## Dr Steve Sangwine

Version française## Brief biography

I am a Senior Lecturer at the University of Essex, working in the School of Computer Science and Electronic Engineering. At the time the School was created, I served as one of three Deputy Heads, firstly for Development in academic year 2007-8, including curriculum development and recruitment, and then Teaching in part of academic year 2008-9. I was on Research Leave in academic year 2009-10. From 2010 to 2012 I was Director of Undergraduate Studies. In 2012-13 and 2013-14 I was on Research Leave in the Spring Term (January-April 2013 and 2014). My research interests are in the theory and practice of signal and image processing with vector samples - typically colour images and 3-dimensional signal samples. This is achieved by working in hypercomplex algebras, mainly the quaternions and biquaternions. Since 2010 I've also been interested in the wider field of Clifford algebras, of which the quaternions are special case. The story of how I ended up working in this field is recounted below.

I was born in London in 1956 and have never lived more than about 100km away. Since my late school years I have been interested in electronics and I have spent my whole career working in electronics in one way or another, although my technical interests now are somewhat removed from circuits and electronic design, and in recent years I've become more oriented towards mathematics, publishing some papers in mathematical rather than engineering journals.

I studied Electronic Engineering at the University of Southampton graduating with a BSc in 1979. For the next five years I worked at the former Harwell Laboratory of the UKAEA which, at the time, was a much larger organization than it is now. After a short period working in commercial industry I joined the University of Reading in January 1985 as a Lecturer in the Department of Engineering. During my first six years at Reading I worked on my PhD in digital circuit test (fault diagnosis), graduating in 1991. I also wrote the first edition of

Electronic Components and Technology, which has since been through two further editions, in 1994 and in 2007 (see cover picture and full details on this page).In 1992 I started working on colour image processing, supervising my first research student, Dr Alan Pritchard, with Robin Horne as co-supervisor. I next supervised Dr Amy Thornton, then Dr Will Berriss and Dr Anthony Bardos. During this time I edited (with Robin Horne)

The Colour Image Processing Handbook(see details below), which was published in 1998. About this time, I first got interested in hypercomplex numbers and made contact with Dr Todd Ell in Minnesota, with whom I have worked since 1998. We've published quite a few papers together and advanced the theory and practice of colour image processing using hypercomplex filters and transforms.I left the University of Reading at the end of 2000, and joined the University of Essex working in the Department of Electronic Systems Engineering, one of the two departments that merged in 2007 to create the school I now work in.

Before leaving Reading, I obtained my first major research grant from the Engineering and Physical Sciences Research Council (EPSRC). Three researchers worked on this grant (Dr Carolyn Evans at Reading, and Dr Eddie Moxey and Dr Barnabas Gatsheni at Essex). You can see the papers we published in my publication list on this page. The idea of the work was to discover new colour image filters based on hypercomplex (quaternion) coefficients. This work has since been supported by two more grants from EPSRC, both to support the collaboration I have with Todd Ell.

In 2001, shortly after arriving at Essex, Dr Nicolas Le Bihan came to see me and told me about his work on signal processing using quaternion linear algebra. Nicolas and I have worked together since, and the collaboration was supported by a small grant from EPSRC. In 2005, with financial support from the Royal Academy of Engineering, and CNRS in France I was able to spend 7 months working as a Visiting Researcher (

Chercheur Invitéin French) at the Laboratoire des Images et des Signaux (now part of a larger lab called GIPSA), in Grenoble, working with Nicolas. We have published some papers together, and also developed a quaternion toolbox for Matlab (see below) which I now use also for the work with Todd Ell. Many of our algorithms and results are implemented in this toolbox, so anybody can try out the methods (well, not quite anybody, you have to know quite a bit about signal and image processing and mathematics). During my time in Grenoble, I worked also with Salem Said, a research student in the lab, supervised by Nicolas, and the three of us developed a complexified quaternion version of the quaternion transform earlier developed by Todd Ell and myself. We (Todd, myself, Nicolas, Salem) are still working on understanding the complexified quaternions - they are a form of geometric algebra, which suggests to us many possibilities in signal and image processing. From 2008 I also worked with Daniel Alfsmann at the Ruhr-Universität Bochum in Germany on aspects of hypercomplex algebras with application to signal processing, and we have published a paper setting out the details of biquaternion divisors of zero.During all this time, I have been teaching among other things, digital system design using VHDL, and I've supervised a couple of MSc projects and a PhD project in the area of network-on-chip. You can see what else I've taught in the listing below and also what I am teaching now.

## Publications

- Full list of publications also available as a PDF document. .
- Citations on Google Scholar.

- Author (with Todd Ell and Nicolas Le Bihan) of
Quaternion Fourier Transforms for Signal and Image Processing(ISTE-Wiley, May 2014, ISBN 978-1-84821-478-1).- Author of
Electronic Components and Technology(CRC Press, 3rd edition 2007, ISBN 0849374979)

This book was first published in 1987 and is still in print, now in its third edition.

- Editor (with R. E. N. Horne) of
The Colour Image Processing Handbook(Chapman and Hall, March 1998)- Editor (with Eckhard Hitzer) of
Quaternion and Clifford Fourier Transforms and Wavelets(Birkhauser, 2013)- Editor (with Muhammad Yasir Qadri) of
Multicore Technology: Architecture, Reconfiguration, and Modeling(CRC Press, 2013).## Teaching

I have taught a variety of material, including Digital Signal Processing, Digital System Design, Algorithms and Data Structures, Computer Systems, Circuit Theory, Microprocessor Architectures, Digital IC Design, Internet Computing, and Mathematics for Computing. My teaching duties for 2015-16 are:

- CE264 Digital Systems Design
- CE885 Mathematical Research Techniques with Matlab
## Resources

This section contains links to some offshoots of my work that are freely available. I support the open source software movement, and several of the items below are licensed under the GNU General Public Licence.

- QTFM Quaternion toolbox for Matlab®. Downloaded more than 10,000 times over 14 releases since 2005.
- Linear Quaternion Systems toolbox for Matlab®.
- Clifford Multivector Toolbox (for Matlab®).
- PNG_IO - An Ada 95 Portable Network Graphics library.
- FFTW_Ada - An Ada 95 binding to the FFTW Fast Fourier Transform library.
- QuaternionAlgebra - A Maple 8 package for symbolic algebra with quaternions.
- Colour test images
- RGB Colour cube net image
## Professional activities

President (2008-2010 and 2014-15) and Vice-President (2005-2008) Essex Local Association of the UCU (formerly AUT).

Member UCU National Executive Committee since 2010, serving on Education Committee (2010-2013 and 2014-2016), Legal Support Review Panel (2010-2013) and the National Council of the Teacher Support Network/Recourse (2011-).Formerly Honorary Secretary (1995-97) and President (1997-99), Reading Local Association AUT.

President (2007-2009) Staff Common Room Association, University of Essex.

## Technical Interests

I'm an enthusiast for Ada, and used it for research from 1986 until about 2006. I'm also an enthusiast for LaTeX which I have used on both Windows and Mac OS X platforms. I'm currently using TeXShop on an Apple MacBook Pro. I've typeset many journal and conference papers and several books, including authoring LaTeX style files. Since 2005 I have also been a keen user of Matlab (see above).## Leisure interests

I have been interested in railways since the age of 11. In 1994 I travelled on the Eurostar service very soon after it opened, and an account is available (now approaching 20 years old, but still getting read by many people interested in the Channel Tunnel).I am also interested in genealogy (with an unusual name like mine that is not surprising perhaps). For a bit more information, see here.

I've been a vegetarian for a long time, and a vegan since 2000.

## Studying with us

If you are interested in studying for a research degree with me, or one of my colleagues, please see the postgraduate research page on our website for information about how to apply. If you want to discuss a proposed area of research before submitting an application, contact me by email (below). You'll need to have good mathematical skills and ability to write experimental code to test out ideas. Please note that the School does not offer internships.## Contact details

Dr S. J. Sangwine

School of Computer Science and Electronic Engineering

University of Essex

Wivenhoe Park

Colchester CO4 3SQEmail: s j s (at) essex.ac.uk Telephone: 01206 872401 (direct dialling) Fax: 01206 872900 (departmental machine) Google: sz2xU7wAAAAJ ORCID : 0000-0002-4569-5630 SCOPUS: 7003346836 PGP: Public Key Fingerprint: E15C 974C 09CE E5AD 8E44 6A40 4186 115F 56B1 90ED Digital Signature: Certificate (for use with Adobe Reader) Serial number: 93 15 7B AE F2 4C 9E 8F C8 4F SHA1: 96 1B 11 51 3B FB C6 CA 6D 71 86 49 EF AD AA 44 D5 3A 10 95 MD5: C7 46 E8 49 17 EA E2 51 2F 05 46 7D 8A A2 6A D7

Created: 24 January 2001

Updated: 25 August 2015

To: School of Computer Science and Electronic Engineering

To: University of Essex