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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Maximum likelihood restoration of binary objects

Li, Ming De, 1937- January 1987 (has links)
A new approach, based on maximum likelihood, is developed for binary object image restoration. This considers the image formation process as a stochastic process, with noise as a random variable. The likelihood function is constructed for the cases of Gaussian and Poisson noise. An uphill climb method is used to find the object, defined by its "grain" positions, through maximizing the likelihood function for grain positions. In addition, some a priori information regarding object size and contour of shapes is used. This is summarized as a "neighbouring point" rule. Some examples of computer generated images with different signal-to-noise ratios are used to show the ability of the algorithm. These cases include both Gaussian and Poisson noise. For noiseless and low noise Gaussian cases, a modified uphill climb method is used. The results show that binary objects are fairly well restored for all noise cases considered.
12

Recognition of occluded objects: a dominant point approach

阮邦志, Yuen, Pong-chi. January 1993 (has links)
published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy
13

Adjustable edge quality metric and its applications

Chang, Dunkai Kyle, 1962- January 1990 (has links)
This paper first proposes a new quality metric for edge evaluation, based on six physical characteristics. These physical characteristics that affect human edge quality evaluation are continuity, smoothness, thinness, localization, detection and noisiness. The final edge quality score is a weighted linear combination of the quantified measures of these six edge quality attributes. The other feature of this edge evaluation metric is its adjustability. Through some training procedures, it can be adjusted to suit different user and application needs. In the latter part of this paper, an edge detector performance predictor is proposed. By a few initial measurements of image parameters, the performance of certain edge detectors can be predicted. Finally, the performance of several popular edge detectors is compared, under different variations of SNR, blurting and power spectrum.
14

SIFT-based image copy-move forgery detection and its adversarial attacks

Li, Yuan Man January 2018 (has links)
University of Macau / Faculty of Science and Technology. / Department of Computer and Information Science
15

Noise level estimation from single image based on natural image statistics

Dong, Li January 2018 (has links)
University of Macau / Faculty of Science and Technology. / Department of Computer and Information Science
16

Edge model based image representation and its applications. / 輪廓構圖法及其應用 / Edge model based image representation and its applications. / Lun kuo gou tu fa ji qi ying yong

January 2003 (has links)
Fong Chi Keung = 輪廓構圖法及其應用 / 馮志強. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Fong Chi Keung = Lun kuo gou tu fa ji qi ying yong / Feng Zhiqiang. / Acknowledgement --- p.i / Abstract --- p.ii / Contents --- p.iv / List of Figures --- p.vi / List of Tables --- p.xi / Chapter Chapter 1. --- Introduction --- p.1-1 / Chapter 1.1. --- A Brief Review on Image Representation --- p.1-1 / Chapter 1.2. --- Objective of the Research Work --- p.1-3 / Chapter 1.3. --- Organization of the Thesis --- p.1-4 / Chapter 1.3.1. --- The edge-model based representations --- p.1-4 / Chapter 1.3.2. --- The applications of edge-model based representation --- p.1-5 / Chapter Chapter 2. --- Review on the Edge Models --- p.2-1 / Chapter 2.1. --- Introduction --- p.2-1 / Chapter 2.2. --- Review on Existing Edge Models --- p.2-1 / Chapter 2.2.1. --- Unit-Step Model --- p.2-2 / Chapter 2.2.2. --- Ramp Model --- p.2-3 / Chapter 2.2.3. --- Hyperbolic Tangent Model --- p.2-4 / Chapter 2.2.4. --- van Beek's Edge Model --- p.2-5 / Chapter 2.3. --- Methodology --- p.2-6 / Chapter 2.3.1. --- Model Parameter Estimation in van Beek's model --- p.2-6 / Chapter 2.3.2. --- Model Parameter Estimation in other models --- p.2-9 / Chapter 2.3.3. --- Image Reconstruction --- p.2-10 / Chapter 2.3.4. --- Intensity Surface Reconstruction --- p.2-11 / Chapter 2.4. --- Summary --- p.2-18 / Chapter Chapter 3. --- Improved Edge-Model-Based representation --- p.3-1 / Chapter 3.1 --- Reconstruction Artifacts --- p.3-1 / Chapter 3.2 --- The improved edge model --- p.3-2 / Chapter 3.2.1. --- Minimum Reconstruction Range (MRR) --- p.3-2 / Chapter 3.2.2. --- Sub-pixel Estimation (SPE) --- p.3-4 / Chapter 3.3. --- Experimental Results --- p.3-11 / Chapter 3.3.1. --- Comparison between van Beek's Method and LSF in Parameters Estimation --- p.3-11 / Chapter 3.3.2. --- Comparison among Intensity Surface Reconstruction Methods --- p.3-13 / Chapter 3.3.3. --- Comparison among Edge Models --- p.3-18 / Chapter 3.4. --- Conclusions --- p.3-22 / Chapter Chapter 4. --- Edge-Model-Based Post-processing for SPIHT coded Images --- p.4-1 / Chapter 4.1 --- Introduction --- p.4-1 / Chapter 4.2. --- Brief review on the Post-processing --- p.4-2 / Chapter 4.3. --- Experimental Results --- p.4-5 / Chapter 4.4. --- Conclusions --- p.4-6 / Chapter Chapter 5. --- Edge-Model-Based Interpolation --- p.5-1 / Chapter 5.1 --- Introduction --- p.5-1 / Chapter 5.2 --- Objectives --- p.5-6 / Chapter 5.3 --- Algorithm --- p.5-6 / Chapter 5.3.1. --- Edge Location Estimation --- p.5-7 / Chapter 5.3.2. --- Edge Width Correction --- p.5-10 / Chapter 5.3.3. --- Confident Function --- p.5-16 / Chapter 5.4 --- Experimental Results --- p.5-21 / Chapter 5.5 --- Conclusions --- p.5-32 / Chapter Chapter 6. --- Edge-model-based Image Segmentation --- p.6-1 / Chapter 6.1. --- Introduction --- p.6-1 / Chapter 6.2. --- A brief review on segmentation --- p.6-1 / Chapter 6.3. --- Objectives --- p.6-2 / Chapter 6.4. --- Theory --- p.6-3 / Chapter 6.5. --- Algorithm --- p.6-6 / Chapter 6.5.1. --- Pre-segmentation by edge-model --- p.6-6 / Chapter 6.5.2. --- Grouping by Gomory-Hu Tree --- p.6-8 / Chapter 6.6. --- Experimental Results --- p.6-10 / Chapter 6.7. --- Conclusions --- p.6-15 / Chapter Chapter 7. --- Conclusions and further developments --- p.7-1 / Chapter 7.1 --- Contributions and Conclusions --- p.7-1 / Chapter 7.1.1 --- Edge-Model-Based Post-Processing for SPIHT coded images --- p.7-1 / Chapter 7.1.2 --- Edge-Model-Based Interpolation --- p.7-2 / Chapter 7.1.3 --- Edge-Model-Based Segmentation --- p.7-2 / Chapter 7.2 --- Future Development --- p.7-3 / Appendix I. Test Images used in this Research --- p.I / Bibliography --- p.III
17

Sensor Placement for Damage Localization in Sensor Networks

Firouzi, Fereshteh 01 January 2019 (has links)
The objective of this thesis is to formulate and solve the sensor placement problem for damage localization in a sensor network. A Bayesian estimation problem is formulated with the time-of-flight (ToF) measurements. In this model, ToF of lamb waves, which are generated and received by piezoelectric sensors, is the total time for each wave to be transmitted, reflected by the target, and received by the sensor. The ToF of the scattered lamb wave has characteristic information about the target location. By using the measurement model and prior information, the target location is estimated in a centralized sensor network with a Monte Carlo approach. Then we derive the Bayesian Fisher information matrix (B-FIM) and based on that posterior Cramer-Rao lower bound (PCRLB), which sets a limit on the mean squared error (MSE) of any Bayesian estimator. In addition, we develop an optimal sensor placement approach to achieve more accurate damage localization, which is based on minimizing the PCRLB. Simulation results show that the optimal sensor placement solutions lead to much lower estimation errors than some sub-optimal sensor placement solutions.
18

Physio-chemistry and rheology of Australian lentil flour and starch, and their implications for extrusion

Lee, Huang Chun, Chemical Sciences & Engineering, Faculty of Engineering, UNSW January 2007 (has links)
Among three varieties of Australian lentils, Len culinaris, Matilda had larger physical dimensions and higher protein contents, but no significant difference in chemical composition or physical dimensions existed between Digger and Cobber. Optimum conditions for the extraction of lentil flours which passed through a 0.79 mm screen were pH 9.0 at 30??C for Matilda and pH 8.5 at 35??C for both Digger and Cobber. These conditions enable a high yield of lentil starches and proteins, with minimal changes or damage to their quality. Matilda offered advantages for processors over the other varieties: it had higher protein and fibre; lower lipid; and greater foam-forming capacity and foam stability. Its starch had higher Tg, lower Tm and better expansion behaviour. All lentil starches were shear-thinning. The flow of the molten lentil starches under limited moisture content differed from starches sheared in excess moisture condition. When extruded, lentil starches offered good expansion and had higher Tg than did cereal starches in extruded products. The overall rheological behaviour of lentil flours differed from that of their corresponding starches. The lentil flours had poorer pasting quality and expansion possibly because of interference by their lipid and protein components. Starch rheological behaviour was greatly affected by the amylose/amylopectin ratio and the molecular weight of starches, while flour behaviour was more influenced by the interfering components. The ?? value obtained from capillary rheometry (CR) could be used for the screening of materials for their expansion behaviour. The CR data gave excellent agreement to the results achieved from the extruder and in predicting the expansion indices and calculated viscosity of six flour blends. In all, the quantitative and qualitative knowledge on the physico-chemistry and rheology of lentils give a better understanding of the behaviour of lentil flours and starches in the expansion of extruded products, producing suitable end products with acceptable quality and storage stability. This project highlights the lentil flour and starch rheology characteristics in view of possible application in extruded products.
19

The use of specialty sorghums for expanded snack food processing

Turner, Duane Lawrence 30 September 2004 (has links)
The physical, chemical, and antioxidant properties of extrudates prepared from specialty tannin sorghum (CSC3xR28) and Tx430 black sorghums were evaluated. White food type sorghums (ATx631xRTx436) and commercial corn meal were also extruded. Sorghums were extruded as whole kernels or cracked (broken) kernels through a Maddox MX-3001 high-friction extruder. Cracked sorghum fortified with bran (0 -50%) derived from decortication or roller-milling were also extruded. Tannin sorghums extruded similarly to white food-type sorghums, with very little difference in extrudate quality. Cracking the sorghums produced lower feed rates, higher specific mechanical energy (SME) and extrudates that were less dense, more expanded, and softer than whole kernel extrudates. Whole and cracked sorghum materials had feed rates similar to corn meal, but lower SME. Corn meal extrudates were less dense, more expanded, and softer than sorghum extrudates. Cracked and whole black sorghum extrudates were less expanded than hi-tannin and white sorghum extrudates, due to the black sorghum's soft endosperm and thick, fibrous pericarp. With increased fiber, all extrudates had decreased SME and expansion, with increased bulk density and breaking force with the addition of bran. These effects, were more pronounced in extrudates containing decorticated bran vs. roller-milled bran. The decorticated bran had smaller particle size, higher density, lower endosperm content, and greater dietary fiber content than roller-milled bran. Also, increases in dietary fiber content in the extrudates were strongly correlated to increases in bran fortification in the raw feed stock. Tannin and black bran extrudates showed increased phenol, tannin (high-tannin), and antioxidants where bran was added. Phenols, tannins, and antioxidants in tannin extrudates ranged between 10.3-30.9 mg GAE/g, 7.1-55.2 CE mg/g, and 68.3-212.2 umol TE/g, respectively. Phenols and antioxidant activity in black sorghum extrudates ranged from 4.2 -7.8 mg GAE/g and 39.7 - 73.3 umol TE/g, respectively. Specialty tannin and black sorghums can be used to produce extruded snacks high in fiber and antioxidant activity. Optimum product characteristics, along with nutraceutical benefits, will need further determination.
20

Restoration of quadratically distorted images

Kwon, Tae-hwan 24 July 1990 (has links)
The problem of the restoration of quadratically distorted images is considered in this investigation, based upon the fact that images formed by partially coherent illuminations are related quadratically to the amplitude of the object. Two of the most important problems in image restoration are: 1) determining the degradation characteristics of the degraded image and 2) developing restoration algorithms. Among the two classes of inverse problems, one for system identification and the second for image restoration, only the means to solve the latter are presented in this study. Since the present problem is represented by the second-order term of a Volterra series expansion, multidimensional Volterra filter theory is presented with emphasis on the properties of two-dimensional quadratic filter. The mathematics of inverse problems is presented for the purpose of image restoration, and the novel algorithms which are simple and easy to implement and robust to the ill-conditioned system in comparison to the existing algorithms are proposed. Since quadratically distorted imaging systems preclude a closed-form solution, approximate solutions are obtained through application of the proposed iterative and noniterative schemes. Images restored approximately by the proposed algorithms can be improved substantially by the use of a Newton-Raphson iteration scheme. Two typical regularization methods are presented and the truncated singular-value decomposition method is applied for the noisy image restoration. Regularized iterative restoration schemes for the noisy image restoration are also considered. Simulation examples for different issues are presented. / Graduation date: 1991

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