Luminance Contrast Testing
The provision of TGSIs, stair nosing and braille signage with sufficient luminance contrast enhances accessibility for all people, especially for those with vision impairment, and is now a regulatory requirement.
Luminance contrast compares the difference in the amount of light reflected (luminous reflectance) from a TGSI, stair nosing or braille sign with that of its surrounding substrate. Contrast difference percentages are specified in regulatory standards and the correct contrast difference must be confirmed for every location. At Korb, our technical staff are equipped with a state of the art tristimulus colorimeter. We offer on-site testing and advice with a detailed luminance contrast report to help you achieve compliant luminance contrast requirements.
DETERMINATION OF LUMINANCE CONTRAST
The determination of luminous contrast are set out by the Bowan-Sapolinski equation as per AS/NZS 1428.4.1:2009 E3.4. The luminance contrast (C) of the two surfaces (such as a tactile indicator and its surround) shall be calculated using the following equation: C=125(Y 2 -Y 1 )/(Y 1 +Y 2 +25), where Y 1 and Y 2 are the luminous reflectance values of the two surfaces.
The necessary luminous reflectance (there may be two values corresponding to TGSIs that are lighter and darker than the base surface) shall be calculated based on the following;
For integrated units: C=125(Y2-Y1)/(Y1+Y2+25)=30 For discrete units: C=125(Y2-Y1)/(Y1+Y2+25)=45 For composite discrete units: C=125(Y2-Y1 )/(Y1 +Y2+25)=60 Where Y2 is the lighter surface and Y1 is the darker surface
