemia

We introduce a Computational Fluid Dynamics (CFD) based method for performing patient-specific coronary hemodynamic computations under two conditions: at rest and during drug-induced hyperemia. The proposed method is based on a novel estimation procedure for determining the boundary conditions from non-invasively acquired patient data at rest. A multi-variable feedback control framework ensures that the computed mean arterial pressure and the flow distribution matches the estimated values for an individual patient during the rest state. The boundary conditions at hyperemia are derived from the respective rest-state values via a transfer function that models the vasodilation phenomenon. Simulations are performed on a coronary tree where a 65% diameter stenosis is introduced in the left anterior descending (LAD) artery, with the boundary conditions estimated using the proposed method. The results demonstrate that the estimation of the hyperemic resistances is crucial in order to obtain accurate values for pressure and flow rates. Results from an exhaustive sensitivity analysis have been presented for analyzing the variability of trans-stenotic pressure drop and Fractional Flow Reserve (FFR) values with respect to various measurements and assumptions.
Semantic-based indexing of fetal anatomies from 3-D ultrasound data using global/semi-local context and sequential sampling

The use of 3-D ultrasound data has several advantages over 2-D ultrasound for fetal biometric measurements, such as considerable decrease in the examination time, possibility of post-exam data processing by experts and the ability to produce 2-D views of the fetal anatomies in orientations that cannot be seen in common 2-D ultrasound exams. However, the search for standardized planes and the precise localization of fetal anatomies in ultrasound volumes are hard and time consuming processes even for expert physicians and sonographers. The relative low resolution in ultrasound volumes, small size of fetus anatomies and inter-volume position, orientation and size variability make this localization problem even more challenging. In order to make the plane search and fetal anatomy localization problems completely automatic, we introduce a novel principled probabilistic model that combines discriminative and generative classifiers with contextual information and sequential sampling. We implement a system based on this model, where the user queries consist of semantic keywords that represent anatomical structures of interest. After queried, the system automatically displays standardized planes and produces biometric measurements of the fetal anatomies. Experimental results on a held-out test set show that the automatic measurements are within the inter-user variability of expert users. It resolves for position, orientation and size of three different anatomies in less than 10 seconds in a dual-core computer running at 1.7 GHz.
Kernel-based Bayesian filtering for object tracking

Particle filtering provides a general framework for propagating probability density functions in nonlinear and non-Gaussian systems. However, the algorithm is based on a Monte Carlo approach and sampling is a problematic issue, especially for high dimensional problems. This paper presents a new kernel-based Bayesian filtering framework, which adopts an analytic approach to better approximate and propagate density functions. In this framework, the techniques of density interpolation and density approximation are introduced to represent the likelihood and the posterior densities by Gaussian mixtures, where all parameters such as the number of mixands, their weight, mean, and covariance are automatically determined. The proposed analytic approach is shown to perform sampling more efficiently in high dimensional space. We apply our algorithm to real-time tracking problems, and demonstrate its performance on real video sequences as well as synthetic examples.
AutoMPR: Automatic detection of standard planes in 3D echocardiography

3D echocardiography is one of the emerging real-time imaging modalities that is increasingly used in clinical practice to assess cardiac functions. It provides a more complete heart representation for evaluation in comparison to conventional 2D echocardiography. However, one of the drawbacks is the time it takes clinicians to navigate the 3D volumes to the anatomy of interest and to obtain standardized views that are similar to the 2D acquisitions. We propose an automated supervised learning method to detect standard multiplanar reformatted planes (MPRs) from a 3D echocardiographic volume. Extensive evaluations on a database of 326 volumes show performance comparable to intra-user variability and the execution time of the algorithm is about 2 seconds.