Target location measurement by optical correlators: a performance criterion

Fleisher, Michael; Mahlab, Uri; Shamir, Joseph

doi:10.1364/ao.31.000230

Cited by 14 publications

(3 citation statements)

References 10 publications

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“…Moreover, even if the processing system containing this filter operates as designed, the relation between the position of the correlation peak to the actual position of the object may be not well defined. [36][37][38] Advanced procedures started to deviate from strictly linear methods by supplementing them with optimization processes. These include the minimum average correlation energy filter, 39 the minimum variance filter, 40 and the generalized SF ͑Ref.…”

Section: Correlation Filter Design As An Optimization Problemmentioning

confidence: 99%

Adaptive pattern recognition correlators

Shamir

1997

Opt. Eng

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Optical pattern recognition is significantly improved by exploiting the attributes of both optics and electronics in architectures containing combinations of optical systems and electronic processors. Essential interfaces for such hybrid systems are spatial light modulators and optoelectronic recording devices. These devices suffer from technological limitations that must be alleviated by suitably designed optical architectures and efficient processing algorithms. We review several correlator architectures and discuss their adaptability to hybrid systems. Due to the computational complexity encountered in such hybrid electrooptical systems, iterative optimization methods can be efficiently employed. Some of the algorithms presented are especially useful for treating real physical systems having properties that cannot be exactly defined or quantified. Algorithms that were successful in these architectures belong to two families, the basically stochastic algorithms and the projection-onto-constraint-sets algorithms. The former is particularly suitable for applications in hybrid electro-optical learning systems, while the latter is extremely powerful for the design of spatial filters with properties that are difficult to achieve by other means. A case study is given of an adaptive correlator for rotation-, scale-, and shift-invariant pattern recognition.

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Section: Correlation Filter Design As An Optimization Problemmentioning

confidence: 99%

Adaptive pattern recognition correlators

Shamir

1997

Opt. Eng

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“…We call those marks synthetic references ͑SRs͒. 9 Detection reliability, however, does not depend only on noise. 1,2 SRs are commonly designed as binary targets of finite extent.…”

Section: Introductionmentioning

confidence: 99%

Detection of small-size synthetic references in scenes acquired with a pixelated device

Fernández¹,

Amat

1997

Opt. Eng

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A synthetic reference (SR) or fiducial mark is a target that has been designed and placed within a scene in order to help to locate objects. When a scene containing a small SR is acquired through a pixelated device (such as a CCD camera) and this SR is located using a digitally computed normalized correlation search, there is a lowering of the correlation peak if the target SR is displaced a nonwhole number of pixels with respect to the position of the previously acquired model SR. We propose a framework where the lowering is related to detection reliability, in order to compare the performance of different sizes and shapes of SR. This framework has been applied to eight SRs having simple shapes, using synthetic scenes. Results show large differences in their detection reliability according to their shape. A SR in the shape of a 45-deg-tilted square shows the best behavior among all the studied shapes, and one can take advantage of this fact when designing an application dealing with small-size SRs. © 1997 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(97)02211-3]

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“…Examples of these requirements are rotation invariance, scale invariance, and tilt invariance. Various dedicated procedures were proposed in the past, such as circular harmonic component 1 1CHC2 filters and CHC phaseonly filters 2 1CHC POF's2 for rotation-invariant PR, the Fourier-Mellin transform 3 for scale-invariant PR, position determination, 4 etc. The underlying characteristic of the above approaches is that they assume, a priori, a predefined structure for the filter.…”

Section: Introductionmentioning

confidence: 99%

Application of serial- and parallel-projection methods to correlation-filter design

1995

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We describe generalized projection procedures for the design of arbitrary filter functions for correlators. More specifically, serial and parallel implementations of projection-based algorithms are employed. The novelty of this procedure lies in its generality and its ability to handle wide varieties of constraints by the same procedure. The procedure is demonstrated by the design of filters for the 4-f linear correlator, the phase-extraction correlator, and variants thereof. The filters are subject to a variety of constraints, including rotation-invariant pattern recognition and class discrimination. Examples are given to show the versatility, flexibility, and applicability of the design process to a variety of pattern-recognition tasks. Satisfactory results are also obtained because of the combination with the special nonlinear correlators proposed for pattern recognition.

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Target location measurement by optical correlators: a performance criterion

Cited by 14 publications

References 10 publications

Adaptive pattern recognition correlators

Adaptive pattern recognition correlators

Detection of small-size synthetic references in scenes acquired with a pixelated device

Application of serial- and parallel-projection methods to correlation-filter design

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