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22
Quasilinear algorithms for the topological watershed
 JOURNAL OF MATHEMATICAL IMAGING AND VISION
, 2005
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Efficient maximally stable extremal region (mser) tracking
 IEEE International Conference on Computer Vision and Pattern Recognition
"... This paper introduces a tracking method for the well known local MSER (Maximally Stable Extremal Region) detector. The component tree is used as an efficient data structure, which allows the calculation of MSERs in quasilinear time. It is demonstrated that the tree is able to manage the required da ..."
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Cited by 40 (12 self)
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This paper introduces a tracking method for the well known local MSER (Maximally Stable Extremal Region) detector. The component tree is used as an efficient data structure, which allows the calculation of MSERs in quasilinear time. It is demonstrated that the tree is able to manage the required data for tracking. We show that by means of MSER tracking the computational time for the detection of single MSERs can be improved by a factor of 4 to 10. Using a weighted feature vector for data association improves the tracking stability. Furthermore, the component tree enables backward tracking which further improves the robustness. The novel MSER tracking algorithm is evaluated on a variety of scenes. In addition, we demonstrate three different applications, tracking of license plates, faces and fibers in paper, showing in all three scenarios improved speed and stability. 1.
Online learning of unknown hand held objects via tracking
 In Int. Conf. on Computer Vision Systems
, 2006
"... For many computer vision applications labeled/segmented data is needed. Manually assigning labels or segmenting images is a time consuming and tedious task and becomes infeasible for a huge amount of data (e.g., when analyzing a video stream). Thus, this paper proposes a new approach to minimize the ..."
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Cited by 9 (0 self)
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For many computer vision applications labeled/segmented data is needed. Manually assigning labels or segmenting images is a time consuming and tedious task and becomes infeasible for a huge amount of data (e.g., when analyzing a video stream). Thus, this paper proposes a new approach to minimize the manual labeling/segmentation effort for learning an object detector by automatically extracting training data directly from a video sequence. Therefore, a robust background model, a tracker and an online learning method are combined. The main idea is to track an object through a video sequence and to directly use the obtained image patches, showing the object from different views, to incrementally update an existing model which in turn can be used for detection. As the tracker is initialized automatically by change detection, no user interaction is needed! Thus, an unknown object can be learned without having any prior information. To show the benefit of the proposed approach the framework is demonstrated on several typical objects that can be found on a desktop. 1
Ruminations on Tarjan’s unionfind algorithm and connected operators
 in Mathematical Morphology: 40 Years On (Proc. of ISMM). 2005, Computational Imaging and Vision Series
"... Abstract This papers presents a comprehensive and general form of the Tarjan’s unionfind algorithm dedicated to connected operators. An interesting feature of this form is to introduce the notion of separated domains. The properties of this form and its flexibility are discussed and highlighted with ..."
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Cited by 8 (3 self)
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Abstract This papers presents a comprehensive and general form of the Tarjan’s unionfind algorithm dedicated to connected operators. An interesting feature of this form is to introduce the notion of separated domains. The properties of this form and its flexibility are discussed and highlighted with examples. In particular, we give clues to handle correctly the constraint of domaindisjointness preservation and, as a consequence, we show how we can rely on “unionfind ” to obtain algorithms for selfdual filters approaches and levelings with a marker function. Keywords: Unionfind algorithm, reconstructions, algebraic openings and closings, domaindisjointness preservation, selfdual filters, levelings.
3D Segmentation by Maximally Stable Volumes (MSVs)
"... This paper introduces an efficient 3D segmentation concept, which is based on extending the wellknown Maximally Stable Extremal Region (MSER) detector to the third dimension. The extension allows the detection of stable 3D regions, which we call the Maximally Stable Volumes (MSVs). We present a ver ..."
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Cited by 7 (1 self)
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This paper introduces an efficient 3D segmentation concept, which is based on extending the wellknown Maximally Stable Extremal Region (MSER) detector to the third dimension. The extension allows the detection of stable 3D regions, which we call the Maximally Stable Volumes (MSVs). We present a very efficient way to detect the MSVs in quasilinear time by analysis of the component tree. Two applications – 3D segmentation within simulated MR brain images and analysis of the 3D fiber network within digitized paper samples – show that reasonably good segmentation results are achieved with low computational effort. 1.
Detecting, Tracking and Recognizing License Plates
"... Abstract. This paper introduces a novel realtime framework which enables detection, tracking and recognition of license plates from video sequences. An efficient algorithm based on analysis of Maximally Stable Extremal Region (MSER) detection results allows localization of international license pla ..."
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Cited by 6 (2 self)
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Abstract. This paper introduces a novel realtime framework which enables detection, tracking and recognition of license plates from video sequences. An efficient algorithm based on analysis of Maximally Stable Extremal Region (MSER) detection results allows localization of international license plates in single images without the need of any learning scheme. After a onetime detection of a plate it is robustly tracked through the sequence by applying a modified version of the MSER tracking framework which provides accurate localization results and additionally segmentations of the individual characters. Therefore, tracking and character segmentation is handled simultaneously. Finally, support vector machines are used to recognize the characters on the plate. An experimental evaluation shows the high accuracy and efficiency of the detection and tracking algorithm. Furthermore, promising results on a challenging data set are presented and the significant improvement of the recognition rate due to the robust tracking scheme is proved. 1
Ct3d: Tracking Microglia Motility in 3D Using a Novel Cosegmentation Approach
 Bioinformatics
"... Motivation: Cell tracking is an important method to quantitatively analyze timelapse microscopy data. While numerous methods and tools exist for tracking cells in twodimensional (2D) timelapse images, only few and very application specific tracking tools are available for threedimensional (3D) t ..."
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Cited by 6 (0 self)
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Motivation: Cell tracking is an important method to quantitatively analyze timelapse microscopy data. While numerous methods and tools exist for tracking cells in twodimensional (2D) timelapse images, only few and very application specific tracking tools are available for threedimensional (3D) timelapse images, which is of high relevance in immunoimaging, in particular for studying the motility of microglia in vivo. Results: We introduce a novel algorithm for tracking cells in 3D timelapse microscopy data, based on computing cosegmentations between component trees representing individual time frames using socalled treeassignments. For the first time, our method allows to track microglia in three dimensional confocal timelapse microscopy images.We also evaluate our method on synthetically generated data, demonstrating that our algorithm is robust even in the presence of different types of inhomogeneous background noise. Availability: Our algorithm is implemented in the ct3d package, which is available under
Watersheds, mosaics, and the emergence paradigm
, 2005
"... In this paper, we investigate the links between the flooding paradigm and the topological watershed. Guided by the analysis of a classical flooding algorithm, we present several notions that lead us to a better understanding of the watershed: minima extension, mosaic, pass value and separation. We ..."
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Cited by 6 (6 self)
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In this paper, we investigate the links between the flooding paradigm and the topological watershed. Guided by the analysis of a classical flooding algorithm, we present several notions that lead us to a better understanding of the watershed: minima extension, mosaic, pass value and separation. We first make a detailed examination of the effectiveness of the divide set produced by watershed algorithms. We introduce the mosaic to retrieve the altitude of points along the divide set. A desirable property is that, when two minima are separated by a crest in the original image, they are still separated by a crest of the same altitude in the mosaic. Our main result states that this is the case if and only if the mosaic is obtained through a topological thinning. We investigate the possibility for a flooding to produce a topological watershed, and conclude that this is not feasible. This leads us to reverse the flooding paradigm, and to propose a notion of emergence. An emergence process is a transformation based on a topological criterion, in which points are processed in decreasing altitude order while preserving the number of connected components of lower crosssections. Our main result states that any emergence watershed is a topological watershed, and more remarkably, that any topological watershed of a given image can be obtained as an emergence watershed of the image.
Some properties of topological greyscale watersheds
 ROCS. SPIE VISION GEOMETRY XII, FRANCE
, 2004
"... In this paper, we investigate topological watersheds. 1 For that purpose we introduce a notion of “separation between two points ” of an image. One of our main results is a necessary and sufficient condition for a map G to be a watershed of a map F, this condition is based on the notion of separatio ..."
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Cited by 4 (3 self)
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In this paper, we investigate topological watersheds. 1 For that purpose we introduce a notion of “separation between two points ” of an image. One of our main results is a necessary and sufficient condition for a map G to be a watershed of a map F, this condition is based on the notion of separation. A consequence of the theorem is that there exists a (greedy) polynomial time algorithm to decide whether a map G is a watershed of a map F or not. We also show that, given an arbitrary total order on the minima of a map, it is possible to define a notion of “degree of separation of a minimum ” relative to this order. This leads to another necessary and sufficient condition for a map G to be a watershed of a map F. At last we derive, from our framework, a new definition for the dynamics of a minimum.