| Quantitative assessment of commercial filter 'aids' for red-green colour defectives. | |
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MedLine Citation:
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PMID: 20883355 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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The claims made for 43 commercial filter 'aids', that they improve the colour discrimination of red-green colour defectives, are assessed for protanomaly and deuteranomaly by changes in the colour spacing of traffic signals (European Standard EN 1836:2005) and of the Farnsworth D15 test. Spectral transmittances of the 'aids' are measured and tristimulus values with and without 'aids' are computed using cone fundamentals and the spectral power distributions of either the D15 chips illuminated by CIE Illuminant C or of traffic signals. Chromaticities (l,s) are presented in cone excitation diagrams for protanomaly and deuteranomaly in terms of the relative excitation of their long (L), medium (M) and short (S) wavelength-sensitive cones. After correcting for non-uniform colour spacing in these diagrams, standard deviations parallel to the l and s axes are computed and enhancement factors E(l) and E(s) are derived as the ratio of 'aided' to 'unaided' standard deviations. Values of E(l) for traffic signals with most 'aids' are <1 and many do not meet the European signal detection standard. A few 'aids' have expansive E(l) factors but with inadequate utility: the largest being 1.2 for traffic signals and 1.3 for the D15 colours. Analyses, replicated for 19 'aids' from one manufacturer using 658 Munsell colours inside the D15 locus, yield E(l) factors within 1% of those found for the 16 D15 colours. |
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Authors:
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Jack D Moreland; Steven Westland; Vien Cheung; Steven J Dain |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Ophthalmic & physiological optics : the journal of the British College of Ophthalmic Opticians (Optometrists) Volume: 30 ISSN: 1475-1313 ISO Abbreviation: Ophthalmic Physiol Opt Publication Date: 2010 Sep |
Date Detail:
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Created Date: 2010-10-04 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 8208839 Medline TA: Ophthalmic Physiol Opt Country: England |
Other Details:
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Languages: eng Pagination: 685-92 Citation Subset: IM |
Copyright Information:
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© 2010 The Authors, Ophthalmic and Physiological Optics © 2010 The College of Optometrists. |
Affiliation:
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School of Life Sciences, Huxley Building, Keele University, Keele, UK. j.d.moreland@cns.keele.ac.uk |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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