2020 applicants
People

Dr Stephen Sangwine

Senior Lecturer
School of Computer Science and Electronic Engineering (CSEE)
Dr Stephen Sangwine
  • Email

  • Location

    3A.526, Colchester Campus

  • Academic support hours

    Wednesdays 11:00-12:00 913 6726 5308

Profile

Biography

I've worked at Essex since 2001, and I've been an academic since 1985. I was originally an electronics engineer, but now my research interests make me more of a computer scientist and mathematician. For a more detailed biography see my personal web pages (link below). (See also:staff research interests by category)

Qualifications

  • PhD University of Reading, (1991)

  • BSc (Hons) Electronic Engineering University of Southampton, (1979)

Research and professional activities

Research interests

Colour image processing and vector signal processing

Open to supervise

Hypercomplex linear algebra and matrix decompositions with applications to vector signal and image processing

Open to supervise

Hypercomplex Fourier transforms and filters, vector filtering, filtering of orientation signals

Open to supervise

Current research

I completed a book in 2014 about Quaternion Fourier Transforms in Signal and Image Processing with Dr Todd Ell in Minnesota, and Dr Nicolas Le Bihan in Grenoble.

I'm also working on Clifford algebras with Dr Eckhard Hitzer at ICU in Tokyo, with whom I have developed a Clifford algebra toolbox for Matlab, and with Todd and Dr Hendrik de Bie in Gent, Belgium, on the mathematics of hypercomplex Fourier transforms and convolution formulae.

Teaching and supervision

Current teaching responsibilities

  • Digital Systems Design (CE264)

  • Electronic System Design and Integration (CE721)

Previous supervision

Peter Fletcher
Peter Fletcher
Thesis title: Hypercomplex Scaling and Wavelet Filters: Their Discovery and Their Application to Colour Vector Image Processing
Degree subject: Computing and Electronic Systems
Degree type: Doctor of Philosophy
Awarded date: 5/7/2019
Shagufta Yasmin
Shagufta Yasmin
Thesis title: Linear Colour Image Processing in Hypercomplex Algebra Guided By Genetic Algorithms
Degree subject: Electronic Systems Engineering
Degree type: Doctor of Philosophy
Awarded date: 18/1/2019

Publications

Journal articles (36)

Sangwine, SJ. and Hitzer, E., (2020). Polar decomposition of complexified quaternions and octonions. Advances in Applied Clifford Algebras. 30 (2)

Hitzer, E. and Sangwine, S., (2019). Construction of multivector inverse for Clifford algebras over 2m+1-dimensional vector spaces from multivector inverse for Clifford algebras over 2m-dimensional vector spaces. Advances in Applied Clifford Algebras. 29 (2)

Hitzer, E. and Sangwine, S., (2019). Foundations of Conic Conformal Geometric Algebra and Compact Versors for Rotation, Translation and Scaling. Advances in Applied Clifford Algebras. 29 (5)

Yasmin, S. and Sangwine, SJ., (2018). Multi-directional colour edge detector using linear quaternion system convolution. IET Image Processing. 12 (7), 1111-1116

Sangwine, SJ., (2017). On harmonic analysis of vector-valued signals. Mathematical Methods in the Applied Sciences. 40 (1), 22-30

Fletcher, P. and Sangwine, SJ., (2017). The development of the quaternion wavelet transform. Signal Processing. 136, 2-15

Hitzer, E. and Sangwine, S., (2017). Multivector and multivector matrix inverses in real Clifford algebras. Applied Mathematics and Computation. 311, 375-389

Sangwine, SJ. and Hitzer, E., (2017). Clifford Multivector Toolbox (for MATLAB). Advances in Applied Clifford Algebras. 27 (1), 539-558

Sangwine, SJ., (2015). Comments on ‘A structure-preserving method for the quaternion LU decomposition in quaternionic quantum theory’ by Minghui Wang and Wenhao Ma. Computer Physics Communications. 188, 128-130

De Bie, H., De Schepper, N., Ell, TA., Rubrecht, K. and Sangwine, SJ., (2015). Connecting spatial and frequency domains for the quaternion Fourier transform. Applied Mathematics and Computation. 271, 581-593

Le Bihan, N., Sangwine, SJ. and Ell, TA., (2014). Instantaneous frequency and amplitude of orthocomplex modulated signals based on quaternion Fourier transform. Signal Processing. 94 (1), 308-318

(2013). Quaternion and Clifford Fourier Transforms and Wavelets. Quaternion and Clifford Fourier Transforms and Wavelets. abs/1306.2157, 1-338

Sangwine, SJ. and Ell, TA., (2012). Complex and hypercomplex discrete Fourier transforms based on matrix exponential form of Euler’s formula. Applied Mathematics and Computation. 219 (2), 644-655

Sangwine, SJ., Ell, TA. and Le Bihan, N., (2011). Fundamental Representations and Algebraic Properties of Biquaternions or Complexified Quaternions. Advances in Applied Clifford Algebras. 21 (3), 607-636

Sangwine, SJ. and Bihan, NL., (2010). Quaternion Polar Representation with a Complex Modulus and Complex Argument Inspired by the Cayley-Dickson Form. Advances in Applied Clifford Algebras. 20 (1), 111-120

Sangwine, SJ. and Alfsmann, D., (2010). Determination of the Biquaternion Divisors of Zero, Including the Idempotents and Nilpotents. Advances in Applied Clifford Algebras. 20 (2), 401-410

Said, S., Le Bihan, N. and Sangwine, SJ., (2008). Fast Complexified Quaternion Fourier Transform. IEEE Transactions on Signal Processing. 56 (4), 1522-1531

Ell, TA. and Sangwine, SJ., (2007). Hypercomplex Fourier Transforms of Color Images. IEEE Transactions on Image Processing. 16 (1), 22-35

Ell, TA. and Sangwine, SJ., (2007). Quaternion involutions and anti-involutions. Computers & Mathematics with Applications. 53 (1), 137-143

Le Bihan, N. and Sangwine, SJ., (2007). Jacobi method for quaternion matrix singular value decomposition. Applied Mathematics and Computation. 187 (2), 1265-1271

Sangwine, SJ., (2006). Biquaternion (Complexified Quaternion) Roots of −1. Advances in Applied Clifford Algebras. 16 (1), 63-68

Sangwine, SJ. and Le Bihan, N., (2006). Quaternion singular value decomposition based on bidiagonalization to a real or complex matrix using quaternion Householder transformations. Applied Mathematics and Computation. 182 (1), 727-738

Moxey, CE., Sangwine, SJ. and Ell, TA., (2003). Hypercomplex correlation techniques for vector images. IEEE Transactions on Signal Processing. 51 (7), 1941-1953

Sangwine, SJ., Eli, TA. and Moxey, CE., (2001). Vector phase correlation. Electronics Letters. 37 (25), 1513-1513

Sangwine, SJ., (2000). Colour in image processing. Electronics & Communication Engineering Journal. 12 (5), 211-219

Sangwine, SJ. and Ell, TA., (2000). Colour image filters based on hypercomplex convolution. IEE Proceedings - Vision, Image, and Signal Processing. 147 (2), 89-89

Bardos, AJ. and Sangwine, SJ., (1998). Measuring noise in colour images. IEE Colloquium (Digest) (284)

Sangwine, SJ., (1998). Colour image edge detector based on quaternion convolution. Electronics Letters. 34 (10), 969-969

Berriss, WP. and Sangwine, SJ., (1997). Automatic quantitative analysis of healing skin wounds using colour digital image processing. World Wide Wounds. 1997

Sangwine, SJ., (1996). Fourier transforms of colour images using quaternion or hypercomplex, numbers. Electronics Letters. 32 (21), 1979-1979

Sangwine, SJ., (1995). Experiences with High-Level Design and Modelling of Digital Systems. International Journal of Electrical Engineering Education. 32 (4), 333-340

Sangwine, SJ., (1995). A Digital Signal Processing Laboratory Based on the TMS320C25. International Journal of Electrical Engineering Education. 32 (1), 21-30

Pritchard, AJ., Horne, REN. and Sangwine, SJ., (1994). Rational arithmetic representation of colour image pixels. Electronics Letters. 30 (18), 1474-1475

Sangwine, SJ., (1992). Diagnosis of multiple faults in combinational digital circuits by modelling of transition propagation along critical paths. IEE Proceedings G Circuits, Devices and Systems. 139 (5), 594-594

Sangwine, SJ., (1989). Deductive fault diagnosis in digital circuits: a survey. IEE Proceedings E Computers and Digital Techniques. 136 (6), 496-496

Sangwine, SJ., (1988). Fault diagnosis in combinational digital circuits using a backtrack algorithm to generate fault location hypotheses. IEE Proceedings G (Electronic Circuits and Systems). 135 (6), 247-247

Books (5)

Ell, TA., Bihan, NL. and Sangwine, SJ., (2014). Quaternion Fourier Transforms for Signal and Image Processing. John Wiley & Sons, Inc.. 9781848214781

Qadri, MY. and Sangwine, SJ., (2013). Multicore Technology: Architecture, Reconfiguration, and Modeling. CRC Press. 9781439880630

Hitzer, E. and Sangwine, SJ., (2013). Quaternion and Clifford Fourier Transforms and Wavelets. Springer. 978-3-0348-0602-2

(1998). The Colour Image Processing Handbook. Springer US. 9781461376477

Sangwine, SJ., (1994). Electronic Components and Technology. Springer US. 9780412557002

Book chapters (5)

Sangwine, SJ., (2013). Perspectives on Color Image Processing by Linear Vector Methods Using Projective Geometric Transformations. In: Advances in Imaging and Electron Physics. Elsevier. 283- 307. 9780124076709

Hitzer, E. and Sangwine, SJ., (2013). The Orthogonal 2D Planes Split of Quaternions and Steerable Quaternion Fourier Transformations. In: Quaternion and Clifford Fourier Transforms and Wavelets. Springer Basel. 15- 39. 9783034806022

Sangwine, SJ., Ell, TA. and Le Bihan, N., (2009). Hypercomplex models and processing of vector images. In: Multivariate Image Processing. Editors: Chanussot, J., Collet, C. and Chehdi, K., . ISTE/Wiley. 407- 436. 978-1-84821-139-1

Sangwine, SJ. and Horne, REN., (1998). The present state and the future of colour image processing. In: The Colour Image Processing Handbook. Springer US. 1- 3. 9781461376477

Sangwine, SJ. and Thornton, AL., (1998). Frequency domain methods. In: The Colour Image Processing Handbook. Springer US. 228- 241. 9781461376477

Conferences (39)

Yasmin, S. and Sangwine, SJ., (2017). Quaternion linear colour edge-sharpening filter using genetic algorithm

Yasmin, S. and Sangwine, SJ., (2016). Quaternion Linear Color Edge-Glowing Filter Using Genetic Algorithm

Sangwine, SJ., Ell, TA. and Gatsheni, BN., (2015). Colour-dependent linear vector image filtering

Bihan, NL. and Sangwine, SJ., (2013). Quaternionic Spectral Analysis of Non-Stationary Improper Complex Signals

Hitzer, E. and Sangwine, SJ., (2013). Preface

SAID, S., Bihan, NL. and Sangwine, SJ., (2009). A Stability Approach to The Analysis of Rotation Time Series

Le Bihan, N. and Sangwine, SJ., (2008). The ℍ-analytic signal

Ell, TA. and Sangwine, SJ., (2008). Projective-space colour filters using quaternion algebra

Ell, TA. and Sangwine, SJ., (2008). Theory of vector filters based on linear quaternion functions

Said, S., Courty, N., Le Bihan, N. and Sangwine, SJ., (2007). Exact principal geodesic analysis for data on SO(3)

Alfsmann, D., Göckler, HG., Sangwine, SJ. and Ell, TA., (2007). Hypercomplex algebras in digital signal processing: Benefits and drawbacks

Sangwine, SJ. and Le Bihan, N., (2007). Hypercomplex analytic signals: Extension of the analytic signal concept to complex signals

Sangwine, SJ. and Ell, TA., (2004). Gray-centered RGB color space

Sangwine, SJ., Gatsheni, BN. and Ell, TA., (2003). Vector amplification for color-dependent image filtering

Le Bihan, N. and Sangwine, SJ., (2003). Quaternion principal component analysis of color images

Moxey, CE., Sangwine, SJ. and Ell, TA., (2002). Color-grayscale image registration using hypercomplex phase correlation

Sangwine, SJ. and Ell, TA., (2002). Vector zone plates as test patterns for linear vector filters

Sangwine, SJ. and Ell, TA., (2002). Mathematical Approaches to Linear Vector Filtering of Color Images

Moxey, CE., Ell, TA. and Sangwine, SJ., (2002). Vector Correlation of Color Images

Sangwine, SJ., Gatsheni, BN. and Ell, TA., (2002). Linear colour-dependent image filtering based on vector decomposition

Moxey, CE., Ell, TA. and Sangwine, SJ., (2002). Hypercomplex operators and vector correlation

Sangwine, SJ. and Ell, TA., (2001). Hypercomplex Fourier transforms of color images

Ell, TA. and Sangwine, SJ., (2000). Hypercomplex Wiener-Khintchine theorem with application to color image correlation

Bardos, AJ. and Sangwine, SJ., (2000). Virtual reality tool for visualising RGB colour space using VRML

Ell, TA. and Sangwine, SJ., (2000). Decomposition of 2D Hypercomplex Fourier transforms into pairs of complex fourier transforms

Evans, CJ., Sangwine, SJ. and Ell, TA., (2000). Colour-sensitive edge detection using hypercomplex filters

Evans, CJ., Sangwine, SJ. and Ell, TA., (2000). Hypercomplex color-sensitive smoothing filters

Sangwine, SJ. and Ell, TA., (1999). Hypercomplex auto- and cross-correlation of color images

Sangwine, SJ., (1998). The problem of defining the Fourier transform of a colour image

Bardos, AJ. and Sangwine, SJ., (1998). Measuring noise in colour images

Sangwine, SJ., (1997). The discrete quaternion Fourier transform

Berriss, WP. and Sangwine, SJ., (1997). Colour histogram clustering technique for tissue analysis of healing skin wounds

Thornton, AL., (1997). Log-polar sampling incorporating a novel spatially variant filter to improve object recognition

Bardos, AJ., (1997). Selective vector median filtering of colour images

Thornton, A., (1995). Colour object location using complex coding in the frequency domain

Pritchard, AJ., (1995). Achieving brightness-insensitive measurements of colour saturation for use in object recognition

Sangwine, SJ., (1995). Colour image thresholding at pixel rate using rational arithmetic hardware

Sangwine, SJ., (1995). Why hands-on and why real signals?

Sangwine, SJ. and Whitehouse, JE., (1994). Sampling theorem - a tutorial

Reports and Papers (5)

Bihan, NL. and Sangwine, SJ., The hyperanalytic signal

Sangwine, S. and Hitzer, E., (2019). Polar decomposition of complexified quaternions and octonions

Hitzer, E. and Sangwine, SJ., (2016). Multivector and multivector matrix inverses in real Clifford algebras

Sangwine, SJ., (2015). Octonion associators

Sangwine, SJ., (2008). Canonic form of linear quaternion functions

Other (1)

Sangwine, SJ., (2014).On harmonic analysis of vector-valued signals,arXiv.org

Grants and funding

2014

Research Visit to the International Christian University Tokyo

London Mathematical Society

2010

Hyperanalytic Signals & Vector Signal Processing Int Travel Grant

The Royal Society

Contact

sjs@essex.ac.uk

Location:

3A.526, Colchester Campus

Academic support hours:

Wednesdays 11:00-12:00 913 6726 5308