Seeing with sound - Blast from the past

In a recent restructuring at the University of Northampton both the areas of Computing and Engineering joined the larger Faculty of Arts, Science and Technology (FAST). This is not the first time though that the computing technology has used by members the University's computing or engineering staff to provide social benefit, but with links to areas of visual and audio creativity .

In June 2000 Michael Capp, under the supervision of Professors Phil Picton and Jackie Campbell, completed his PhD  "Alternatives Approaches to Optophonic Mappings" 

Abstract
This thesis presents a number of modifications to a blind aid, known as the video optophone, which enables a blind user to more readily interpret their local environment for enhanced mobility and navigation. Versions o f this form of blind aid are generally both difficult to use and interpret, and are therefore inadequate for safe mobility. The reason for this severe problem lies in the complexity and excessive bandwidth of the optophonic output after the conversion from scene-to-sound. 

The work herein describes a number of modifications that can be applied to the current optophonic process to make more efficient use of the limited bandwidth provided by the auditory system when converting scene images to sound. Various image processing and stereo techniques have been employed to artificially emulate the human visual system through the use o f depth maps that successfully fade out the quantity o f relatively unimportant image features, whilst emphasising the more significant regions such as nearby obstacles. 

A series of experiments were designed to test these various modifications to the optophonic mapping by studying important factors of mobility and subject response whilst going about everyday life. The devised system, labelled DeLIA for the Detection, Location, Identification, and Avoidance (or Action) of obstacles, provided a means for gathering statistical data on users’ interpretation of the optophonic output. An analysis o f this data demonstrated a significant improvement when using the stereo cartooning technique, developed as part of this work, over the more conventional plain image as an input to an optophonic mapping from scene-to-sound. Lastly, conclusions were drawn from the results, which indicated that the use of a stereo depth map as an input to a video optophone would improve its usefulness as an aid to general mobility. For the purposes of detecting and determining text or similar detail, either a plain unmodified image or some form of edge (depth) image were found to produce the best results.

Published Outputs
[CapPicOOa] - Capp, M. and Picton, P., (Feb.-Mar. 2000). ‘Fast, Low Resolution Edge Depth Maps and their Application to a Blind Mobility Aid’, International Conference on Computer Vision, Pattern Recognition and Image Processing, Atlantic City, USA, C V P R IP -12, pp. 248-251. 
[CapPicOOb] - Capp, M., & Picton, P., (Jun. 2000). “The Optophone: an Electronic Blind Aid.” Engineering Science and Education Journal, vol. 9, no. 3, pp. 137-143. 
[CapPicOOc] - Capp, M. & Picton, P., (Aug. 2000). ‘An investigation into stereo vision as a modification to optophonic mappings from scene-to-sound.’ l0th International Mobility Conference, Warwick, 4th-7th Aug. 2000. 
[CapPicOOd] - Capp, M. & Picton, P., ‘Relaying Scene Information to the Blind via Sound using Cartoon Depth Maps.’ - Vision, Image and Signal Processing, 2000.




To find out more contact Phil Picton phil.picton@northampton.ac.uk


All views and opinions are the author's and do not necessarily reflected those of any organisation they are associated with. Twitter: @scottturneruon

evoked potentials, wavelets and evolutionary algorithms

Extraction of short-latency evoked potentials using a combination of wavelets and evolutionary algorithms

S Turner 

P Picton, 

J Campbell

Medical Engineering and Physics

Volume 25, Issue 5, J, Pages 407–412

Available at: http://www.sciencedirect.com/science/article/pii/S1350453303000213

Abstract

Somatosensory evoked potentials, recorded at the spine or scalp of a patient, are contaminated by noise. It is common practice to use ensemble averaging to remove the noise, which usually requires a large number of responses to produce one averaged signal. In this paper a post-processing technique is shown which uses a combination of wavelets and evolutionary algorithms to produce a representative waveform with fewer responses. The most suitable wavelets and a set of weights are selected by an evolutionary algorithm to form a filter bank, which enhances the extraction of evoked potentials from noisy recordings.

Selecting Potentials Filter Banks to Enhance Evoked Recordings Using Evolutionary Algorithms

S. J. Turner, P. D. Picton and J. A. Campbell

Abstract

Evoked Potentials are electrical Signals produced by the body in response to a Stimulus. In general these Signals are noisy with a low Signal to noise ratio. In this Paper a method is proposed that uses sets of filters, whose tut-off frequencies are selected by an evolutionary algorithm. An evolutionary algorithm was investigated to limit the assumptions that were made about the Signals. The set of filters separately filter the evoked Potentials, and are combined as a weighted sum of the filter Outputs. The evolutionary algorithm also selects the weights. Inputs to the filters are sets of averaged Signal, 4 or 10 Signals per average. Even though there is likely to be variations between the Signals, this process tan improve the extraction of Potentials.

Paper is available: http://www.springerlink.com/content/t107316042353960/

Computational Model of Acute Pain

A Computational Model of Acute Pain 
Karen Prince, Jackie Campbell, Phil Picton, Scott Turner 

Paper available at: http://ducati.doc.ntu.ac.uk/uksim/journal/Vol-6/No.9/Paper1.pdf


Abstract: In 1965 Melzack and Wall proposed the influential gate control theory of pain.  This theory postulates that the substantia gelatinosa, located within the spinal cord, acts like a gating mechanism, which modulates the flow of information through the spinal cord to the brain and thus impacts on the pain experience. Subsequent research has, in general, supported this theory.  The explicitness of the theory and its well-defined architecture was translated into a mathematical model by Britton and Skevington in 1996.  However, the use of such modelling has been very limited in the field of pain.  

The fact that pain is still relatively a poorly understood phenomenon despite the abundance of literature that is available and because of the difficulty in obtaining some experimental data, suggest that it is an ideal candidate for mathematical modelling.  This paper successfully replicates the mathematical model as presented by Britton and Skevington.  It uses this as a platform to develop the model further to test some of the assumptions made in its original development and, more importantly, to produce a more biologically plausible model that can be used for further applications. 

Paper available at: http://ducati.doc.ntu.ac.uk/uksim/journal/Vol-6/No.9/Paper1.pdf