Image segmentation is critically important in almost all medical image analysis for automatic interpretations and processing. However, it is often challenging to perform image segmentation due to data imbalance between intra- and inter-class, resulting in over- or under-segmentation. Consequently, we proposed a new methodology to address the above issue, with a compact yet effective contour-weighted loss function. Our new loss function incorporates a contour-weighted cross-entropy loss and separable dice loss. The former loss extracts the contour of target regions via morphological erosion and generates a weight map for the cross-entropy criterion, whereas the latter divides the target regions into contour and non-contour components through the extracted contour map, calculates dice loss separately, and combines them to update the network. We carried out abdominal organ segmentation and brain tumor segmentation on two public datasets to assess our approach. Experimental results demonstrated that our approach offered superior segmentation, as compared to several state-of-the-art methods, while in parallel improving the robustness of those popular state-of-the-art deep models through our new loss function. The code is available at https://github.com/ huangzyong/Contour-weighted-Loss-Seg.

The interpretation and analysis of Magnetic resonance imaging (MRI) benefit from high spatial resolution. Unfortunately, direct acquisition of high spatial resolution MRI is time-consuming and costly, which increases the potential for motion artifact, and suffers from reduced signal-to-noise ratio (SNR). Super-resolution reconstruction (SRR) is one of the most widely used methods in MRI since it allows for the trade-off between high spatial resolution, high SNR, and reduced scan times. Deep learning has emerged for improved SRR as compared to conventional methods. However, current deep learning-based SRR methods require large-scale training datasets of high-resolution images, which are practically difficult to obtain at a suitable SNR. We sought to develop a methodology that allows for dataset-free deep learning-based SRR, through which to construct images with higher spatial resolution and of higher SNR than can be practically obtained by direct Fourier encoding. We developed a dataset-free learning method that leverages a generative neural network trained for each specific scan or set of scans, which in turn, allows for SRR tailored to the individual patient. With the SRR from three short duration scans, we achieved high quality brain MRI at an isotropic spatial resolution of 0.125 cubic mm with six minutes of imaging time for T2 contrast and an average increase of 7.2 dB (34.2%) in SNR to these short duration scans. Motion compensation was achieved by aligning the three short duration scans together. We assessed our technique on simulated MRI data and clinical data acquired from 15 subjects. Extensive experimental results demonstrate that our approach achieved superior results to state-of-the-art methods, while in parallel, performed at reduced cost as scans delivered with direct high-resolution acquisition.

Correlation filtering-based visual tracking has achieved impressive success in terms of both tracking accuracy and computational efficiency. In this paper, a novel correlation filtering approach is proposed by means of joint learning to bridge the gap between the circulant filtering and the classical filtering methods. The circulant structure of tracking and the information from successive frames are simultaneously exploited in the proposed work. A new formulation for the correlation filter learning is proposed to enhance the discrimination of the learned filter by integrating both the kernel and the image feature domains. The proposed approach is computationally efficient since a closed-form solution is derived for the new formulation. Extensive experiments are conducted on two popular tracking benchmarks, and the experimental results demonstrate that the proposed tracker outperforms most of the state-of-the-art trackers.

Surgical resection is the main clinical method for the treatment of bone tumors. A critical procedure for bone tumor resection is to plan a set of cut planes that enable resecting the bone tumor with a safe margin while preserving the maximum amount of healthy bone. Currently, the surgeons rely on manual methods to plan the cut planes, which highly depend on the surgeons' experiences and have been demonstrated to be error-prone, and in turn, increase the recurrence rate or resect much healthy bone. This study targets on improving the precision of cut plane planning for the image guided pelvis tumor resection surgeries. A semi-automatic approach to cut plane planning was proposed via a coarse-to-fine strategy. It can efficiently identify a dangerous region in the 3D space, which contains the bone tumor and its surrounding normal tissue with a safe margin. By projecting the dangerous region into an appropriate 2D space, a segmented boundary-constrained linear regression method was leveraged to plan a set of 3D cut planes that ensure the minimum area of the resected specimen in the 2D space while having the dangerous region cleared. Further, a coarse-to-fine 3D cut plane planning method was developed by incorporating a 3D cut plane refinement scheme with our 2D planning method. Extensive experiments, on the surgical data from nine previous pelvis tumor resection surgeries, demonstrated that our proposed approach substantially improved the localization precision of cut planes ( ) and decreased the amount of resected specimen ( ), as compared to the manual method.

This paper presents a novel visual tracking approach to correlation filter learning toward peak strength of correlation response. Previous methods leverage all features of the target and the immediate background to learn a correlation filter. Some features, however, may be distractive to tracking, like those from occlusion and local deformation, resulting in unstable tracking performance. This paper aims at solving this issue and proposes a novel algorithm to learn the correlation filter. The proposed approach, by imposing an elastic net constraint on the filter, can adaptively eliminate those distractive features in the correlation filtering. A new peak strength metric is proposed to measure the discriminative capability of the learned correlation filter. It is demonstrated that the proposed approach effectively strengthens the peak of the correlation response, leading to more discriminative performance than previous methods. Extensive experiments on a challenging visual tracking benchmark demonstrate that the proposed tracker outperforms most state-of-the-art methods.

In this paper, a novel spatial-temporal locality is proposed and unified via a discriminative dictionary learning framework for visual tracking. By exploring the strong local correlations between temporally obtained target and their spatially distributed nearby background neighbors, a spatial-temporal locality is obtained. The locality is formulated as a subspace model and exploited under a unified structure of discriminative dictionary learning with a subspace structure. Using the learned dictionary, the target and its background can be described and distinguished effectively through their sparse codes. As a result, the target is localized by integrating both the descriptive and the discriminative qualities. Extensive experiments on various challenging video sequences demonstrate the superior performance of proposed algorithm over the other state-of-the-art approaches.

How to build a robust and accurate appearance model is a crucial problem in object tracking. However, in most existing tracking methods, the structures among the adjacent video frames and neighboring regions, which may be helpful to improve the representation capability of the appearance model, have not been fully exploited. In this paper, we propose a novel tracking method by taking into account these structures to represent the appearance model. First, we propose a novel graph-regularized structured support vector machine (GS-SVM) algorithm by combining manifold learning and structured learning. Then, the proposed GS-SVM algorithm is employed to build the appearance model and a novel tracking method is developed. This new tracker not only absorbs the advantage of structured learning that deals with the intermediate classification step existing in tracking-by-detection methods, but also exploits the geometry structures in the tracked results and neighboring regions. In addition, a hybrid update strategy is introduced to fit with the GS-SVM-based appearance model. The experimental results demonstrate that the proposed tracking algorithm can outperform several state-of-the-art tracking methods in the benchmark dataset.

Object detection and tracking is an important research topic in computer vision with numerous practical applications. Although great progress has been made both in object detection and tracking, it is still a big challenge in automatic real-time applications. In this paper, a fast and robust approach is proposed by integrating an adaptive object detection technique within a kernelized correlation filter (KCF) framework. The KCF tracker is automatically initialized via salient object detection and localization. An adaptive object detection strategy is proposed to refine the location and boundary of the object when the tracking confidence value is below a certain threshold. In addition, a reliable post-processing technique is designed to accurately localize the object from a saliency map. Extensive quantitative and qualitative experiments on the challenging datasets have been performed to verify the proposed approach, which also demonstrates that our approach greatly outperforms the state-of-the-art methods in terms of tracking speed and accuracy.

Good tracking performance is in general attributed to accurate representation over previously obtained targets or reliable discrimination between the target and the surrounding background. In this work, we exploit the advantages of the both approaches to achieve a robust tracker. We construct a subspace to represent the target and the neighboring background, and simultaneously propagate their class labels via the learned subspace. Moreover, we propose a novel criterion to identify the target from numerous target candidates on each frame, which takes into account both discrimination reliability and representation accuracy. In addition, with the proposed criterion, the ambiguity in the class labels of the neighboring background samples, which often influences the reliability of discriminative tracking model, is effectively alleviated, while the training set is still kept small. Extensive experiments demonstrate that our tracker performs favourably against many other state-of-the-art trackers.

We propose a new target representation method, where the temporally obtained targets are jointly represented as a time series function by exploiting their spatially local structure. With this method, we propose a new tracking algorithm, where tracking is formulated as a problem of Gaussian process regression over the joint representation. Numerous experiments on various challenging video sequences demonstrate that our tracker outperforms several other state-of-the-art trackers.

Target representation is a necessary component for a robust tracker. However, during tracking, many complicated factors may make the accumulated errors in the representation significantly large, leading to tracking drift. This paper aims to improve the robustness of target representation to avoid the influence of the accumulated errors, such that the tracker only acquires the information that facilitates tracking and ignores the distractions. We observe that the locally mutual relations between the feature observations of temporally obtained targets are beneficial to the subspace representation in visual tracking. Thus, we propose a novel subspace learning algorithm for visual tracking, which imposes joint row-wise sparsity structure on the target subspace to adaptively exclude distractive information. The sparsity is induced by exploiting the locally mutual relations between the feature observations during learning. To this end, we formulate tracking as a subspace sparsity inducing problem. A large number of experiments on various challenging video sequences demonstrate that our tracker outperforms many other state-of-the-art trackers.

Single object tracking, in which a target is often initialized manually in the first frame and then is tracked and located automatically in the subsequent frames, is a hot topic in computer vision. The traditional tracking-by-detection framework, which often formulates tracking as a binary classification problem, has been widely applied and achieved great success in single object tracking. However, there are some potential issues in this formulation. For instance, the boundary between the positive and negative training samples is fuzzy, and the objectives of tracking and classification are inconsistent. In this paper, we attempt to address the above issues from the fuzzy system perspective and propose a novel tracking method by formulating tracking as a fuzzy classification problem. First, we introduce the fuzzy strategy into tracking and propose a novel fuzzy tracking framework, which can measure the importance of the training samples by assigning different memberships to them and offer more strict spatial constraints. Second, we develop a fuzzy least squares support vector machine (FLS-SVM) approach and employ it to implement a concrete tracker. In particular, the primal form, dual form, and kernel form of FLS-SVM are analyzed and the corresponding closed-form solutions are derived for efficient realizations. Besides, a least squares regression model is built to control the update adaptively, retaining the robustness of the appearance model. The experimental results demonstrate that our method can achieve comparable or superior performance to many state-of-the-art methods.

How to build an accurate and reliable appearance model to improve the performance is a crucial problem in object tracking. Since the multi-view learning can lead to more accurate and robust representation of the object, in this paper, we propose a novel tracking method via multi-view learning framework by using multiple support vector machines (SVM). The multi-view SVMs tracking method is constructed based on multiple views of features and a novel combination strategy. To realize a comprehensive representation, we select three different types of features, i.e., gray scale value, histogram of oriented gradients (HOG), and local binary pattern (LBP), to train the corresponding SVMs. These features represent the object from the perspectives of description, detection, and recognition, respectively . In order to realize the combination of the SVMs under the multi-view learning framework, we present a novel collaborative strategy with entropy criterion, which is acquired by the confidence distribution of the candidate samples. In addition, to learn the changes of the object and the scenario, we propose a novel update scheme based on subspace evolution strategy. The new scheme can control the model update adaptively and help to address the occlusion problems . We conduct our approach on several public video sequences and the experimental results demonstrate that our method is robust and accurate, and can achieve the state-of-the-art tracking performance.