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One of the problems associated with the automatic image processing of satellite photographs such as weather maps is the need for image registration; that is, the fitting of a map that has some translational and rotational bias to a known data base. This paper investigates a least square method of image registration using an image that has been converted into a boundary map with a pixel representation 1 for land, -1 for water and zero for cloud pixels. A sampled correlation array is constructed by shifting the weather map to locations on a given grid, centered around a sampled correlation peak, and performing an accumulation of the pixel-by-pixel comparisons between the weather map and its data base over the whole map or a smaller search window. A least square approximation 0 f the translational and rotational bias is performed using the data from this sampled correlation array, fitted against the shape of an elliptical cone.

The requirement for a fast automated correlation algorithm for registration of satellite images is discussed. An overview of current registration techniques is presented indicating a correlator, matching binary maps compressed from the original imagery, may provide the required throughput when implemented with a dedicated hardware/processor. An actual registration problem utilizing GOES digitally processed imagery is chosen and defined. The realization of a fast correlator, matching image input data with sampled data base reference image data in real time is considered.

A microcomputer controller has been developed to operate a stereofluoroscopic system that is to be built at Virginia Polytechnic Institute and State University. The purpose of the controller is to provide the radiologist with the maximum amount of fluoroscopic information with the minimum amount of radiation exposure. The enhancement of the fluoroscopic information has been brought about through the implementation of real-time stereoscopic visualization. Stereoscopic visualization has been achieved by using PLZT crystal technology. The computer will control two grid-pulsed x-ray sources, an image intensifier, a solid-state video camera, a video monitor and the PLZT goggles to provide a stereoscopic image. Dose reduction should be obtained through the use of the computer as the controlling mechanism. Two storage tubes will be synchronized with the fluoroscopic apparatus to allow repeated replay of an instantaneous fluoroscopic image. A wide range of update rates can be selected by the radiologist to yield maximum radiation exposure savings. This stereofluoroscope is expected to provide real-time analysis with radiation exposures less than or equal to those achieved in conventional two-dimensional fluoroscopic analyses. / Master of Science

The performance of two-dimensional image processing systems has been well documented. In this thesis we study the performance of three-dimensional imaging systems. Such a study helps in understanding the fundamental restrictions of the propagation of three-dimensional (3-D) wavefields. The knowledge of the obtainable 3-D wave structures are useful for applications such as 3-D data acquisition, material processing, radiation therapy, radiative non-invasive surgery, 3-D microscopy and robotic vision. This thesis primarily deals with some investigations of 3-D optical transfer functions (OTFs). Specific emphasis has been made on the interpretation of 3-D wavefield distributions as an extension of 2-D defocused OTFs and also the interpretations of 3-D diffraction images from convolution relations. / Master of Science

An edge-based segmentation scheme (i.e. boundary detector) for nuclear medicine images has been developed and consists of a multiresolutional Gaussian-based edge detector working in conjunction with a modified version of Nilsson's A* graph-search algorithm. A multiresolution technique of analyzing the edge-signature plot (edge gradient versus resolution scale) allows the edge detector to match an appropriately sized edge operator to the edge structure in order to measure the full extent of the edge and thus gain the best compromise between noise suppression and edge localization. The graph-search algorithm uses the output from the multiresolution edge detector as the primary component in a cost function which is then minimized to obtain the boundary path. The cost function can be adapted to include global information such as boundary curvature, shape, and similarity to prototype to help guide the boundary detection process in the absence of good edge information.

Thesis (MSc)--Stellenbosch University, 2000. / ENGLISH ABSTRACT: A digital portal X-ray imaging system was developed to replace the radiographic X-ray films currently used for patient position verification at the National Accelerator Centre (NAC) proton therapy facility. The main advantage of a digital system is the short time in which the image can be obtained. Other advantages include optimisation of the image display, effective archiving of the digital images, access from various locations through data networks, and lower operational costs. The digital system described in this thesis consists of a Gd202S:Tb scintillator screen for converting X-rays to visible light, a protected aluminum front silvered mirror to direct the light to a Charge Coupled Device (CCD) camera for capture and a personal computer for data acquisition, processing and display. Compared with other digital imaging systems, this is a simple, compact and affordable system. The properties of the various components were investigated. The Rarex G-130 (Gd202S:Tb) scintillation screen was chosen for its good spatial resolution, high emission efficiency and good matching between the spectral emission wavelength peak and the quantum efficiency of the CCD camera. The spatial resolution measured for the system with a field of view (FOV) of 290 x 190 mnr' is 1.3 lp/mm, which can be improved by increasing the CCD chip resolution or decreasing the field of view, since the CCD camera limits the spatial resolution. Intrinsic detector noise determines the lower limit of the dynamic range of the detector and is reduced by cooling the CCD camera. A dark current exposure is subtracted from the image to remove the bias signal and background signal level mainly caused by thermal noise. Photon noise, beam in-homogeneity and efficiency variations across the CCD chip are removed by a flat field correction. The digital images obtained with this system compare very well with the currently used radiographic film images and they are satisfactory for the purpose of patient position verification. Using the digital system it is possible to reduce the patient dose by 19 % and still obtain satisfactory image quality. / AFRIKAANSE OPSOMMING: 'n Digitale X-straalafbeeldingstelsel is ontwikkel om die radiografiese X-straalfilm wat tans gebruik word vir die kontrolering van die pasientposisionering voor die toediening van protonterapie by die Nasionale Versnellersentrum, te vervang. Die voordeel van die digitale sisteem is dat die beelde feitlik onmiddellik beskikbaar is. Verdere voordele sluit die optimisering van die vertoon van beeldkontras, effektiewe liassering, vinnige bereik deur datanetwerke en lae lopende kostes in. Die digitale sisteem beskryf in die tesis bestaan uit 'n gadolinium oksi-sulfied (Gd202S:Tb) sintillasieskerm wat X-strale omskakel na sigbare lig, 'n eerste-oppervlak aluminiumspieël wat die lig na 'n digitale kamera (CCD kamera) weerkaats en In persoonlike rekenaar vir dataverwerwing, verwerking en vertoon. Vergeleke met ander digitale stelsels is hierdie digitale beeldingstelsel eenvoudig, kompak en bekostigbaar. Die eienskappe van die verskillende komponente van die stelsel is ondersoek. Die Rarex G- 130 (Gd202S:Tb) sintillasieskerm IS gekies vanweë goeie resolusie, hoë emissiedoeltreffendheid en die hoë omsettingsdoeltreffendheid van die digitale kamera by die spektrale emissiegolflengte van dié sintillasieskerm. Die ruimtelike oplosvermoë van die stelsel is bepaal met In veldgrootte van 290 x 190 mnr' as 1.3 lynpare per millimeter. Die ruimtelike oplosvermoë kan verhoog word deur die kameraresolusie te verhoog of die veldgrootte te verklein, omdat die resolusie van die kamera tans die oplosvermoë van die stelsel beperk. Intrinsieke ruis van die detektor beperk die onderste grens van die dinamiese reikwydte van die detektor en kan verminder word deur die kamera te verkoel. 'n Donkerstroom-beeld word van die X-straalbeelde afgetrek om die voorspanningsein en die agtergrondsein, wat hoofsaaklik veroorsaak word deur termiese ruis, te verwyder. Ruis wat ontstaan as gevolg van fluktuasies in die aantal fotone, nie-homogeniteite in die bundel of variasie van die sensitiwiteit in die skerm word verwyder met behulp van 'n plat vlak beeld. Die digitale beelde verkry met die stelsel vergelyk goed met die beelde wat tans op film geneem word en die beeldkwalitiet is voldoende vir die kontrolering van die pasientopstelling. Dit is moontlik om die pasiëntdosis met 19 % te verminder en steeds voldoende beeldkwaliteit te verkry.

Approved for public release, distribution is unlimited / This thesis assesses the performance of the Naval Postgraduate School Aerosol Optical Depth (NPS AOD) model utilizing very high spatial resolution QuickBird (QB) satellite data. QuickBird derived AOD results are compared to other satellite and ground based AOD results, specifically, AErosol RObotic NETwork (AERONET), MODerate resolution Imaging Spectroradiometer (MODIS), Multi-angle Imaging SpectroRadiometer (MISR), and Advanced Very High Resolution Radiometer (AVHRR). Data is collected around Sir Bu Nuair Island, United Arab Emirates in September 2004 as part of the UAE2 Campaign. Satellite measured radiances are calibrated and due to spatial resolution differences between sensors, modal radiances are calculated for areas matching the highest resolution sensor. The AOD model is based on AVHRR wavelengths; hence, the modal satellite measured radiances are linearly extrapolated to the effective wavelengths of AVHRR. Results show application of the NPS AOD model to QuickBird data yields findings that are consistent with other satellite and ground based retrievals. In general, the NPS AOD model works well for nadir and near-nadir view angles, but not for high zenith angles. / Lieutenant Commander, United States Navy

"November 2004" / Includes bibliographical references (leaves 283-293) / xxix, 293 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Electrical and Electronic Engineering, 2004

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