VISUAL CONTRAST FOR VISUALLY IMPAIRED PEOPLE -PROPOSITION OF PARAMETER, THRESHOLD AND MEASUREMENT SETUP, BASED ON EXPERIMENTS

摘要

Accessibility has become a prominent issue for urban planners and architects who are required to design fully accessible spaces. National and international regulations and norms exist for equipment designed to assist with a variety of handicaps. However, for visually impaired people little knowledge is available on which to base recommendations for accessibility. Visual contrast appears to be a key parameter in the detection and identification of surroundings, but what does visual contrast mean in practice, and how can it be simply defined for this field of application? CERTU, head of the scientific and technical network of the French Government, has been asked by the French Ministry of Sustainable Development to work on visual contrast to establish a reference that can be used for national regulations and proposed for adoption at European and International levels. This paper presents work performed for this task during the past two years. It leads to the current proposal of a contrast parameter, with thresholds defined by experiments with the visually impaired, and a measurement system to test the contrast of real systems in situ.