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Combinatorial graph cut algorithms have been successfully applied to a wide range of problems in computer vision and graphics. In this paper we have analyzed mainly four techniques Graph cuts (GC), Iterative Graph Cuts (IGC), Multi-label Random walker (RW) and Lazy Snapping (LS). Graph Cut techniques are used for completely automatic high-level grouping of image pixels. Iterative Graph Cut technique allows some sort of user interaction for extracting objects from a complex background. Random Walker algorithm requires user specific labels and produce a segmentation where each segment is connected to a labeled pixel. Lazy Snapping provides instant visual feedback, snapping the cutout contour to the true object boundary efficiently despite the presence of ambiguous or low contrast edges.
An image can be considered as a group of nodes as vertices and edges as links. Various techniques are formed based upon this assumption and energy minimization. Graph cut is one of the promising techniques for image segmentation. Boykov and Kolmogorov use mincut/ maxflow graph principal for image segmentation. We have discussed some other techniques such as grab cut which is user interactive and very effective technique. In last the current problems were also highlighted.
Procedia Engineering, 2012
This paper introduces a new interactive image segmentation algorithm. This algorithm gets better result with fewer users interactive when segmenting single-object from images with complex foreground and background. Experiments show that this algorithm effectively solve the common over-segmentation and less-segmentation in graph cut, as well as resolve the problem of small regions error segmented in grab cut algorithm.
Procedings of the British Machine Vision Conference 2008, 2008
The graph cut based approach has become very popular for interactive segmentation of the object of interest from the background. One of the most important and yet largely unsolved issues in the graph cut segmentation framework is parameter selection. Parameters are usually fixed beforehand by the developer of the algorithm. There is no single setting of parameters, however, that will result in the best possible segmentation for any general image. Usually each image has its own optimal set of parameters. If segmentation of an image is not as desired under the current setting of parameters, the user can always perform more interaction until the desired results are achieved. However, significant interaction may be required if parameter settings are far from optimal. In this paper, we develop an algorithm for automatic parameter selection. We design a measure of segmentation quality based on different features of segmentation that are combined using AdaBoost. Then we run the graph cut segmentation algorithm for different parameter values and choose the segmentation of highest quality according to our learnt measure. We develop a new way to normalize feature weights for the AdaBoost based classifier which is particularly suitable for our framework. Experimental results show a success rate of 95.6% for parameter selection.
2007
In this work, we present a common framework for seeded image segmentation algorithms that yields two of the leading methods as special cases -The Graph Cuts and the Random Walker algorithms. The formulation of this common framework naturally suggests a new, third, algorithm that we develop here. Specifically, the former algorithms may be shown to minimize a certain energy with respect to either an ℓ 1 or an ℓ 2 norm. Here, we explore the segmentation algorithm defined by an ℓ ∞ norm, provide a method for the optimization and show that the resulting algorithm produces an accurate segmentation that demonstrates greater stability with respect to the number of seeds employed than either the Graph Cuts or Random Walker methods.
2008 Ieee 16th Signal Processing Communication and Applications Conference, 2008
A graph theoretic color image segmentation algorithm is proposed, in which the popular normalized cuts image segmentation method is improved with modifications on its graph structure. The image is represented by a weighted undirected graph, whose nodes correspond to over-segmented regions, instead of pixels, that decreases the complexity of the overall algorithm. In addition, the link weights between the nodes are calculated through the intensity similarities of the neighboring regions. The irregular distribution of the nodes, as a result of such a modification, causes a bias towards combining regions with high number of links. This bias is removed by limiting the number of links for each node. Finally, segmentation is achieved by bipartitioning the graph recursively according to the minimization of the normalized cut measure. The simulation results indicate that the proposed segmentation scheme performs quite faster than the traditional normalized cut methods, as well as yielding better segmentation results due to its regionbased representation.
2008
Graph cut is a popular technique for interactive image segmentation. However, it has certain shortcomings. In particular, graph cut has problems with segmenting thin elongated objects due to the "shrinking bias". To overcome this problem, we propose to impose an additional connectivity prior, which is a very natural assumption about objects. We formulate several versions of the connectivity constraint and show that the corresponding optimization problems are all NP-hard.
Image segmentation is the process of subdividing a digital image into its systematized regions or objects which is useful in image analysis. In this review paper, we carried out an organized survey of many image segmentation techniques which are flexible, cost effective and computationally more efficient. We classify these segmentation methods into three categories: the traditional methods, graph theoretical methods and combination of both traditional and graph theoretical methods. In the second and third category of image segmentation approaches, the image is modeled as a weighted and undirected graph. Normally a pixel or a group of pixels are connected with nodes. The edge weights represent the dissimilarity between the neighborhood pixels. The graph or the image is then divided according to a benchmark designed to model good clusters. Every partition of the nodes or the pixels as output from these algorithms is measured as an object segment in an image representing a graph. Some of the popular algorithms are thresholding, normalized cuts, iterated graph cut, clustering method, watershed transformation, minimum cut, grey graph cut, and minimum spanning treebased segmentation.
Image Processing, 2005. ICIP 2005. …, 2005
Fundamental to any graph cut segmentation methods is the assignment of edge weights. The existing solutions typically use gaussian, exponential or rectangular cost functions with a parameter chosen in an ad-hoc fashion. We demonstrate the importance of the shape of the cost function in images of convoluted shaped objects. Our asymptotical analysis and empirical results show that the gaussian cost function outperforms the rectangular and exponential cost functions. For the gaussian cost function we construct a theoretical framework to determine the optimal value of its parameter based on the image data and shape complexity.
IEEE Transactions on Systems, Man, and Cybernetics - Part A: Systems and Humans, 2008
A novel thresholding algorithm is presented in this paper to improve image segmentation performance at a low computational cost. The proposed algorithm uses a normalized graphcut measure as thresholding principle to distinguish an object from the background. The weight matrices used in evaluating the graph cuts are based on the gray levels of the image, rather than the commonly used image pixels. For most images, the number of gray levels is much smaller than the number of pixels. Therefore, the proposed algorithm requires much smaller storage space and lower computational complexity than other image segmentation algorithms based on graph cuts. This fact makes the proposed algorithm attractive in various real-time vision applications such as automatic target recognition. Several examples are presented, assessing the superior performance of the proposed thresholding algorithm compared with the existing ones. Numerical results also show that the normalized-cut measure is a better thresholding principle compared with other graph-cut measures, such as average-cut and average-association ones.
Lecture Notes in Computer Science, 2011
Graph cut algorithms are very popular in image segmentation approaches. However, the detailed parts of the foreground are not segmented well in graph cut minimization.There are basically two reasons of inadequate segmentations: (i) Data-smoothness relationship of graph energy. (ii) Shrinking bias which is the bias towards shorter paths. This paper improves the foreground segmentation by integrating the statistical significance measure into the graph energy minimization. Significance measure changes the relative importance of graph edge weights for each pixel. Especially at the boundary parts, the data weights take more significance than the smoothness weights. Since the energy minimization approach takes into account the significance measure, the minimization algorithm produces better segmentations at the boundary regions. Experimental results show that the statistical significance measure makes the graph cut algorithm less prone to bias towards shorter paths and better at boundary segmentation.
2012
The graph partitioning has been widely used as a mean of image segmentation. One way to partition graphs is through a technique known as Normalized Cut, which analyzes the graph’s Laplacian matrix eigenvectors and uses some of them for the cut. This work proposes the use of Normalized Cut in graphs generated by structures based on Quadtree and Component Tree to perform image segmentation. Experiments of image segmentation by Normalized Cut in these models are made and a specific benchmark compares and ranks the results obtained by other graph-conversion techniques proposed in the literature. The results are promising and allow us to conclude that the use of different graph models combined with the Normalized Cut can yield better segmentations according to the characteristics of images. Keywords-Image Segmentation; Normalized Cut; Quadtree; Component Tree
2012
ABSTRACT We present a general graph-cut segmentation framework GGC, in which the delineated objects returned by the algorithms optimize the energy functions associated with the lp norm, 1≤ p≤∞. Two classes of well known algorithms belong to GGC: the standard graph cut GC (such as the min-cut/max-flow algorithm) and the relative fuzzy connectedness algorithms RFC (including iterative RFC, IRFC).
Image segmentation plays a crucial role in effective understanding of digital images. Past few decades saw hundreds of research contributions in this field. However, the research on the existence of general purpose segmentation algorithm that suits for variety of applications is still very much active. Among the many approaches in performing image segmentation, graph based approach is gaining popularity primarily due to its ability in reflecting global image properties. This paper critically reviews existing important graph based segmentation methods. The review is done based on the classification of various segmentation algorithms within the framework of graph based approaches. The major four categorizations we have employed for the purpose of review are: graph cut based methods, interactive methods, minimum spanning tree based methods and pyramid based methods. This review not only reveals the pros in each method and category but also explores its limitations. In addition, the review highlights the need for creating a database for benchmarking intensity based algorithms, and the need for further research in graph based segmentation for automated real time applications.
Jurnal Teknologi, 2015
Graph cut is an interactive segmentation method. It works based on preparing graph from image and finds the minimum cut for the graph. The edges value is calculated based on belonging a pixel to object or background. The advantage of this method is using the cost function. If the cost function is clearly described, graph cut is presents a generally optimum result. In this paper graph concepts and preparing graph according to image pixels is described. Preparing different edges and performing min cut/max flow is explained. Finally, the method is applied on some medical images.
2006
Abstract. Image segmentation using graph cuts have become very popular in the last years. These methods are computationally expensive, even with hard constraints (seed pixels). We present a solution that runs in time proportional to the number of pixels. Our method computes an ordered region growing from a set of seeds inside the object, where the propagation order of each pixel is proportional to the cost of an optimum path in the image graph from the seed set to that pixel.
International Journal for Research in Applied Science and Engineering Technology
In image processing, segmentation is the process of partitioning digital image into multiple sets of pixels, according to some homogeneity standard. The goal of segmentation is to simplify or change the representation of an image into something that is more meaningful and easier to analyze. Segmentation by computing a minimal cut in a graph is a new and quite general approach for segmenting images. This approach guarantees global solutions, which always find best solution. Graph cut has emerged as a preferred method to solve a class of energy minimization problems such as Image Segmentation. In this paper we used graph cut method to solve image segmentation problem and we got successful results in image segmentation. In this project we proposed a new approach by using optimized normalized cut with combination with K-means algorithm to do the segmentation of static image. In this method we used efficient computational technique based on eigen values and eigen vectors to get optimized segmented image.
Abstract The analysis of digital scenes often requires the segmentation of connected components, named objects, in images and videos. The problem consists of defining the whereabouts of a desired object (recognition) and its spatial extension in the image (delineation). Humans can outperform computers in recognition, but the other way around is valid for delineation.
Lecture Notes in Computer Science, 2008
We present a novel graph-based approach to image segmentation. The objective is to partition images such that nearby pixels with similar colors or grayscale intensities belong to the same segment. A graph representing an image is derived from the similarity between the pixels and partitioned by a computationally efficient graph clustering method, which identifies representative nodes for each cluster and then expands them to obtain complete clusters of the graph. Experiments with synthetic and natural images are presented. A comparison with the well known graph clustering method of normalized cuts shows that our approach is faster and produces segmentations that are in better agreement with visual assessment on original images.
Lecture Notes in Computer Science, 2008
This study investigates a variational multiphase image segmentation method which combines the advantages of graph cut discrete optimization and multiphase piecewise constant image representation. The continuous region parameters serve both image representation and graph cut labeling. The algorithm iterates two consecutive steps: an original closed-form update of the region parameters and partition update by graph cut labeling using the region parameters. The number of regions/labels can decrease from an initial value, thereby relaxing the assumption that the number of regions is known beforehand. The advantages of the method over others are shown in several comparative experiments using synthetic and real images of intensity and motion.
Procedings of the British Machine Vision Conference 2010, 2010
In this paper, we present a graph-based image segmentation method (patch-cuts) that incorporates features and spatial relations obtained from image patches. In the first step, patch-cuts extracts a set of patches that can assume arbitrary shape and size. Patches are determined by a combination of intensity quantization and morphological operations and render the proposed method robust against noise. Upon patch extraction, a set of intensity, texture and shape features are computed for each patch. These features are integrated and minimized simultaneously in a tunable energy function. Patch-cuts explores the benefit of information theory-based measures such as the Kullback-Leibler and the Jensen-Shannon divergence in its energy terms. In our experiments, we applied patchcuts to general images as well as to non-contrast Computed Tomography heart scans.
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