Perceptual popout is defined by both feature similarity and local feature contrast. We identify these two measures with attraction and repulsion, and unify the dual processes of association by attraction and segregati...
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Perceptual popout is defined by both feature similarity and local feature contrast. We identify these two measures with attraction and repulsion, and unify the dual processes of association by attraction and segregation by repulsion in a single grouping framework. We generalize normalized cuts to multi-way partitioning with these dual measures. We expand graph partitioning approaches to weight matrices with negative entries, and provide a theoretical basis for solution regularization in such algorithms. We show that attraction, repulsion and regularization each contributes in a unique way to popout. Their roles are demonstrated in various salience detection and visual search scenarios. This work opens up the possibilities of encoding negative correlations in constraint satisfaction problems, where solutions by simple and robust eigendecomposition become possible.
Locally parallel dense patterns - sometimes called texture flows - define a perceptually coherent structure which is important to image segmentation, edge classification, shading analysis, and shape interpretation. Th...
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Locally parallel dense patterns - sometimes called texture flows - define a perceptually coherent structure which is important to image segmentation, edge classification, shading analysis, and shape interpretation. This paper develops the notion of texture flow from a geometrical point of view to argue that local measurements of such structures must incorporate two curvatures. We show how basic theoretical considerations lead to a unique model for the local behavior of the flow and allow for the specification of consistency constraints between nearby measurements. The computation of globally coherent structure via neighborhood relationships is demonstrated on synthetic and natural images, and is compared to orientation diffusion.
The National Archives of Singapore keeps a large volume of historical handwritten documents. One common problem with the archives is that over the years, ink sipped through the pages of these documents such that chara...
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The National Archives of Singapore keeps a large volume of historical handwritten documents. One common problem with the archives is that over the years, ink sipped through the pages of these documents such that characters on the reverse side become visible and interfere with the characters on the front side. This paper addresses this problem and develops a novel algorithm to extract clear textual images from the interference. We achieve this by mapping images from both sides of a page such that interfering strokes seen on the front side are matched with the strokes originating from the reverse side so as to achieve a cancellation effect. The resultant image is further subjected to an improved Canny edge detection to eliminate remaining background interference. Experimental results have confirmed the validity of our proposed method.
This paper presents a fast and robust algorithm to identify text in image or video frames with complex backgrounds and compression effects. The algorithm first extracts the candidate text line on the basis of edge ana...
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This paper presents a fast and robust algorithm to identify text in image or video frames with complex backgrounds and compression effects. The algorithm first extracts the candidate text line on the basis of edge analysis, baseline location and heuristic constraints. Support Vector Machine (SVM) is then used to identify text line from the candidates in edge-based distance map feature space. Experiments based on large amount of images and video frames from different sources showed the advantages of this algorithm compared to conventional methods in both identification quality and computation time.
This paper introduces a high-speed parallel system based on DSP to process aerial image. The system is of the master-slave architecture. The master system is composed of general computer. Its slave system based on hig...
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ISBN:
(纸本)0819442836
This paper introduces a high-speed parallel system based on DSP to process aerial image. The system is of the master-slave architecture. The master system is composed of general computer. Its slave system based on high speed DSP TMS320C6201 array can process real time aerial image concurrently. The data communicates between the master system and the slave system through bus interface. In this thesis, on the basis of the fundamental characters of digital imageprocessing. we adopt domain decomposition method suiting digital imageprocessing. The mode can parallelize serial digital image-processing.algorithms which process digital images on spatial domain. This algorithm applies in many image algorithms and can be realized easily. At the same time it ensures every DSP load balance in the course of processing.aerial image. Experiments show the system is effective, simple and steady.
This paper addresses the problem of extracting depth information of non-rigid dynamic 3D scenes from multiple synchronized video streams. Three main issues are discussed in this context: (i) temporally consistent dept...
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This paper addresses the problem of extracting depth information of non-rigid dynamic 3D scenes from multiple synchronized video streams. Three main issues are discussed in this context: (i) temporally consistent depth estimation, (ii) sharp depth discontinuity estimation around object boundaries, and (iii) enforcement of the global visibility constraint. We present a framework in which the scene is modeled as a collection of 3D piecewise planar surface patches induced by color based image segmentation. This representation is continuously estimated using an incremental formulation in which the 3D geometric, motion, and global visibility constraints are enforced over space and time. The proposed algorithm optimizes a cost function that incorporates the spatial color consistency constraint and a smooth scene motion model.
Robustness to changes in illumination conditions as well as viewing perspectives is an important requirement for many computer vision applications. One of the key factors in enhancing the robustness of dynamic scene a...
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Robustness to changes in illumination conditions as well as viewing perspectives is an important requirement for many computer vision applications. One of the key factors in enhancing the robustness of dynamic scene analysis is that of accurate and reliable means for shadow detection. Shadow detection is critical for correct object detection in image sequences. Many algorithms have been proposed in the literature that deal with shadows. However, a comparative evaluation of the existing approaches is still lacking. In this paper, the full range of problems underlying the shadow detection are identified and discussed. We classify the proposed solutions to this problem using a taxonomy of four main classes, called deterministic model and non-model based and statistical parametric and non-parametric. Novel quantitative (detection and discrimination accuracy) and qualitative metrics (scene and object independence, flexibility to shadow situations and robustness to noise) are proposed to evaluate these classes of algorithms on a benchmark suite of indoor and outdoor video sequences.
We outline an Eulerian framework for computing the thickness of tissues between two simply connected boundaries. Thickness is defined as the length of trajectories which follow a smooth vector field constructed in the...
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We outline an Eulerian framework for computing the thickness of tissues between two simply connected boundaries. Thickness is defined as the length of trajectories which follow a smooth vector field constructed in the region between the boundaries. A pair of partial differential equations (PDE's) are then solved and combined to yield length without requiring the explicit construction of the trajectories. An efficient, stable, and computationally fast solution to these PDE's is found by careful selection of finite differences according to an upwinding condition. The behavior and performance of our method is demonstrated on two simulations and two magnetic resonance imaging data sets in two and three dimensions. These experiments reveal very good performance and show strong potential for application in tissue thickness visualization and quantification.
We present a general method of catadioptric sensor design for realizing prescribed projections. Our method makes use of geometric distributions in 3-dimensional space, which are generalizations of vector fields. The m...
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We present a general method of catadioptric sensor design for realizing prescribed projections. Our method makes use of geometric distributions in 3-dimensional space, which are generalizations of vector fields. The main idea is this: if one desires a reflective surface that will image the world in a certain way, then this condition determines the orientation of the tangent planes to the surface. Analytically, this means that the surface will then be determined by a pair of partial differential equations, which may or may not have a common solution. We show how to check if a common solution exists. If no common solution exists, we describe a method for obtaining optimal approximate solutions in a least-squares sense. As an example application, we construct a mirror that will give a panoramic view of a scene without any digital unwarping.
The classical active contour model has two basic internal forces: tension and curvature. These forces are included to provide cohension, equal control point spacing, and locally smooth shape. These classical internal ...
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The classical active contour model has two basic internal forces: tension and curvature. These forces are included to provide cohension, equal control point spacing, and locally smooth shape. These classical internal forces have undesirable attributes that are in conflict with these original desired characteristics. Tension evenly spaces the control points, but also causes the models to collapse in weak image gradients. Curvature produces locally smooth curvature, but it does so by forcing the model toward a straight line. This paper returns to the original active contour model motivations to reformulate these internal forces. The desired properties are achieved without the introduction of unwanted model behavior. A new spacing force and a new constant change in curvature force are introduced and their performance characteristics are discussed. The paper includes experimental results that demonstrate the efficacy and performance of the proposed reformulations.
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