&lt;title&gt;Complex characterization of the Epson liquid crystal television&lt;/title&gt;

Soutar, Colin; Monroe, Stanley E.; Knopp, Jerome

doi:10.1117/12.160293

Cited by 11 publications

(6 citation statements)

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“…In this case the method is similar to the methods proposed in [14] and [15] to characterize a SLM. However, it may happen that these conditions could not be obtained with the S L M used to display the image in the correlator.…”

Section: In-situ Characterization Of the Filter Spatial Light Modulatormentioning

confidence: 83%

Fullin-situcharacterization of spatial light modulators in an optical correlator. Filter adaptation to operating curves

López‐Coronado

Moreno

Campos

et al. 1998

Journal of Modern Optics

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In this paper we present one method for the characterization of the spatial light modulators (SLMs) of a real-time Vander Lugt type of correlator. This correlator uses two SLMs: one to introduce the scene and a second to introduce the frequency-matched filter. T h e S L M characterization methods are in situ, that is in the correlator set-up. Illumination conditions are different for each SLM, and consequently different characterization techniques must be used in each case. For the characterization of the scene S L M a diffraction method is used, while for the characterization of the filter S L M an interferometric technique is more convenient. Finally, we take into account the operating curves of scene and filter SLMs in the design of the filter in order to optimize the correlation peak.

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Section: In-situ Characterization Of the Filter Spatial Light Modulatormentioning

confidence: 83%

Fullin-situcharacterization of spatial light modulators in an optical correlator. Filter adaptation to operating curves

López‐Coronado

Moreno

Campos

et al. 1998

Journal of Modern Optics

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“…12 for an overview of the photorefractive effect and its applications). 12 for an overview of the photorefractive effect and its applications).…”

Section: Experimental Methodsmentioning

confidence: 99%

<title>Joint transform correlator using photorefractie Bi<formula><inf><roman>12</roman></inf></formula>SiO<formula><inf><roman>20</roman></inf></formula> crystal with improved discrimination</title>

Vallmitjana¹,

Cartwright

Carnicer³

et al. 1996

SPIE Proceedings

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An experimental realisation of optical correlation for pattern recognition by using phase only filters as a reference in a real-time joint transform correlator is presented. The correlator operates with a liquid crystal television as the input and a photorefractive crystal at the recording plane. The use of photorefractive materials such as Bi12SiO as a dynamic holographic medium is becoming an interesting alternative to current liquid crystal based modulators in real-time optical image processing. In order to improve the performance of detection, the phase-only filter has been taken into account. Usually, this filter is used in the frequency domain, although it can be employed in the object space, becoming the reference in a joint transform correlator. As this filter requires negative values, holographic codification methods are required to encode it. Experimental results are presented and compared with those obtained with the classical matched filter.

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“…A study of the complex characteristics of the imaging elements was performed by Soutar, et al 9 As the hybrid optical correlator requires that both the magnitude and phase of the information be used, the information provided by this article was particularly useful. Soutar and his collaborators determined optimum driving parameters and limitations when using the Epson SLMs as both input and 268/SPIE Vol.…”

Section: Optical Implementation Of the Modified Algorithmmentioning

confidence: 98%

<title>Hybrid optical system for frequency-domain texture classification of imagery</title>

Easton

Comeau

Brown

et al. 1994

Automatic Object Recognition IV

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An algorithm for segmenting images based on local texture properties and which requires only linear filtering operations has been described in a previous paper. We now report on the implementation of this algorithm in a hybrid electro-optical system which performs the linear filtering operations in the spatial frequency domain. Liquid-crystal video displays (LCDs) are used for input of the image and the frequency-domain filter. The system has the potential for rapid segmentation of simple images by texture properties. . INTRODUCTIONNatural scenes often are composed of irregularly shaped macroscopic regions which are distinguished only by the small-scale ("microscopic") local order of pixel gray levels. This local patterning commonly is called 'texture", and may be described as a pseudoperiodic nonrandom arrangement of gray levels'. Identification and segmentation of these textural regions is a common image processing problem, particularly in remote sensing.The information about the texture of a region appears in the Fourier spectrum as concentrations of amplitude about the spatial frequency(s) characteristic of the microscopic texture pattern. The shape of the macroscopic region which contains that texture determines the local distribution of amplitude in the Fourier spectrum about the characteristic spatial frequency(s). The spectrum of a strictly periodic texture pattern will exhibit sharp concentrations of amplitude at the characteristic spatial frequencies in the spectrum, while that of a pseudoperiodic texture will be less well delineated.Stromberg and Farr2 described an algorithm for segmenting regions based on texture by applying a sequence of annular filters to the Fourier spectrum to identify and isolate regions in the image that contain specific texture patterns. Use of annular filters ensures that the result is insensitive to orientation of the texture pattern, but the raw filtered images include the carrier frequencies of the texture components. The carrier was removed by a subsequent lowpass filter applied to the magnitude of the bandpass filtered images. The resulting set of filtered images can be used to define a signature for each texture class. The method was used to discriminate geological textures in synthetic aperture radar (SAR) images.Previously, we reported a modified algorithm which gives results similar to those of Stromberg and Farr but may be implemented more easily in a coherent electro-optical system3. The method generates a large number of images from single-sideband bandpass filters. By computing the magnitude (or squared magnitude) of the filtered images, the lowpass filter required by the Stromberg method is eliminated. The bandpass-filtered magnitudes within each passband may be digitized and summed to create a single image for each annular band analogous to the images obtained by the earlier method. O-8194-1538-3/94/$6.OO SPIE Vol. 2234 / 265 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/24/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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<title>Complex characterization of the Epson liquid crystal television</title>

Cited by 11 publications

References 0 publications

Fullin-situcharacterization of spatial light modulators in an optical correlator. Filter adaptation to operating curves

Fullin-situcharacterization of spatial light modulators in an optical correlator. Filter adaptation to operating curves

<title>Joint transform correlator using photorefractie Bi<formula><inf><roman>12</roman></inf></formula>SiO<formula><inf><roman>20</roman></inf></formula> crystal with improved discrimination</title>

<title>Hybrid optical system for frequency-domain texture classification of imagery</title>

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