Publications

'Towards a complete model of photopic visual threshold performance'.

This is a major open publication extending what was covered in the book 'Vision and Acquisition'. It was published in Volume 21, No. 1 of the Journal 'Optical Engineering' (1982). Some idea of the contents should be obtained from the Summary of the paper, which is reproduced to the right.

Summary. Based on a wide variety of fragmentary evidence taken from psychophysics, neuro-physiology and electron microscopy, it has been possible to put together a very widely applicable conceptual model of photopic visual threshold performance. Such a model is so complex that a single comprehensive mathematical version is excessively cumbersome for general usage. It has, however, been possible to set up a suite of related mathematical models all based on the overall model, each of limited application but strictly known envelope of usage. Such models may be used for assessment of a variety of facets of visual performance when using display imagery, including effects & interactions of image quality, random & discrete display noise, viewing distances, image motion etc., both for foveal interrogation tasks and for visual search tasks. The paper discusses in some depth the major facets of pre-perceptual visual processing and their interaction with instrumental image quality & noise. It then highlights the statistical nature of visual performance before going on to consider a number of specific mathematical models of partial visual function. Amongst such specific models are versions covering foveal detection, detection during visual search, foveal recognition & identification, bar pattern thresholds, modelling of complex forms plus some mention of thresholds of motion awareness. Where appropriate these are compared with widely popular empirical models of visual function.