ISSN:0030-3909    

DOI:10.1080/713818240

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818235

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Image formation in the two-beam Fraunhofer holographic process is theoretically and experimentally treated from the viewpoint of coherence theory. It becomes clear that reconstructed images are very much degraded by a degree of spatial coherence in the illuminating beams during recording and reconstruction of a hologram and the distortion term (zero-order diffraction pattern) is also reduced by the partially coherent light. The two-point resolution problem is treated using partially coherent illumination in the recording and reconstructing processes of the hologram. A new method for measuring the spatial coherence by the Fraunhofer holographic method is proposed and experimentally examined. This technique is compared with a conventional double-pinhole interference method.

ISSN:0030-3909    

DOI:10.1080/713818236

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A circular array of sensors can be used to measure, instant by instant, the distribution of sources in 360° of azimuth. This information is extracted from the signals received in the sensors, usually by an electronic processer. Here, an optical processer based on a spatial frequency filtering system is proposed. A light modulator couples the signals into the optical system, which forms an image of the azimuthal distribution of sources; filtering or spectrum analysis of the signals is also performed. Such an optical processer could replace very many electronic components. Application of the technique to a radar is discussed, and the preparation of a spatial filter to provide both beam-forming and pulse compression is considered. In this and other applications the chief problem will be to develop an appropriate light modulator.

ISSN:0030-3909    

DOI:10.1080/713818237

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

A coherent system suitable for performing matched filtering is described. The optical processing of signals received from a directional aerial system using circular arrays is assessed. Details are given of the spatial filter required and of the comparison of processer output with the theoretically determined distribution.

ISSN:0030-3909    

DOI:10.1080/713818242

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

The tec.hniqucs of image processing by the filtering of spatial frequencies have frequently used filters that either transmit or block spatial frequencies absolutely, that is binary filters. The operation of these filters is then discussed in the context of the specific application or with reference to a particular object. The purpose of this paper is to present a general analysis of the simplest form of binary filter, acting in a coherent optical system forming an image of a unit step function, and then to demonstrate that the operation of compound binary filters may be derived from this analysis. In all, five binary filters are discussed and the distribution of intensity in the image of a unit step function for each filter is presented.

ISSN:0030-3909    

DOI:10.1080/713818241

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

摘要:

Many techniques have been applied in image enhancement. Some of these are briefly reviewed here. Note that many of them may be classed under the general heading of ‘linear filtering’. To evaluate any image enhancement procedure,quantitativeimage assessment criteria are required. The criteria applicable to systems meant to convey information are reviewed here. It is noted that large areas of application can be covered by two, relatively simple, criteria: signal to noise ratio and mean squared deviation. Image optimization is investigated from the point of view of least squared deviation with both linear filters and scale change considered. The latter is treated in some detail. The term ‘image restoration’ is proposed to cover efforts to minimize the squared deviation of the actual image from its ideal version.

ISSN:0030-3909    

DOI:10.1080/713818239

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor

ISSN:0030-3909    

DOI:10.1080/713818238

出版商:Taylor & Francis Group    

年代:1970

数据来源: Taylor