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OUTLINE OF THE UPCOMING BOOK...
Chapters currently available for free download in PDF format indicated by asterisk (*)
- CHAPTER 1* - Preview of Wavelets, Wavelet Filters and Wavelet Transforms in Digital Signal Processing (DSP)
What is a Wavelet?
What is a Wavelet Filter and how is it Different from a Wavelet?
The Value of Transforms and Examples of Everyday Use
Short-Time Transforms, Sheet Music, and a First Look at Wavelet Transforms
An Example of the Fast Fourier Transform (FFT) with an Embedded Pulse Signal
Examples Using the Continuous Wavelet Transform
A First Glance at the Undecimated Discrete Wavelet Transform (UDWT)
Why the UDWT is Sometimes Called a “Redundant” DWT (RDWT) or “A’ Trous” (“with holes”)
A First Glance at the Conventional Discrete Wavelet Transform (DWT)
Examples of Use of the Conventional DWT
Summary
- CHAPTER 2* - Walk-Through of the Continuous Wavelet Transform (CWT) using the Haar Wavelet Filters
Simple Scenario: Comparing Exam Scores Using the Haar Wavelet
Above Comparison Process Seen as Simple Correlation or Convolution
Display of the Continuous Wavelet Transform (CWT) of the Exam Scores Using the Haar Wavelet Filter
Summary
- CHAPTER 3* - Walk-Through of the Undecimated Discrete Wavelet Transform (UDWT) using the Haar Wavelet Filters
Single-Level UDWT of Exam Data
Frequency Allocation of a Single-Level UDWT
Multi-Level UDWT
Frequency Allocation of a Multi-Level UDWT
The Haar UDWT as a Moving Averager
Summary
- CHAPTER 4* - Walk-Through of the Conventional (Decimated) Discrete Wavelet Transform (DWT) using the Haar Wavelet Filters
Single-Level (Decimated/Downsampled) Discrete Wavelet Transform (DWT) of Exam Data
Additional Example of Perfect Reconstruction in a Single-Level DWT
Compression and Denoising Example using the Single-Level DWT
Multi-Level Conventional (Decimated) Discrete Wavelet Transform (DWT) of Exam Data using Haar Wavelet Filters
Frequency Allocation in a (Conventional, Decimated) DWT
Final Approximations and Details and How to Read the DWT Display
Denoising Using a Multi-Level DWT
Summary
- CHAPTER 5 - Filters from WaveletsObtaining Real-World Discrete Filters from Wavelets with Explicit Mathematical Expressions (“Crude Wavelets”)
Review of Familiar DSP Truncated Sinc Function
Adding More Points at the Ends for Better Filter Performance
Adding More Points by Interpolation for Lower Cutoff Frequency
Multi- Point “Stretched Filters” Derived from Explicit Mathematical Equations of “Crude” Wavelets
Mexican Hat Wavelet and Morlet Wavelet as Examples of Stretched Filters
How the Passband is Changed due to Stretching
CWT Display of the Results of Using these Stretched Filters on a Split-Sine Test Signal
Summary
- CHAPTER 6 - Wavelets from FiltersFixed Length Filters to Continuous Wavelet Estimation to Variable Length Filters
Interpolation of Original Wavelet Filter by Upsampling and LowPass Filtering
Building an Estimation (Approximation) of a “Continuos” Wavelet Function
Building a Filter of Any Desired Length from the “Continuous” Estimation
Example of Building a 258-Point “Continuous” Haar Wavelet Function from the 2-Point Filter
Building a Haar Filter of Arbitrary Length from the 258 Point Estimation
Numerical Integration to Handle the Discontinuities in the Haar
Frequency Response of the Original and Stretched Haar Filters
Haar and Shannon Wavelet Filters as “Duals” of Time/Frequency Precision
Example of Building a 768-Point “Continuous” Daubechies 4 (Db4) Wavelet Function from the 4-Point Filter
Building a Db4 Wavelet Function Filter of Arbitrary Length from the 768 Points
Perfect Overlay of Four Equispaced Db4 Filter Points on the “Continuous” Wavelet Estimation
Two Additional Equispaced Zero Points (at the end) Complete the Overlay
Physical Meaning of the “Length” of a Wavelet
Frequency Response of the Original and Stretched Db4 Wavelet Function Filters
Perfect Overlay of the Db6, Db8, Coiflet, and Biorthogonal Filter Points and Zero Points on their Estimations
Summary
- CHAPTER 7 - Overview and Comparison of the Four Major Types of Wavelet Transforms
Advantages and Disadvantages of the Continuous Wavelet Transform (CWT)
Stretching the WaveletThe Undecimated Discrete Wavelet Transform (UDWT)
Shrinking the Signal InsteadThe Conventional (Downsampled) Discrete Wavelet Transform (DWT)
Decomposing More of the SignalThe Wavelet Packet Transform (WPT)
The Problem of Aliasing Caused by Downsampling in the WPT and the Conventional DWT
How to Cancel Out the Aliasing If Done Correctly
Summary
- CHAPTER 8 - Perfect Reconstruction Quadrature Mirror Filters (PRQMF) and their Relationships
The Four PRQMF FiltersHighPass (HP) Decomposition, HP Reconstruction, LowPass (LP) Decomposition and LP Reconstruction
Close Relationships of the Four PRQMF Filters to Each Other
Building the Wavelet Function from the HP Reconstruction Filter
Building the Scaling Function from the LP Reconstruction Filter
Summary
- CHAPTER 9 - Another Look at the DWT and UDWT DisplaysImportant Relationships
DWT and UDWT Displays of a Split Sine Signal with the Db4 Scaling Function
DWT and UDWT Displays of a Split Sine Signal with the Db4 Wavelet Function
DWT and UDWT Displays of a Decaying Exponential Signal with the Haar Scaling Function.
DWT and UDWT Displays of a Decaying Exponential Signal with the Haar Wavelet Function
Summary
- CHAPTER 10 - Reconciling the DWT and UDWT to the CWTAll are Basic Correlations
Locations on the Signal Diagram where the UDWT and the CWT are Exactly the Same Using Haar Wavelet Filters
Locations on the Signal Diagram where the Conventional DWT and the CWT are the Same When Downsampled Using Haar Wavelet Filters
Locations on the Signal Diagram where the Conventional DWT and the CWT are Very Similar Using Four-Point Db4 Filters
Summary
- CHAPTER 11 - Looking at the Major Wavelet FamiliesTheir Strengths, Weaknesses, and Popular Uses
Vanishing Moments
Time vs. Frequency Resolution
Orthogonality
Symmetry
Suitability for use in a DWT or UDWT
Table of Desired Properties and Best Choice of Wavelet
The “Sport of Basis Hunting” and Best Basis
The Lifting Scheme
Summary
- CHAPTER 12 - Case studies of Applications of Wavelets to Real-Life Problems
Removing White Noise Using the CWT
Extracting a Weak Binary QPSK Signal from 80 dB of Noise Using Time-Dependant Thresholding
Noise Identification Using the CWT and the DWT
Compression of Images Using a 2-D DWT with the Biorthogonal Wavelet
JPEG Compression Using Wavelets
Example showing Superior Denoising Capability Using the UDWT
Summary
- CHAPTER 13 - Building the Scaling Function (phi) using the PRQMF Filters and the Dilation Equation
Review of Building Wavelet Function (Estimation) Using Wavelet Filter Points at Known Locations to Produce Additional Points
Building Scaling Function (Estimation) Using Scaling Function Filter Points at Known Locations
Repeated Upsampling and Filtering to Produce Multi-Point Estimation of a “Continuous” Scaling Function
Overlaying Original Scaling Function Filter Points on the “Continuous” Scaling Function Estimation for Perfect Fit
Historical Perspective of Roman Numerals, Negative and Irrational Numbers, Imaginary Numbers, etc.
The 2-Scale Difference Equation and the Scaling Function Dilation Equation
Relating the Scaling Function Dilation Equation to the Conventional Discrete Wavelet Transform
Recursive Wavelet Processing as a “Child of the Digital Age”
Summary
- CHAPTER 14 - Building the Scaling Function (phi) using the Perfect Reconstruction Quadrature Mirror Filters and Simple Convolution
Replication of the Dilation Equation by Dyadic Upsampling and Convolution
The Scaling Function is Built from the Filters, not the Other Way Around
Upsampling and Filtering can be Observed in DWT Signal Flow ChartsMiniature Scaling Function Replicas Seen as a Result
Summary
- CHAPTER 15 - Building the Wavelet Function (psi) from Both the Dilation Equation and by Simple Convolution
Wavelet Function Dilation Equation uses BOTH Scaling Function AND Wavelet Function Basic Filter Points (LowPass and HighPass) to Produce Additional Points
Other Similarities and Differences to the Scaling Function Dilation Equation
Another Look at Repeated Upsampling and Filtering to Build the Multi-Point “Continuous” Wavelet Estimation
Upsampling and Filtering can be Observed in DWT Signal Flow Charts
Miniature Wavelet (Function) Replicas Also Observed as Artifacts from Repeated Upsampling and Filtering in Signal Diagrams.
Summary
- CHAPTER 16 - Perfect Reconstruction Begins with the HalfBand Filters
A First Look at the HalfBand (HB) Filters
HighPass HB Filter Factored into Wavelet Decomposition and Reconstruction Filters
LowPass HB Filter Factored into Scaling Function Decomposition and Reconstruction Filters
HB Filters in the Simple Undecimated Discrete Wavelet Transform
HB Filters in the Conventional (Downsampled) Discrete Wavelet Transform
Summary
- CHAPTER 17 - Alias Cancellation Demonstrated in the Time Domain
Step-By-Step Look at Convolution (Filtering) on both the HP and LP Paths of a DWT
Cancellation of HP and LP Terms Except When They Align
Perfect Reconstruction to Within a Delay and a Constant of Multiplication
Linear Time Invariant (LTI) Properties of the DWT
Signal Flow Diagrams of the LTI DWT to Extract Needed Approximations and Details
Summary
- CHAPTER 18 - Alias Cancellation Demonstrated in the Frequency Domain
Filtering of the Signal in the DWT by the Decomposition Filters
Downsampling the Result Which Can Cause Aliasing
Equivalence of Downsampling to “Sliding” Higher Frequencies to the Left
Upsampling Now Causes Imaging or “Unfolding” of Frequencies
Complex Addition of HP and LP Paths
Alias Cancellation on Because Same Magnitude but Opposite Phase from the HP and LP Paths
Signal Reconstruction Because In Phase Components from the HP and LP Paths
Summary
- CHAPTER 19 - Relating Alias Cancellation Concepts to Equations Found in Traditional Literature
Paraunitary Conditions
“No-Distortion” Equations and In-Phase Addition
Alias Cancellation Equations and Out-Of-Phase Cancellations
Summary
- CHAPTER 20 - Creating “Fake” Wavelets
Appreciating the Elegant Properties of the Classic Wavelets
Single Cycle of a Sine Wave as a “Crude” Fake Wavelet
CWT Display Comparison Using Haar and Db4 Wavelets
Using a GPS Signal as a “Fake Wavelet” in a CWT to Account for Doppler, Slew, and Chirp
Truncated Db4 Wavelet FiltersValid HalfBand Filters but Fewer Vanishing Moments
Vanishing Moments Revisited
Summary
- CHAPTER 21 - Deriving the “Magic Numbers” of the Wavelet Filters from the Desired Capabilities
Vanishing Moments Properties
Desired Orthogonality Properties
Wavelet Filter Values Sum to Zero
Squares of Wavelet Filter Values Sum to Unity (Unit Energy)
Simple Substitution to Produce the “Magic Numbers” for all Four Basic Wavelet Filters
Summary
- CHAPTER 22 - Trading Pure Orthogonality for “Biorthogonality”, Symmetry, and Linear Phase
Another Way to Factor the HalfBand Filters
Decomposition and Reconstruction Filters with Different Lengths
Symmetry and Linear Phase
Comparing Db4 Filters (4 Points Each) with BIOR 3/5 Filters (3 or 5 Points Each)
Limited Orthogonality or “Bi”-Orthogonality
Use of the BIOR 7/9 Filters for JPEG and FBI Fingerprint Compression
Summary
- CHAPTER 23 - The Undecimated Discrete Wavelet Transform (UDWT) Revisited
Extra Storage and Computational Burden vs. Alias-Free Processing
Stretching the Filters Correctly in Octaves of Frequency
Comparison of UDWT and Conventional DWT Displays
Pathological Noise Cases Which Favor the use of the UDWT
The UDWT as Sanity Check for the DWT
Hybrid Methods using Both UDWT and DWT
Summary
- APPENDICES
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