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Visual Displays > Text - 5 of 9
 
 


Strokewidth-to-Height

Strokewidth and the ratio of strokewidth-to-character height are also important font characteristics that affect text legibility. A lower ratio is preferred down to a limit of 1:6 for black characters on a white background and a limit of 1:8 for white characters on a black background.

  • Positive and Negative Image Effects - Optimum ratios for light characters on a dark background and dark characters on a light background differ due to "irradiation" effects. That is, light characters or symbols tend to "spread" or "bleed" into the adjacent dark background. To accommodate these differences, recommendations for symbol strokewidth-to-character height ratios are:
    • Positive Image - Dark characters on a light background - 1:6 to 1:8.
    • Negative Image - Light characters on a dark background - 1:8 to 1:10.
  • Irradiation Effects - "Irradiation" effects are accentuated by highly illuminated displays and/or by user dark adaptation.
  
     
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