Colour vision deficiency (CVD), often and erroneously called colour-blindness, is the collective term for a variety of abnormal physiological conditions, usually congenital, which result in fewer colour responses than normal. Despite the surprisingly high incidence of CVD (8% of men are colour vision deficient) very few commercial interfaces tackle the problem explicitly. This thesis reviews the different types of accessibility problems encountered by colour vision deficient computer users. It reports results from a questionnaire study designed to ascertain the extent to which CVD impacts computer use, the frequency at which people with CVD experience problems and the severity of these problems. This thesis demonstrates how computational models of CVD can be applied to a variety of existing software tools and interfaces to improve computer accessibility for people with CVD. Specifically, it shows how it is possible to integrate models of CVD and measures of colour difference to facilitate the selection of accessible colour schemes and to automatically map combinations of colours that colour vision deficient people find hard to discern using multi-dimensional scaling. The recolouring algorithm is evaluated using a computerised version of the standard Ishihara pseudoisochromatic plate colour vision test. The effect of applying the algorithm is to decrease (increase) error (performance) significantly for both simulated and real colour vision deficient observers so that it is comparable to the error obtained by a normal colour observer. In addition to introducing a fully automatic recolouring method, a new semi-automatic recolouring method is described along with an interface that allows the method to be delivered as an adaptive technology. The interface allows users with CVD to recolour images for their own colour vision impairment in real-time. The interface is evaluated using a perceptual image similarity task, highlighting the benefits and limits of the proposed method.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:502557 |
| Date | January 2008 |
| Creators | Jefferson, Luke Alexander |
| Publisher | University of East Anglia |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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