LUMINANCE AND CONTRAST FOR SIGN LEGIBILITY AND COLOR RECOGNITION

A laboratory study of sign legibility has shown that a contrast of between 30 and 50 percent is required to maintain 75th percentile legibility. Legibility distance increased gradually with greater contrast to about 80 percent; above a luminance ratio of 5 to 1, legibility did not increase greatly. As ambient levels increased, legibility distance increased linearly with the logarithm of either the letter or the sign luminance, whichever was greater. Five color combinations were measured. This report gives additional results on color recognition and applies the effects of luminance and contrast to legibility distance for 11 color combinations, after corrections were made for letter and stroke, width. A method for estimating legibility was developed for black and white letter and sign combinations. The effects of luminance and contrast on color recognition at five ambient levels showed the need to increase luminance and contrast as ambient levels increase. Laboratory luminance data, confirmed by two sets of outdoor measurements, furnished a basis for determining the luminance ratios used in the legibility estimates. A basis for estimating glance legibility distance in relation to ordinary legibility (long viewing time) is suggested. /Author/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/trr/1976/611/611-002.pdf
• Record URL:
  https://scholar.google.com/scholar_lookup?title=LUMINANCE+AND+CONTRAST+FOR+SIGN+LEGIBILITY+AND+COLOR+RECOGNITION&author=T.+Forbes&publication_year=1976
• Availability:
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• Supplemental Notes:
  • Publication of this paper sponsored by Committee on Visibility. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Authors:
  • Forbes, T W
• Publication Date: 1976

Media Info

• Media Type: Print
• Features: Figures; References; Tables;
• Pagination: pp 17-24
• Monograph Title: Railroad-highway crossings, visibility, and human factors
• Serial:
  • Transportation Research Record
  • Issue Number: 611
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Brightness; Color vision; Contrast; Distance; Highway safety; Laboratory studies; Legibility; Traffic signs
• Subject Areas: Highways; Safety and Human Factors;

Filing Info

• Accession Number: 00163039
• Record Type: Publication
• ISBN: 0309025877
• Report/Paper Numbers: HS-021 004
• Files: TRIS, TRB
• Created Date: Oct 13 1977 12:00AM