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Dissertations / Theses on the topic 'Wavelet transforms'

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Published: 4 June 2021

Last updated: 7 September 2023

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1

Shi, Fangmin. "Wavelet transforms for stereo imaging." Thesis, University of South Wales, 2002. https://pure.southwales.ac.uk/en/studentthesis/wavelet-transforms-for-stereo-imaging(65abb68f-e30b-4367-a3a8-b7b3df85f566).html.

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Stereo vision is a means of obtaining three-dimensional information by considering the same scene from two different positions. Stereo correspondence has long been and will continue to be the active research topic in computer vision. The requirement of dense disparity map output is great demand motivated by modern applications of stereo such as three-dimensional high-resolution object reconstruction and view synthesis, which require disparity estimates in all image regions. Stereo correspondence algorithms usually require significant computation. The challenges are computational economy, accuracy and robustness. While a large number of algorithms for stereo matching have been developed, there still leaves the space for improvement especially when a new mathematical tool such as wavelet analysis becomes mature. The aim of the thesis is to investigate the stereo matching approach using wavelet transform with a view to producing efficient and dense disparity map outputs. After the shift invariance property of various wavelet transforms is identified, the main contributions of the thesis are made in developing and evaluating two wavelet approaches (the dyadic wavelet transform and complex wavelet transform) for solving the standard correspondence problem. This comprises an analysis of the applicability of dyadic wavelet transform to disparity map computation, the definition of a waveletbased similarity measure for matching, the combination of matching results from different scales based on the detectable minimum disparity at each scale and the application of complex wavelet transform to stereo matching. The matching method using the dyadic wavelet transform is through SSD correlation comparison and is in particular detailed. A new measure using wavelet coefficients is defined for similarity comparison. The approach applying a dual tree of complex wavelet transform to stereo matching is formulated through phase information. A multiscale matching scheme is applied for both the matching methods. Imaging testing has been made with various synthesised and real image pairs. Experimental results with a variety of stereo image pairs exhibit a good agreement with ground truth data, where available, and are qualitatively similar to published results for other stereo matching approaches. Comparative results show that the dyadic wavelet transform-based matching method is superior in most cases to the other approaches considered.

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2

Parker, Kristen Michelle. "Watermarking with wavelet transforms." Master's thesis, Mississippi State : Mississippi State University, 2007. http://library.msstate.edu/etd/show.asp?etd=etd-11062007-153859.

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3

Rivera, Vega Nestor. "Reservoir characterization using wavelet transforms." Texas A&M University, 2003. http://hdl.handle.net/1969.1/482.

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Automated detection of geological boundaries and determination of cyclic events controlling deposition can facilitate stratigraphic analysis and reservoir characterization. This study applies the wavelet transformation, a recent advance in signal analysis techniques, to interpret cyclicity, determine its controlling factors, and detect zone boundaries. We tested the cyclostratigraphic assessments using well log and core data from a well in a fluvio-eolian sequence in the Ormskirk Sandstone, Irish Sea. The boundary detection technique was tested using log data from 10 wells in the Apiay field, Colombia. We processed the wavelet coefficients for each zone of the Ormskirk Formation and determined the wavelengths of the strongest cyclicities. Comparing these periodicities with Milankovitch cycles, we found a strong correspondence of the two. This suggests that climate exercised an important control on depositional cyclicity, as had been concluded in previous studies of the Ormskirk Sandstone. The wavelet coefficients from the log data in the Apiay field were combined to form features. These vectors were used in conjunction with pattern recognition techniques to perform detection in 7 boundaries. For the upper two units, the boundary was detected within 10 feet of their actual depth, in 90% of the wells. The mean detection performance in the Apiay field is 50%. We compared our method with other traditional techniques which do not focus on selecting optimal features for boundary identification. Those methods resulted in detection performances of 40% for the uppermost boundary, which lag behind the 90% performance of our method. Automated determination of geologic boundaries will expedite studies, and knowledge of the controlling deposition factors will enhance stratigraphic and reservoir characterization models. We expect that automated boundary detection and cyclicity analysis will prove to be valuable and time-saving methods for establishing correlations and their uncertainties in many types of oil and gas reservoirs, thus facilitating reservoir exploration and management.

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4

Silva, Eduardo Antonio Barros da. "Wavelet transforms for image coding." Thesis, University of Essex, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282495.

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5

Choe, Gwangwoo. "Merged arithmetic for wavelet transforms /." Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004235.

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6

Boettcher, Joseph Bradley. "VIDEO CODING WITH 3D WAVELET TRANSFORMS." MSSTATE, 2008. http://sun.library.msstate.edu/ETD-db/theses/available/etd-11082007-072709/.

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Video coding systems based on 3D wavelet transforms offer several advantages over traditional hybrid video coders. This thesis proposes two 3D wavelet-based video-coding approaches. In the first approach, motion compensation with redundant-wavelet multihypothesis, in which multiple predictions that are diverse in transform phase contribute to a single motion estimate, is deployed into the fully scalable MC-EZBC video coder. The bidirectional motion-compensated temporal-filtering process of MC-EZBC is adapted to the redundant-wavelet domain, wherein transform redundancy is exploited to generate a phase-diverse multihypothesis prediction of the true temporal filtering. In the second approach, a video coder is proposed that does not perform motion compensation explicitly, instead relying on the motion-selective characteristics of the 3D dual-tree discrete wavelet transform to isolate moving features. The transform coefficients are coded with binary set-partitioning using k-d trees in an algorithm that exploits within-subband spatiotemporal coherency as well as cross-subband correlation to achieve efficient coding.

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7

Masud, Shahid. "VLSI systems for discrete wavelet transforms." Thesis, Queen's University Belfast, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300782.

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8

Lucrecio, Armando. "ISAR imaging using Fourier and wavelet transforms." Thesis, Monterey, Calif. : Naval Postgraduate School, 2007. http://bosun.nps.edu/uhtbin/hyperion-image.exe/07Dec%5FLucrecio.pdf.

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Thesis (M.S. in Physics)--Naval Postgraduate School, December 2007.
Thesis Advisor(s): Borden, Brett ; Cristi, Roberto. "December 2007." Description based on title screen as viewed on January 23, 2008 Includes bibliographical references (p. 61-62). Also available in print.

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9

Legaspi, Joey E. "One and two dimensional discrete wavelet transforms." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/23739.

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10

Ferreira, Milton dos Santos. "Continuous wavelet transforms on the unit sphere." Doctoral thesis, Universidade de Aveiro, 2008. http://hdl.handle.net/10773/2950.

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11

Hahn, Hee Il. "Wavelet transforms for detecting microcalcifications in mammography." Diss., The University of Arizona, 1995. http://hdl.handle.net/10150/187416.

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A three-stage method based on wavelet transforms for detecting and segmenting calcifications is developed. The first stage consists of preprocessing which is realized by subtracting from the original image a Gaussian low-pass filtered version, followed by a full resolution wavelet transform. With a Laplacian of Gaussian wavelet basis the detection of microcalcifications can be nearly optimized in the details sub-bands. In fact, the two-dimensional filters which transform the input image into HH and LH + HL details sub-bands are closely related to prewhitening matched filters for detecting Gaussian objects in separable and non-separable first-order Markov noise, respectively. Two methods have been proposed to detect candidate microcalcifications. In the first method, the outputs HH and LH + HL from each octave are thresholded at some fixed percentile of the histogram of each component. Then, the detected images from all octaves are logically ORed to yield the binary map of detected pixels. The second method employs a Hotelling observer. The Hotelling discriminant is computed and then thresholded to obtain the binary map. The second stage is needed to reduce false alarms, which are reduced by analyzing the shapes of the detected pixel regions. The third stage is designed to provide an accurate segmentation of calcification boundaries. Individual microcalcifications are often greatly enhanced in the output image. FROC curves are computed from tests using a well-known database of digitized mammograms. The algorithm using the Hotelling observer shows the best overall performance in which a true positive fraction of 73% is achieved at 0.7 false positives per image.

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12

Martell, Leah A. "Data Reduction and Model Selection with Wavelet Transforms." NCSU, 2000. http://www.lib.ncsu.edu/theses/available/etd-20001106-104839.

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Martell, Leah. Data Reduction and Model Selection with Wavelet Transforms. (Under the directiion of Dr. J. C. Lu.)With modern technology massive quantities of data are being collectedcontinuously. The purpose of our research has been to develop amethod for data reduction and model selection applicable to large data setsand replicated data. We propose a novel wavelet shrinkage method byintroducing a new model selection criterion. The proposed shrinkage rule hasat least two advantages over the current shrinkage methods. First, it isadaptive to the smoothness of the signal regardless of whether it has a sparsewavelet representation, since we consider both the deterministic and thestochastic cases. The wavelet decomposition not only catches the signalcomponents for a pure signal, but de-noises and extracts these signalcomponents for a signal contaminated by external influences. Second, theproposed method allows for fine ``tuning'' based on the particular data athand. Our simulation studyshows that the methods based on the model selection criterion have better meansquare error (MSE)over the methods currently known. Two aspects make wavelet analysis the analytical tool of choice.First, thelargest in magnitude wavelet coefficients in the discrete wavelet transform (DWT) ofthe data, extract the relevant information, while discarding the resteliminates the noise component. Second, the DWT allows for a fast algorithmcalculation of computational complexity O(n). For the deterministic case we derive a bound on the approximation error of thenonlinear wavelet estimate determined by the largest in magnitude discrete wavelet coefficients. Upper bounds for the approximation error and the rateof increase of the number of wavelet coefficients in the model areobtained for the new wavelet shrinkage estimate. When the signal comes from astochastic process,a bound for the MSE is found, and for the bias of its estimate. A corrected version of the model selection criterion is introduced and some of its properties are studied. The new wavelet shrinkage is employed in the case of replicated data. An algorithm for model selection is proposed,based on which a manufacturing process can be automatically supervised for quality and efficiency. Weapply it to two real life examples.

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13

Macey, Katherine Elizabeth. "Applications of wavelet transforms to analysing medical signals." Thesis, University of Canterbury. Electrical and Electronic Engineering, 2000. http://hdl.handle.net/10092/6762.

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In this thesis, wavelets are applied to the analysis of two types of medical signals, namely infant breathing signals and ultrasound images. One-dimensional wavelets are used to quantify amplitude modulation of infant breathing that occurs during quiet sleep. Two-dimensional wavelets are used to develop enhancement techniques in the wavelet domain, tailored to ultrasound images. The development of wavelets is described from the backgrounds of mathematics, signal processing and sub-band coding. One-dimensional wavelets are defined for both continuous and discrete cases. Two-dimensional wavelets are developed for both separable and non-separable classes. The construction of both one- and two-dimensional wavelets is described, and examples of wavelets that are used in subsequent analyses are presented. The analysis of breathing signals provides information for understanding the physiology of breathing. The wavelet domain is shown to isolate frequency characteristics of breathing signals, as well as indicating the temporal position of those characteristics in the signal. Some of the characteristics that were measured were not distinguished in the original signals. The extent of constant frequency components due to amplitude modulation of the principal breathing rate is quantified. Breathing in infants is of particular interest, as it may provide insight into the cause of Sudden Infant Death Syndrome (SIDS), or cot death. Studies of infants who later succumbed to SIDS, or were at high risk for SIDS, and infants at low risk for SIDS were carried out. The infants who later succumbed to SIDS and those at high risk for SIDS showed different characteristics in the wavelet domain compared to infants at low risk for SIDS. As well as implying that there may be a difference in the physiologies of infants at high and low risk for SIDS, this result confirms that wavelets can be used to analyse breathing signals and produce meaningful results. Ultrasound images typically contain artefacts and low contrast between features of interest and often exhibit a noisy background. The aim of any enhancement procedure is to reduce the contributions from noise and artefacts and increase the contrast between the features of interest and the background. A method to objectively measure improvements in image quality is described, although this attempt achieved mixed results. Separable and non-separable two-dimensional wavelets are used with enhancement functions to improve the image quality. Enhancement schemes, including noise reduction and contrast enhancement, are developed. A spatially varying contrast enhancement function is also developed. Noise reduction, in combination with the spatially varying contrast enhancement function, produces an image that reduces the existing artefacts in the image and increases the contrast for the features of interest. Wavelets are shown to be a useful tool for the analysis of infant breathing signals and for improvement of image quality in ultrasound images.

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14

NiBouch, M. "Design and FPGA implementations for discrete wavelet transforms." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268365.

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15

Erdemir, Alper. "Data compression by using wavelet transforms and vector quantization." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA272763.

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16

Zhang, Yuanhua. "Wavelet transforms, neural networks and migration applied to magnetotellurics." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq23897.pdf.

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17

Singh, Inderpreet. "New wavelet transforms and their applications to data compression." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape4/PQDD_0011/NQ52773.pdf.

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18

Tourshan, Khaled. "Parameterization of slant and slantlet/wavelet transforms with applications /." Thesis, Connect to Dissertations & Theses @ Tufts University, 2003.

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Thesis (Ph.D.)--Tufts University, 2003.
Adviser: Joseph P. Noonan. Submitted to the Dept. of Electrical Engineering. Includes bibliographical references (leaves 149-149). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

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19

Pashine, Rajat. "Signal analysis for multiple target materials through wavelet transforms." Diss., Rolla, Mo. : Missouri University of Science and Technology, 2010. http://scholarsmine.mst.edu/thesis/pdf/Pashine_09007dcc8074b5e0.pdf.

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Thesis (M.S.)--Missouri University of Science and Technology, 2010.
Vita. The entire thesis text is included in file. Title from title screen of thesis/dissertation PDF file (viewed April 8, 2010) Includes bibliographical references (p. 46-47).

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20

Overdyk, Howard F. "Detection and estimation of frequency hopping signals using wavelet transforms." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1997. http://handle.dtic.mil/100.2/ADA339336.

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Thesis (M.S. in Electrical Engineering) Naval Postgraduate School, Sept. 1997.
"September 1997." Thesis advisor(s): Monique P. Fargues, Ralph Hippenstiel. Includes bibliographical references (p. 99-100). Also Available online.

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21

Alarcon, Aquino Vicente. "Anomaly detection and prediction in communication networks using wavelet transforms." Thesis, Imperial College London, 2003. http://hdl.handle.net/10044/1/11475.

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22

Meejun, Naowarut. "The application of wavelet transforms to many-body particle interactions." Thesis, University of Surrey, 2008. http://epubs.surrey.ac.uk/843558/.

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Wavelet transforms are used to explore the dynamic evolution of granular material by post-processing data from DEM simulations. Data sets generated from two different physical scenarios were analysed: particles in vibration cells and samples under compression. It is shown how the wavelet multiresolution analysis (MRA) helps to reveal the particle motions within a vibration box subject to applied vibrations. Two combinations of amplitude and frequency vibration were applied in this work: low frequency with high amplitude and high frequency with low amplitude. Both cases give the same acceleration amplitude of approximately 7.8g where g is the acceleration due to gravity and both mono-sized particles and binary mixture were considered. The root mean square of the fluctuating velocity and the packing fraction of the two data sets are also consistent with the analysis results of the wavelets technique. Furthermore, it is shown how the MRA techniques were used to capture the position of inhomogeneities in granular material response by analysis of data sets from simulations of biaxial and triaxial compression tests. In the case of biaxial compression, results from the wavelet analysis are compared with plots of the cumulative rotation of the particles. In the triaxial compression test where a bonded material is considered the wavelet analysis is compared with plots of the position of broken bonds in the sample. Moreover, it is shown that the MRA techniques can aid in finding the time/strain scales on which significant events occur. This information could be used to determine how frequently to output data on stress, strain-rate (velocity) and packing voidage distributions during compression, shear and flow of the granular bulk. Furthermore, the wavelet technique should be considered for applications involving quantitative analysis of experimental data generated by the other advanced experimental techniques such as photo-elasticity and X-ray computed tomography techniques.

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Li, Xin-Gong. "Application of wavelet transforms to seismic data processing and inversion." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq25094.pdf.

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24

Adams, Michael David. "Reversible wavelet transforms and their application to embedded image compression." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk2/tape17/PQDD_0007/MQ34478.pdf.

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25

Chen, Guangyi. "Applications of wavelet transforms in pattern recognition and de-noising." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape7/PQDD_0006/MQ43552.pdf.

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26

Sullivan, Terry J. "Application of wavelet transforms to sonar signal detection and estimation." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0001/MQ44860.pdf.

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27

Nayan, Mohd Yunus. "A family of stereoscopic image compression algorithms using wavelet transforms." Thesis, Loughborough University, 2004. https://dspace.lboro.ac.uk/2134/36113.

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With the standardization of JPEG-2000, wavelet-based image and video compression technologies are gradually replacing the popular DCT-based methods. In parallel to this, recent developments in autostereoscopic display technology is now threatening to revolutionize the way in which consumers are used to enjoying the traditional 2-D display based electronic media such as television, computer and movies. However, due to the two-fold bandwidth/storage space requirement of stereoscopic imaging, an essential requirement of a stereo imaging system is efficient data compression. In this thesis, seven wavelet-based stereo image compression algorithms are proposed, to take advantage of the higher data compaction capability and better flexibility of wavelets.

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Paya, Basir Abdul. "Vibration condition monitoring and fault diagnostics of rotating machinery using artificial neural networks." Thesis, Brunel University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390220.

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Prosser, Robert. "Numerical methods for the computation of combustion." Thesis, University of Cambridge, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340975.

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Lutz, Steven S. "Hokua – A Wavelet Method for Audio Fingerprinting." Diss., CLICK HERE for online access, 2009. http://contentdm.lib.byu.edu/ETD/image/etd3247.pdf.

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31

Fekri, Faramarz. "Finite-field wavelet transforms and their application to error-control coding." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/15799.

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32

Game, Adrian Colin. "Design and real-time hardware implementation of binary integer wavelet transforms." Thesis, University of Warwick, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.487814.

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This thesis explores methods to construct efficient wavelet transforms for operation on Field Programmable Gate Array (FPGA) devices. Additionally the wavelets designed have been used in an audio watermarking application.

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Stromme, Oyvind. "On the applicability of wavelet transforms to image and video compression." Thesis, University of Strathclyde, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.366529.

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Luo, Gaoyong. "Application of wavelet transforms to vibration analysis for wood machining processes." Thesis, Bucks New University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390816.

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Bleiler, Sarah K. "Orthogonal filters and the implications of wrapping on discrete wavelet transforms." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002676.

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He, Chao. "Advanced wavelet application for video compression and video object tracking." Connect to resource, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1125659908.

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Thesis (Ph. D.)--Ohio State University, 2005.
Title from first page of PDF file. Document formatted into pages; contains xvii, 158 p.; also includes graphics (some col.). Includes bibliographical references (p. 150-158). Available online via OhioLINK's ETD Center

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Brooks, William Allen. "Ultra-wideband radar transient signal detection using time-frequency and wavelet transforms." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School; Available from the National Technical Information Service, 1992. http://edocs.nps.edu/npspubs/scholarly/theses/1992/Dec/92Dec_Brooks.pdf.

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Kudumakis, Panos E. "Synthesis and coding of audio signals using wavelet transforms for multimedia applications." Thesis, King's College London (University of London), 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.343479.

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Hennenfent, Gilles, and Felix J. Herrmann. "Three-term amplitude-versus-offset (avo) inversion revisited by curvelet and wavelet transforms." Society of Exploration Geophysicists, 2004. http://hdl.handle.net/2429/615.

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We present a new method to stabilize the three-term AVO inversion using Curvelet and Wavelet transforms. Curvelets are basis functions that effectively represent otherwise smooth objects having discontinuities along smooth curves. The applied formalism explores them to make the most of the continuity along reflectors in seismic images. Combined with Wavelets, Curvelets are used to denoise the data by penalizing high frequencies and small contributions in the AVO-cube. This approach is based on the idea that rapid amplitude changes along the ray-parameter axis are most likely due to noise. The AVO-inverse problem is linearized, formulated and solved for all (x, z) at once. Using densities and velocities of the Marmousi model to define the fluctuations in the elastic properties, the performance of the proposed method is studied and compared with the smoothing along the ray-parameter direction only. We show that our method better approximates the true data after the denoising step, especially when noise level increases.

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Amghar, Mohamed. "Multiscale local polynomial transforms in smoothing and density estimation." Doctoral thesis, Universite Libre de Bruxelles, 2017. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/262040.

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Un défi majeur dans les méthodes d'estimation non linéaire multi-échelle, comme le seuillage des ondelettes, c'est l'extension de ces méthodes vers une disposition où les observations sont irrégulières et non équidistantes. L'application de ces techniques dans le lissage de données ou l'estimation des fonctions de densité, il est crucial de travailler dans un espace des fonctions qui impose un certain degré de régularité. Nous suivons donc une approche différente, en utilisant le soi-disant système de levage. Afin de combiner la régularité et le bon conditionnement numérique, nous adoptons un schéma similaire à la pyramide Laplacienne, qui peut être considérée comme une transformation d'ondelettes légèrement redondantes. Alors que le schéma de levage classique repose sur l'interpolation comme opération de base, ce schéma permet d'utiliser le lissage, en utilisant par exemple des polynômes locaux. Le noyau de l'opération de lissage est choisi de manière multi-échelle. Le premier chapitre de ce projet consiste sur le développement de La transformée polynomiale locale multi-échelle, qui combine les avantages du lissage polynomial local avec la parcimonie de la décomposition multi-échelle. La contribution de cette partie est double. Tout d'abord, il se concentre sur les largeurs de bande utilisées tout au long de la transformée. Ces largeurs de bande fonctionnent comme des échelles contrôlées par l'utilisateur dans une analyse multi-échelle, ce qui s'explique par un intérêt particulier dans le cas des données non-équidistantes. Cette partie présente à la fois une sélection de bande passante optimale basée sur la vraisemblance et une approche heuristique rapide. La deuxième contribution consiste sur la combinaison du lissage polynomial local avec les préfiltres orthogonaux dans le but de diminuer la variance de la reconstruction. Dans le deuxième chapitre, le projet porte sur l'estimation des fonctions de densité à travers la transformée polynomiale locale multi-échelle, en proposant une reconstruction plus avancée, appelée reconstruction pondérée pour contrôler la propagation de la variance. Dans le dernier chapitre, On s’intéresse à l’extension de la transformée polynomiale locale multi-échelle dans le cas bivarié, tout en énumérant quelques avantages qu'on peut exploiter de cette transformée (la parcimonie, pas de triangulations), comparant à la transformée en ondelette classique en deux dimension.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

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41

MALEGORI, GIOVANNA. "Wavelet transform analysis in thermally excited dinamic force spectroscopy." Doctoral thesis, Università degli Studi di Milano, 2010. http://hdl.handle.net/2434/150135.

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The use of wavelet transforms in thermally excited dynamic force spectroscopy allows to get insights into fundamental thermodynamical properties of the cantilever Brownian motion as well as giving a meaningful and intuitive representation of the cantilever dynamics in time and frequency caused by the interaction with long and short-range forces. It is remarkable the possibility to carry out measurements across the jump-to-contact transition without interruption, providing information on the short-range adhesion forces and elastic properties of the surface.

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42

Orme, Wesley John. "Cross sections used to elucidate differences in wavelet transforms of ground force reactions." [Boise, Idaho] : Boise State University, 2009. http://scholarworks.boisestate.edu/td/70/.

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43

Cho, Dongwook. "Image denoising using wavelet transforms." Thesis, 2004. http://spectrum.library.concordia.ca/8141/1/MQ94737.pdf.

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Image denoising is a fundamental process in image processing, pattern recognition, and computer vision fields. The main goal of image denoising is to enhance or restore a noisy image and help the other system (or human) to understand it better. In this thesis, we discuss some efficient approaches for image denoising using wavelet transforms. Since Donoho proposed a simple thresholding method, many different approaches have been suggested for a decade. They have shown that denoising using wavelet transforms produces superb results. This is because wavelet transform has the compaction property of having only a small number of large coefficients and a large number of small coefficients. In the first part of the thesis, some important wavelet transforms for image denoising and a literature review on the existing methods are described. In the latter part, we propose two different approaches for image denoising. The first approach is to take advantage of the higher order statistical coupling between neighbouring wavelet coefficients and their corresponding coefficients in the parent level with effective translation-invariant wavelet transforms. The other is based on multivariate statistical modeling and the clean coefficients are estimated in a general rule using Bayesian approach. Various estimation expressions can be obtained by a priori probability distribution, called multivariate generalized Gaussian distribution (MGGD). The method can take into account various related information. The experimental results show that both of our methods give comparatively higher PSNR and less visual artifact than other methods.

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44

Claypoole, Roger L. Jr. "Adaptive wavelet transforms via lifting." Thesis, 2000. http://hdl.handle.net/1911/19482.

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Wavelet transforms have proven very useful for a variety of signal and image processing tasks. The wedgelet transform also shows promise for certain edge-dominated images. However, in many applications we desire to introduce adaptivity and non-linearities into the transforms. These are powerful extensions, but difficult to control within the wavelet framework. The lifting scheme provides a new, spatial intuition into the wavelet transform that simplifies the introduction of adaptivity. In this thesis, we develop several new adaptive wavelet transforms and adaptive multiresolution wedgelet transforms. The lifting construction permits control over the multiresolution properties of these transforms despite the adaptivity. We demonstrate the power of our new adaptive lifted transforms with successful applications to signal denoising and compression problems.

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Peng, Chi-Hsiang, and 彭啟翔. "Digital Watermarking Using Wavelet Transforms." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/96403732515940947467.

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碩士
國立清華大學
資訊工程學系
98
The problem of copyright protection and ownership identification is attention-getting because the Internet applications and consumer electronics products have been rapidly developed. The watermarking system can partially solve this problem. In this thesis, experiments of a watermarking system using 4 different discrete wavelet transforms were implemented. An authorized watermark, sampled from a standard normal distribution, is embedded into the wavelet coefficients of high-low and low-high subbands at level 3 of a 3-scale discrete wavelet transform. Four popular wavelet bases including Haar, Daubechies’ four, 5/3 and 9/7 are chosen for experiments. Our experiments, including scaling, median filtering, cropping, smoothing, noise adding, JPEG compression and multiple watermarks, demonstrate that our watermarking scheme satisfies fidelity, robustness, and security at a certain level.

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46

Sahambi, Jyotindra Singh. "Wavelet transforms for ECG characterization." Thesis, 1998. http://localhost:8080/xmlui/handle/12345678/2811.

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47

Hsiao, Bo, and 蕭金本. "Automatic surface inspection using wavelet transforms." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/93586104998706332680.

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碩士
元智大學
工業工程研究所
87
In this research we aim at automatic surface inspection using wavelet transforms for both structural and statistical textures. Small surface defects generally appear as local anomalies embedded in a homogeneous texture. The nature of the defects leads us toward the multi-scale and multi-resolution analysis method of wavelet transforms, which permits an efficient local spectral analysis. Wavelet transforms have been traditionally implemented for texture analysis and defect detection by selecting proper textural features in wavelet coefficient matrix. The proposed method does not reply on local texture features. It is based on an image restoration scheme using the wavelet transform. For each wavelet-transformed image, we obtain one smoothed residual sub-image and three detail sub-images, which contain fine structures with horizontal, vertical and diagonal orientation. By properly selecting the smoothed sub-image or detail images for backward wavelet transform, the restored image will remove homogeneous, periodic textures and signify only local anomalies. Experiment on structural textures such as machined surface and textile fabrics, and statistical textures such as sandpaper and leather have shown promising results using the proposed method.

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48

Sharma, Shubham. "Classification of Faults in Power Transformer using Fuzzy Logic and Wavelet Transforms." Thesis, 2014. http://ethesis.nitrkl.ac.in/5733/1/212EE5267-4.pdf.

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With the day to day increase of the power and the increasing rate of industrialization. The amount of power to be developed and the safety of the power transformers have increased manifolds. For optimum results it is required to have nearly a no – fault operation of power transformer. The objective of this thesis is to design a controller or method which could predict the unwanted outages in a small interval of time and with accuracy. The controllers like PI, PID are in use in industries over a decade and found to be very useful also. But in this case these controllers are not found to give reliable results due to the oscillating and non – periodic nature of the power transients. Hence, fuzzy controller being an intelligent controller could be used for this purpose of detection of inrush and fault current. The wavelet transform with its ability to determine information from transient signals both in frequency and time domain is also used for detailed analysis of various power transformer transients. Further it is found that wavelet transform is a very effective tool for detailed analysis of these transients and also with fuzzy logic we have obtained accurate and very useful results.

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"DESIGN AND IMPLEMENTATION OF LIFTING BASED DAUBECHIES WAVELET TRANSFORMS USING ALGEBRAIC INTEGERS." Thesis, 2013. http://hdl.handle.net/10388/ETD-2013-04-1011.

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Over the past few decades, the demand for digital information has increased drastically. This enormous demand poses serious difficulties on the storage and transmission bandwidth of the current technologies. One possible solution to overcome this approach is to compress the amount of information by discarding all the redundancies. In multimedia technology, various lossy compression techniques are used to compress the raw image data to facilitate storage and to fit the transmission bandwidth. In this thesis, we propose a new approach using algebraic integers to reduce the complexity of the Daubechies-4 (D4) and Daubechies-6 (D6) Lifting based Discrete Wavelet Transforms. The resulting architecture is completely integer based, which is free from the round-off error that is caused in floating point calculations. The filter coefficients of the two transforms of Daubechies family are individually converted to integers by multiplying it with value of 2x, where, x is a random value selected at a point where the quantity of losses is negligible. The wavelet coefficients are then quantized using the proposed iterative individual-subband coding algorithm. The proposed coding algorithm is adopted from the well-known Embedded Zerotree Wavelet (EZW) coding. The results obtained from simulation shows that the proposed coding algorithm proves to be much faster than its predecessor, and at the same time, produces good Peak Signal to Noise Ratio (PSNR) at very low bit rates. Finally, the two proposed transform architectures are implemented on Virtex-E Field Programmable Gate Array (FPGA) to test the hardware cost (in terms of multipliers, adders and registers) and throughput rate. From the synthesis results, we see that the proposed algorithm has low hardware cost and a high throughput rate.

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50

Sripathi, Deepika Foo Simon Y. "Efficient implementations of discrete wavelet transforms using FPGAs." Diss., 2003. http://etd.lib.fsu.edu/theses//available/etd-11242003-185039.

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Thesis (M.S.)--Florida State University, 2003.
Advisor: Dr. Simon Y. Foo, Florida State University, College of Engineering, Dept. of Electrical and Computer Engineering. Title and description from dissertation home page (viewed Mar. 3, 2004). Includes bibliographical references.

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