Issues in specifying contrast in building elements for people with a visual disability

Stephen John Dain, Catherine Bridge, Mark Relf, Aldyfra Luhulima Lukman, Sarita Manandhar, Mei Ying Boon

Research output: Contribution to journalArticlepeer-review

Abstract

Standards writers, national and international, have used different contrast calculations to set requirements in building elements for people with visual impairments. On the other hand, they have typically set a single requirement (30%) for specifying the minimum contrast. The systems are not linearly related and 30% means something rather different in each system. OBJECTIVE: To provide a comparison of the various scales in order to illustrate the differences caused by multiple scales with a single compliance value, recommend a single scale for universal adoption and, if a new measure is problematic for implementation, to recommend the most perceptually uniform of the present methods. METHODS: We use the contrast between combinations of 205 paint colours to illustrate the relationships between the measures. We use an internationally accepted scale, with equal perceptual steps, as a 'gold standard' to identify the most perceptually uniform measurement scale in the existing methods. RESULTS: We show that Michelson contrast is the most perceptually uniform of the existing measurement scales. We show the contrasts in the proposed method that equate to the various current requirements. CONCLUSIONS: We propose that CIE Metric Lightness could be used as the contrast measure. Alternatively, Michelson contrast is the most perceptually linear of the current measurement scales.

Original languageEnglish
Pages (from-to)1219-1227
Number of pages9
JournalWork
Volume70
Issue number4
DOIs
Publication statusPublished - 2021

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