In this paper we consider a new form of connectivity in binary images, called k -width connectivity. Two pixels a and b of value “1” are in the same k -width component if and only if there exists a path of width k s...
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In this paper we consider a new form of connectivity in binary images, called k -width connectivity. Two pixels a and b of value “1” are in the same k -width component if and only if there exists a path of width k such that a is one of the k start pixels and b is one of the k end pixels of this path. We present characterizations of the k -width components and show how to determine the k -width components of an n × n image in O(n) and O (log 2 n ) time on a mesh of processors and hypercube, respectively, when the image is stored with one pixel per processor. Our methods use a reduction of the k -width-connectivity problem to the 1-width-connectivity problem. A distributed, space-efficient encoding of the k -width components of small size allows us to represent the solution using O (1) registers per processor. Our hypercube algorithm also implies an algorithm for the shuffle-exchange network.
A mixed-mode parallel machine's processing elements (PEs) are capable of operating in and switching between the SIMD and MIMD modes of parallelism. The paper analyzes various mappings of image correlation algorith...
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A mixed-mode parallel machine's processing elements (PEs) are capable of operating in and switching between the SIMD and MIMD modes of parallelism. The paper analyzes various mappings of image correlation algorithms onto a mixed-mode parallelprocessing system. The trade-offs that exist between the SIMD and MIMD modes explain why some sequences of instructions are performed better in one mode than in the other and are the primary basis employed in comparing different mappings of a parallel algorithm onto a mixed-mode system.< >
The binary de Bruijn graph (BDG) is a realizable alternative to the hypercube. An extension of the BDG by the edge set union with a torus is shown-union-graph (UG). This achieves graph capabilities/versatility compara...
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The binary de Bruijn graph (BDG) is a realizable alternative to the hypercube. An extension of the BDG by the edge set union with a torus is shown-union-graph (UG). This achieves graph capabilities/versatility comparable to the product shuffle (PS) graph and the hypercube within a fixed degree graph. The UG improves upon both in implementing pipelined and multi-phase algorithms. More importantly, the purpose being to design an algorithmically specialized interconnect, with the algorithmic features of a wide range of algorithms as well as direct architectural support for them, instead of simple providing for a set of graph embeddings in the interconnect. A set of examples demonstrate the UG's versatility in this aspect of algorithmic support.< >
A neural controller for visually guided navigation of a mobile robot in the presence of dynamic obstacles and a vector field of attraction forces is presented. Discrete information, obtained from a raster-type sensor,...
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A neural controller for visually guided navigation of a mobile robot in the presence of dynamic obstacles and a vector field of attraction forces is presented. Discrete information, obtained from a raster-type sensor, is subjected to paralleldistributedprocessing aiming at real-time detection of geometrical properties of visual representations of the obstacles. A characteristic feature of the neural architecture adopted here is processing of the input data by a hidden layer of dipole units. This novel approach allows the controller to perform the operations of edge detection and recognition of geometrical features within the controller’s structure rather than using visual data pre-processed by classical convolution-based methods. Dipole processing combined with the ability of our network to learn arbitrary associations very rapidly by self-programming permits the processing of large amounts of input data without compromising the efficiency of the learning phase. The capability of the network to extract and process some geometrical characteristics of the environment works for both local (limited by a field of view window) and global navigation. The behavior of the robot in the vicinity of obstacles can be tuned and modified by changing the number of recursively generated obstacle hulls, the size of the window, and the weights of the force components intervening in the control.
A paralleldistributedprocessing method for extracting features in stereo images is presented. The algorithm is edge-based and employs the epipolar constraint. First edges are detected in a multilayered network using...
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In this paper we consider a new form of connectivity in binary images, called k-width-connectivity. Two pixels a and 6 of value are in the same k-width- component if and only if there exists a path of width k such tha...
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A paralleldistributedprocessing method for extracting features in stereo images is presented. The algorithm is edge-based and employs the epipolar constraint. First edges are detected in a multilayered network using...
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A paralleldistributedprocessing method for extracting features in stereo images is presented. The algorithm is edge-based and employs the epipolar constraint. First edges are detected in a multilayered network using two methods of locating the magnitude of directional first derivatives and the zero-crossing of second derivatives of smoothed images. The combined edge detection process helps to eliminate 'phantom' edges. Then features that are likely to be detectable in both images are selected. These features are edge intervals and edge orientation, that is, the intersection of image edges with the epipolar line and the corresponding slope of the edges at those points. The feature extraction process is implemented in a two-layered paralleldistributedprocessing model. The first layer provides edge interval representations. The second layer computes a similarity of measure for each pair of primitive matches which are then forwarded to the second stage of the algorithm. The purpose of the second stage is to turn the difficult pixel correspondence problem into a constraint satisfaction problem by imposing relational constraints. This constraint satisfaction is then solved using a neural network. The results of computer simulations are presented to demonstrate the effectiveness of the approach.< >
The authors consider a new form of connectivity in binary images, called k-width-connectivity. Two pixels a and b of value '1' are in the same k-width-component if and only if there exists a path of width k su...
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The authors consider a new form of connectivity in binary images, called k-width-connectivity. Two pixels a and b of value '1' are in the same k-width-component if and only if there exists a path of width k such that a is one of the k start pixels and b is one of the k end pixels of this path. The authors present characterisations of the k-width-components and show how to determine the k-width-components of an n*n image in O(n) and O(log/sup 2/ n) time on a mesh of processors and hypercube, respectively, when the image is stored with one pixel per processor. The methods use a reduction of the k-width-connectivity problem to the 1-width-connectivity problem. A distributed, space-efficient encoding of the k-width-components of small size allows the solution to be represented using O(l) registers per processor. The hypercube algorithm also implies an algorithm for the shuffle-exchange network.< >
An image algebra has been defined which is capable of expressing a wide variety of gray-level image-to-image transformations. The purpose of this paper is fourfold: (1) to introduce the reader to the basic concepts of...
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An image algebra has been defined which is capable of expressing a wide variety of gray-level image-to-image transformations. The purpose of this paper is fourfold: (1) to introduce the reader to the basic concepts of the image algebra; (2) to show how it suggests a general-purpose cellular pyramid array processor for real time imageprocessing tasks; (3) to demonstrate how the image algebra can be used to formulate the problem of mapping algorithms to specific hardware; and (4) to show how algebraic techniques can be used to develop systematic methods for deriving parallel algorithms.
A high-performance systolic machine, called Warp, is operational at Carnegie Mellon. The machine has a programmable systolic array of linearly connected cells, each capable of performing 10 million floating-point oper...
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A high-performance systolic machine, called Warp, is operational at Carnegie Mellon. The machine has a programmable systolic array of linearly connected cells, each capable of performing 10 million floating-point operations per second. Many imageprocessing operations have been programmed on the machine. This programming experience has yielded new insights in the mapping of imageprocessing operations onto a parallel computer. This paper identifies three major mapping methods that are particularly suited to a Warp-like parallel machine using a linear array of processing elements. These mapping methods correspond to partitioning of input dataset, partitioning of output dataset, and partitioning of computation along the time domain (pipelining). parallel implementations of several important imageprocessing operations are presented to illustrate the mapping methods. These operations include the Fast Fourier transform (FFT), connected component labelling, Hough transform image warping and relaxation.
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