In this paper non-Bayesian and heuristic approaches are applied to the well known problem of image segmentation. The two subproblems in segmentation that were considered were region merge and line detection. For the region merge problem, a comparison was made between the classical Bayes and fuzzy set based approach. Simulations, using a "block world" type real image, were implemented in ZETALISP on the Symbolics 3675 computer. They contrasted the proposed region merge method with the classical implementations. The performance measures of the classical line detection problem, using the Hough transform, are reinterpreted in a non-traditional framework using fuzzy sets and heuristics. Several alternative real-time optical Hough transform schemes are presented as well.
A new optical Fourier domain filtering scheme that combines the conventional optical space-invariant linear filtering with a self-pumped nonlinear-optical phase-conjugation technique is proposed. The new method is used for a real-time detection and channel evaluation of the multipath information needed in radar, sonar, and communication signal-processing applications. Preliminary experimental demonstrations are included.
Optical phase conjugate devices utilize a variety of physical phenomena to exactly reverse the direction of propagation of an incident optical beam.. A recent survey of some of the possible optical devices is available 1 . The interest in using these devices for optical logic, computation and interconnect stems from the ultrafast, subpicosecond, switching speed that optical four wave mixing (FWM) devices are able to achieve 2 . For all optical logic network both the input and the output logic variables must be optical quantities. Four-wave mixing elements, because they require a number of optical beams for its operation, are candidates for such networks. Optical FWM logic assignments use various polarization and amplitude coding schemes to realize canonical logic, such as an AND and an OR, gate configurations 3-5 .
There are many pattern recognition problems where the pattern's structural information is important. In these problems, a syntactic method of pattern recognition is of value. In this paper, both parallel syntactic pattern recognition algorithm and optical architecture implementation approaches are described. In particular, the applications of syntactic pattern recognition algorithm to shape classification are illustrated. A number of parallel optical syntactic pattern coding methods, a structural matched filter and associative memory filter, and an optical symbolic substitution syntactic parser are discussed.
The Hough transform (HT) is an efficient shape detector that maps straight lines into a two-parameter feature space. Recently it has been pointed out that the forward Radon transform (FRT), well known from the theory of computed tomography, and the HT are equivalent for binary images. In this paper, analog coherent optical implementation of the FRT is discussed. The FRT will not only be of use in implementing the HT shape descriptors but also act as a coherent optical preprocessor for the implementation of multidimensional convolution, correlation, and spectral analysis using 1-D acoustooptical signal processing devices. Several different coherent optical FRT architectures are presented. Experimental results using conventional coherent Fourier transform configuration are given. The relationship between the coherent optical implementation of the FRT and the inverse Radon transform, an important tool in computed tomography, is also detailed.
Abstract : This report discusses the following subjects: (1) A new technique to achieve a fast PN Acquisition scheme; (2) A comparison of schemes for coarse acquisition of frequency-hopped spread-spectrum signals; (3) Investigation of the tracking of frequency hopped spread spectrum signals in adverse environments; (4) Coherent optical production of the Hough transform; (5) Estimation of the closely spaced frequencies buried in white noise using linear programming; (6) Restoration of discrete Fourier spectra using linear programming; (7) Two-dimensional optical filtering of 1-D signals; (8) Random TDMA Access Protocol with application to multi beam satellites; and (9) A reservations scheme of multiple access for local networks.
The use of optical phase conjugation (OPC) process for parallel digital and symbolic optical computing is described. Using spatially encoded logic and sym-bolic variables, various OPC-based parallel ultrafast optical logic, symbolic as well as interconnect processors are detailed. The proposed devices are experimen-tally verified using picosecond pulses from a mode-locked Nd3+:YAG laser. Based on these processors, an OPC-based ultrafast optical computing architecture is proposed.
A conventional binary multiplication scheme, after forming an array of partial products, uses a series of ripple carry additions. To increase a multiplication speed, an optical digital multiplication through an analog convolution (DMAC) algorithm was proposed. However, because of the inherent analog processing disadvantages and lack of a large dynamic range A-D converter for the proposed optical DMAC scheme, it is difficult to compete with a fast electronic multiplication scheme. In this paper a new approach is proposed to modify a standard optical DMAC scheme. Instead of using an A-D converter and an array of ripple carry adders, an array of multiple input binary symmetric logic modules (BSLM) is employed for the generation of a set of fast multiple digit binary additions. Fundamental properties of a BSLM and its key role in the proposed optical fast multiplication scheme are addressed.
The modified signed digit (MSD) number system offers inherent low interdigit dependence for arithmetic processing. Recently, using both optical logic and memory based approaches, various optical MSD arithmetic schemes were proposed. For the logic based optical MSD arithmetic, an existing approach implements a three-stage processing algorithm with either a symbolic substitution processor or some binary logic elements, such as bistable etalons. Because of the use of multiple processing stages, the required computing energy and its speed is sacrificed. The optical memory based approach, on the other hand, utilizes a single-stage content addressable memory (CAM) for a fast MSD arithmetic. However, the existing holographic CAM is difficult to implement. In this talk, a new nonholographic CAM scheme for a single-stage MSD addition processing is proposed and demonstrated. A position encoded 18 × 56 pixel CAM mask is used in an angularly multiplexed geometry for a parallel CAM matching operation. Electronic logic inverters are used as the output devices.
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