Segmentation using boundary finding is enhanced both by considering the boundary as a whole and by using model-based shape information. Flexible constraints, in the form of a probabilistic deformable model, are applie...
详细信息
ISBN:
(纸本)081861952x
Segmentation using boundary finding is enhanced both by considering the boundary as a whole and by using model-based shape information. Flexible constraints, in the form of a probabilistic deformable model, are applied to the problem of segmenting natural objects whose diversity and irregularity of shape makes them poorly represented in terms of fixed features of forms. The parametric model is based on the elliptic Fourier decomposition of the boundary. The segmentation problem is solved as an optimization problem, where the best match between the boundary (as defined by the parameter vector) and the image data is found. Initial experimentation shows good results on a variety of images.
A technique for the estimation of 2-D normal velocity is presented. The image sequence is first represented by a family of velocity-tuned linear filters. Normal velocity, in the individual filter outputs, is expressed...
详细信息
ISBN:
(纸本)081861952x
A technique for the estimation of 2-D normal velocity is presented. The image sequence is first represented by a family of velocity-tuned linear filters. Normal velocity, in the individual filter outputs, is expressed as the local first-order behavior of surfaces of constant phase. Justification for this is discussed, and it is shown to provide an effective basis for the local computation of normal velocity. The resultant approach is local in space-time. It permits multiple velocity estimates within a single neighborhood, and it yields accurate velocity estimates that are robust with respect to noise and perspective deformation.
A method for detecting and describing the features of faces using deformable templates is described. The feature of interest, an eye for example, is described by a parameterized template. An energy function is defined...
详细信息
ISBN:
(纸本)081861952x
A method for detecting and describing the features of faces using deformable templates is described. The feature of interest, an eye for example, is described by a parameterized template. An energy function is defined which links edges, peaks, and valleys in the image intensity to corresponding properties of the template. The template then interacts dynamically with the image, by altering its parameter values to minimize the energy function, thereby deforming itself to find the best fit. The final parameter values can be used as descriptors for the features. This method is demonstrated by showing deformable templates detecting eyes and mouths in real images.
The use of Markov random fields (MRFs) in color image segmentation of natural outdoor scenes is discussed. MRFs provide an elegant means of specifying a local energy function which embodies the expected dependencies o...
详细信息
ISBN:
(纸本)081861952x
The use of Markov random fields (MRFs) in color image segmentation of natural outdoor scenes is discussed. MRFs provide an elegant means of specifying a local energy function which embodies the expected dependencies of neighboring pixels and includes both the prior and posterior probabilistic distributions. This local neighborhood-based specification of dependencies avoids ad hoc brittle methods using global image knowledge. A brief analysis of ongoing research in color differencing methods is presented, since they are central to the problem of color segmentation. The authors develop and compare the use of three different lattice structures for coupled MRFs with line and color processes based on squares, hexagons, and triangles, and also discusses current efforts in MRF parameter understanding.
One of the classic results of mathematical morphology is the filter-representation theorem of G. Matheron (1975) for black-and-white images. The theorem states that any morphological filter can be represented as a uni...
详细信息
ISBN:
(纸本)081861952x
One of the classic results of mathematical morphology is the filter-representation theorem of G. Matheron (1975) for black-and-white images. The theorem states that any morphological filter can be represented as a union of erosions by elements in the filter's kernel. In its dual form, it states that the erosion representation can be replaced by an intersection of dilations by elements of the dual filter's kernel. Here, the dual-form of the gray-scale representation is derived in terms of a minimum of dilations by elements in the dual filter's kernel.
The grid-labeling problem is an instance of the correspondence problem that occurs when structured light is used to gather range data. Here, spatial labeling is examined as an approach to resolving labeling ambiguitie...
详细信息
ISBN:
(纸本)081861952x
The grid-labeling problem is an instance of the correspondence problem that occurs when structured light is used to gather range data. Here, spatial labeling is examined as an approach to resolving labeling ambiguities. Spatial labeling is attractive since there are no additional costs of acquisition time or subsequent processing.time. A grid labeling algorithm is presented which combines the spatial marking technique of J. LeMigne and A.M. Waxman (1984) with the constraint propagation approach of G. Stockman and G. Hu (1986). It is found accurate grid labeling using the market grid can be accomplished using a subset of Stockman and Hu's constraints. The structured light pattern used and the grid labeling algorithm that makes use of the special markers are described. The results of experiments using this pattern are presented.
Conventional approaches to dynamic scene analysis do not use motion itself explicitly for recognition. The authors propose a different approach for the use of motion in a computer vision system which uses the motion c...
详细信息
ISBN:
(纸本)081861952x
Conventional approaches to dynamic scene analysis do not use motion itself explicitly for recognition. The authors propose a different approach for the use of motion in a computer vision system which uses the motion characteristics of moving objects without actually recovering the structure. In this approach, the extended trajectories followed by the objects are considered. It is argued that in many cases, where an object has a fixed and predefined motion, the trajectory of several points may serve to uniquely identify the object. In this approach, the trajectories are analyzed at multiple scales to identify important events corresponding to discontinuities in direction, speed, and acceleration using scale space. These important events are recorded in a presentation called trajectory primal sketch. Experimental results are presented graphically, demonstrating the potential value of this approach.
A novel algorithm for three-dimensional edge detection is proposed. This method is an extension to the 3-D case of the optimal 2-D edge detector recently introduced by R. Deriche (1987). The authors present better the...
详细信息
ISBN:
(纸本)081861952x
A novel algorithm for three-dimensional edge detection is proposed. This method is an extension to the 3-D case of the optimal 2-D edge detector recently introduced by R. Deriche (1987). The authors present better theoretical and experimental performances than some classical approaches used previously. Experimental results obtained on magnetic-resonance images and on echographic images are shown. It is pointed out that this approach can be used to detect edges in other multidimensional data, for instance, 2D + t or 3D + t images.
Edge detection is analyzed as a problem in cost minimization. A cost function is formulated that evaluates the quality of edge configurations. A mathematical description of edges is given, and the cost function is ana...
详细信息
ISBN:
(纸本)081861952x
Edge detection is analyzed as a problem in cost minimization. A cost function is formulated that evaluates the quality of edge configurations. A mathematical description of edges is given, and the cost function is analyzed in terms of the characteristics of the edges in minimum-cost configurations. The cost function is minimized by the simulated annealing method. A novel set of strategies for generating candidate states and a suitable temperature schedule are presented. Sequential and parallel versions of the annealing algorithm are implemented and compared. Experimental results are presented.
A robust edge-detection algorithm which performs equally under a wide variety of noisy situations and a broad range of edges is described. The algorithm is executed in three phases. In phase 1, the step and linear edg...
详细信息
ISBN:
(纸本)081861952x
A robust edge-detection algorithm which performs equally under a wide variety of noisy situations and a broad range of edges is described. The algorithm is executed in three phases. In phase 1, the step and linear edges are detected from the noise-corrupted image using a statistical classification technique. In phase 2, all the thin-line edges (i.e., which are lines less than two pixels wide) are detected by a supplementary technique since these edges cannot be detected simultaneously with the other step and linear edges. In phase 3, the spurious edge elements are suppressed and the isolated missing edge elements are interpolated using a number of hypothesized edge-segments. Finally some experimental results are provided to illustrate the success of the algorithm.
暂无评论