Network accessible parallel computing systems, based upon transputers, for image processing strategies
Over the last decade there has been a steady increase in the size of primary data sets collected from medical imaging devices, and a correspondingly increased requirement for the computational power needed for associated image processing techniques. Although conventional processors have shown considerable advances throughout this period, they have failed to keep pace with the demands placed upon them by clinicians keen to utilise techniques such as pseudo three dimensional volume image presentation and high speed dynamic display of multiple frames of data. One solution that has the capability to meet these needs is to use multiple processors, co-operating to solve specified tasks using parallel processing. This thesis, which reports work undertaken during the period 1988-1991, shows how a network accessible parallel computing resource can provide an effective solution to these classes of problems. Starting from the premise that any generally accessible array of processors has to be connected to the inter-computer communication network, an Ethernet node was designed and constructed using the Inmos transputer. With this it was possible to demonstrate the benefits of parallel processing. Particular emphasis had to be given to those elements of the software which must make a guaranteed real-time response to external stimuli and it is shown that by isolating high priority processes, relatively simple OCCAM code can satisfy this need. Parallel processing principles have been utilised by the communications software that implemented the upper layers of the OSI seven layer network reference model using the Internet suite of protocols. By developing an abstract high level language, software was developed which allowed users to specify the inter-processor connection topology of a point to point connected multi-transputer array, built in association with this work. After constructing a flexible, memory efficient, graphics library, a technique to allow the high speed zooming of byte sized pixel data using a lookup table technique was developed. By using a multi-transputer design this allowed a 128x128 pixel image to be displayed at 256x256 pixel resolution at up to 25 frames per second, a requirement imposed by a contemporary cardiac imaging project.