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Adaptive digital image data compression using RIDPCM and a neural network for subimage classification Item Type text; Thesis-Reproduction (electronic) Authors Allan, Todd Stuart, 1964- Publisher The University of Arizona. Rights Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author. Download date 24/09/2021 23:55:43 Link to Item http://hdl.handle.net/10150/278109 INFORMATION TO USERS This manuscript has been reproduced from the microfilm master. UMI films the text directly from the original or copy submitted. Thus, some thesis and dissertation copies are in typewriter face, while others may be from any type of computer printer. The quality of this reproduction is dependent upon the quality of the copy submitted. 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Contact UMI directly to order. University Microfilms International A Bell & Howell Information Company 300 North Zeeb Road, Ann Arbor, Ml 48106-1346 USA 313/761-4700 800/521-0600 Order Number 1348472 Adaptive digital image data compression using RIDPCM and a neural network for subimage classification Allan, Todd Stuart, M.S. The University of Arizona, 1992 UMI 300 N. Zeeb Rd. Ann Artor, MI 48106 ADAPTIVE DIGITAL IMAGE DATA COMPRESSION USING RIDPCM AND A NEURAL NETWORK FOR SUBIMAGE CLASSIFICATION by Todd Stuart Allan A Thesis Submitted to the Faculty of the DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING In Partial Fulfillment of the Requirements For the Degree of MASTERS OF SCIENCE WITH A MAJOR IN ELECTRICAL ENGINEERING In the Graduate College THE UNIVERSITY OF ARIZONA 1 992 STATEMENT BY AUTHOR This thesis has been submitted in partial fulfillment of requirements for an advanced degree at The University of Arizona and is deposited in the University Library to be made available to borrowers under rules of the Library. Brief quotations from this thesis are allowable without special permission, provided that accurate acknowledgment of source is made. Requests for permission for extended quotation from or reproduction of this manuscript in whole or in part may be granted by the head of the major department or the Dean of the Graduate College when in his or her judgment the proposed use of the material is in the interest of scholarship. In all other instances, however, permission must be obtained from the author. SIGNED: ^ . OS. APPROVAL BY THESIS DIRECTOR This thesis has been approved on the date shown below: Bobby R. Hunt Date Professor of Electrical and Computer Engineering 3 ACKNOWLEDGMENTS First and foremost, I would like to thank my thesis advisor, Dr. Bobby R. Hunt, for his support during this project. Without his knowledge and wisdom guiding me, this work would not have been possible. I would also like to thank Dr. Jeffrey J. Rodriguez and Dr. Robert A. Schowengerdt for their assistance throughout my graduate studies. Next, I would like to thank all of my fellow graduate students in the Neural Analysis and Imaging Lab for their support. I would especially like to thank Dave DeKruger, Eric Gifford, Michael Kiefer, and Phil Sementilli for sharing their knowledge and experience with C programming and the lab computer system. Finally, I would like to thank my family and friends for their continual support and encouragement. Special thanks goes to my wife, Maribel, for patiently and lovingly dealing with me during my graduate studies. 4 TABLE OF CONTENTS Page UST OF FIGURES 6 LIST OF TABLES 8 ABSTRACT 9 1. INTRODUCTION 10 1.1 Definition of a Digital Image 11 1.2 Concepts of Digital Image Data Compression 12 1.3 Predecessors of RIDPCM and ARIDPCM 13 1.4 Preview of Chapters 15 2. RECURSIVE IDPCM 18 2.1 Theory of RIDPCM 18 2.2 Optimum Quantization 20 2.2.1 Optimum Uniform Quantizer 21 2.2.2 Lloyd-Max Optimum Quantizer 21 2.3 Bit Rates for RIDPCM 22 2.4 Additional Algorithm Notes 23 2.5 Advantages 24 2.6 Disadvantages 25 3. ADAPTIVE RIDPCM 32 3.1 Theory of ARIDPCM 32 3.2 Subimage Classification 34 3.2.1 Image Feature Space Extraction 35 3.2.1.1 Subimage Mean 35 3.2.1.2 Subimage Variance 36 3.2.1.3 Subimage Entropy 36 3.2.1.4 Subimage Fractal Dimension 37 5 TABLE OF CONTENTS - Continued Page 3.2.2 Neural Network Classifier 41 3.2.2.1 Neural Network Overview 41 3.2.2.2 Neural Network Training 43 3.3 Bit Rates for ARIDPCM 44 3.4 Additional Algorithm Notes 45 3.5 Advantages 46 3.6 Disadvantages 47 4. SIMULATION RESULTS AND PERFORMANCE COMPARISONS 53 4.1 Neural Network Training Results 53 4.2 ARIDPCM and RIDPCM Performance Comparisons 55 4.2.1 Comparison Method 56 4.2.2 Test Results 58 5. CONCLUSIONS AND FUTURE WORK 84 LIST OF REFERENCES 86 6 USTOF FIGURES Figure Page 1.1 Block Diagram of IDPCM System 17 2.1 Block Diagram of RIDPCM System 27 2.2 Bilinear Kernels 28 2.3 Two Dimensional Representation of RIDPCM 29 2.4 Histogram of Subsample Values of Lenna 30 2.5 Histogram of First Set of Differences of Lenna 30 2.6 Histogram of Second Set of Differences of Lenna 31 2.7 Histogram of Third Set of Differences of Lenna 31 3.1 Block Diagram of ARIDPCM System 48 3.2 Blanket Covering Method for Estimating Fractal Dimension 49 3.3 Simple Processing Element 50 3.4 Sigmoidal Activation Function 50 3.5 Feedforward Network Configuration 51 3.6 Decision Regions as a Function of Network Configuration 52 4.1 Parity-3 Learning Curve 61 4.2 Original Lenna Image and Subimage Map 62 4.3 Histogram of Lenna 63 4.4 Training Data for Lenna 65 7 LIST OF FIGURES - Continued Figure Page 4.5 Learning Curve for Lenna 66 4.6 Class Label Map and Distribution-38 samples 67 4.7 Class Label Map and Distribution-113 samples 68 4.8 Approximate Quantization Bit Rates for Lenna: 6/4/4/4 69 4.9 Approximate Quantization Bit Rates for Lenna: 6/3/2/2 70 4.10 Approximate Quantization Bit Rates for Lenna: 6/3/2/1 71 4.11 Approximate Quantization Bit Rates for Lenna: 6/3/2/0 72 4.12 Approximate Quantization Bit Rates for Lenna: 6/1/1/1 74 4.13 Original Moon Image 75 4.14 Histogram of Moon 76 4.15 Class Label Map and Distribution for Moon 77 4.16 Approximate Quantization Bit Rates for Moon: 6/3/2/0 78 4.17 Approximate Quantization Bit Rates for Moon: 6/3/0/0 79 4.18 Original Rural Image 80 4.19 Histogram of Rural 81 4.20 Class Label Map and Distribution for Rural 82 4.21 Comparison of ARIDPCM and RIDPCM on Rural 83 8 LIST OF TABLES Table Page 2.1 Example of Equal Length, Natural Code Word Assignments 26 4.1 Parity-3 Training Data 61 4.2 ARIDPCM Subimage Class Labels 64 9 ABSTRACT Recursive Interpolated Differential Pulse Code Modulation (RIDPCM) is a fast and efficient method of digital image data compression. It is a simple algorithm which produces a high quality reconstructed image at a low bit rate. However, RIDPCM compresses the entire image the same regardless of image detail. This thesis introduces a variation on RIDPCM which adapts the bit rate according to the detail of the image. Adaptive RIDPCM (ARIDPCM) is accomplished by dividing the original image into smaller subimages and extracting features from them. These subimage features are passed through a trained neural network classifier. The output of the network is a class label which denotes the estimated subimage activity level or subimage type. Each class is assigned a specific bit rate and the subimage information is quantized accordingly. ARIDPCM produces a reconstructed image of higher quality than RIDPCM with the benefit of a further reduced bit rate. 10 CHAPTER 1 INTRODUCTION With the advent of sophisticated communication hardware and imaging systems, it is becoming increasingly more important to develop means of transmitting and storing the resulting massive amounts of data. This is the primary impetus of the image data compression field. There are two general categories of data compression, information preserving and non-information preserving [1]. Information preserving coding techniques retain all of the information of the original digital image. This allows the compressed image to be reconstructed into the exact original digital image. These coding techniques are used when the exact details of the image are required for further processing, such as fingerprint analysis. When some loss of image integrity is acceptable, the non-information preserving (lossy) techniques are much more efficient on storage space and transmission time.