Spatial Filtering for Detection of Signals Submerged in Noise

Kozma, Adam; Kelly, David L.

doi:10.1364/ao.4.000387

Cited by 101 publications

(13 citation statements)

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“…The fundamentals of optical spatial filtering were formulated in that decade, and built upon previous work on optimum linear filtering in communication theory. Achieving the full potential of optical spatial filtering theory requires filters that are complex-valued, and a technique to fabricate such filters was first proposed by VanderLugt [11,15] and others [16], and made practical with alternative arrangements [17]. The techniques allow one to physically encode a complex-valued image on an amplitude-modulating SLM such as photographic film or an LCD panel.…”

Section: Optical Pattern Recognitionmentioning

confidence: 99%

Phase in Optical Image Processing

Naughton¹,

Rastogi²,

Hack³

2010

AIP Conference Proceedings

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Abstract. The use of phase has a long standing history in optical image processing, with early milestones being in the field of pattern recognition, such as VanderLugt's practical construction technique for matched filters, and (implicitly) Goodman's joint Fourier transform correlator. In recent years, the flexibility afforded by phase-only spatial light modulators and digital holography, for example, has enabled many processing techniques based on the explicit encoding and decoding of phase. One application area concerns efficient numerical computations. Pushing phase measurement to its physical limits, designs employing the physical properties of phase have ranged from the sensible to the wonderful, in some cases making computationally easy problems easier to solve and in other cases addressing mathematics' most challenging computationally hard problems. Another application area is optical image encryption, in which, typically, a phase mask modulates the fractional Fourier transformed coefficients of a perturbed input image, and the phase of the inverse transform is then sensed as the encrypted image. The inherent linearity that makes the system so elegant mitigates against its use as an effective encryption technique, but we show how a combination of optical and digital techniques can restore confidence in that security. We conclude with the concept of digital hologram image processing, and applications of same that are uniquely suited to optical implementation, where the processing, recognition, or encryption step operates on full field information, such as that emanating from a coherently illuminated real-world three-dimensional object.

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Section: Optical Pattern Recognitionmentioning

confidence: 99%

Phase in Optical Image Processing

Naughton¹,

Rastogi²,

Hack³

2010

AIP Conference Proceedings

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“…However, it can be shown [31> [33] that the amplitude transmission faetaor can be expanded in series of terms, one of which represent.s exactly the phase of t.he w-ave scattered by the object.. The amplitude information is completely lost.…”

Section: (4)mentioning

confidence: 99%

Microwave holographic interferometry

Papi

Russo

Sottini

1971

IEEE Trans. Antennas Propagat.

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Abstracf-Microwave holography is an extension of the optical holography to the microwave field. In fact, by using a well-known characteristic of the holographic process, it is possible to record the hologram at frequencies very far from the optical region (microwave) and to reconstruct a visible image by laser light. This paper describes the experimental apparatus and the technique used for obtaining a satisfactory optical wave reconstruction from microwave holograms. The resolving power of the system which was experimentally tested, and visible images of microwave transparencies and of a back scattering object are given. As an alternative application of the microwave holography together with the optical wave reconstruction, in this paper, extension of holographic interferometry to the microwave region is suggested, and the visible image of a deformed object crossed by fringes due to microwave interference is also shown. This technique can find applications, for instance, in the mapping of the earth's deformations or in that of the tides. Different aspects of the microwave holographic interferometry have been also discussed.

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“…From another point of view, the reconstruction of realworld images from the phase of their FTs leads to edge enhancement [11][12][13] because elimination of the FT amplitude information stresses the high frequencies. Therefore, the form of the image very often can be detected from the phase of the FT.…”

Section: Introductionmentioning

confidence: 99%

Importance of the phase and amplitude in the fractional Fourier domain

Alieva

Calvo

2003

J. Opt. Soc. Am. A

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The importance of the amplitude and phase in the fractional Fourier transform (FT) domain is analyzed on the basis of the rectangular signal and the real-world image. The quality of signal restoration from only the amplitude or from only the phase of its fractional FT by applying the inverse fractional FT is considered. It is shown that the signal reconstructed from the amplitude of the fractional FT usually reveals the main features of the original signal only for relatively low fractional orders. On the basis of phase information in the fractional FT domains, significant details of the signal can be obtained for nearly all fractional orders.

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Spatial Filtering for Detection of Signals Submerged in Noise

Cited by 101 publications

References 1 publication

Phase in Optical Image Processing

Phase in Optical Image Processing

Microwave holographic interferometry

Importance of the phase and amplitude in the fractional Fourier domain

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