Importance of Light Reflectance Value Contrast for Signage
Vital to signage design, LRV codes appear on paint swatches and fan decks. Understanding LRV is crucial when choosing color contrast between signage text and background, therefore it is most commonly used and understood by signage consultants, architects, environmental graphic designers and interior designers.
LRV is the acronym for Light Reflectance Value. Not to be conflated with vividness, value speaks strictly to the lightness or darkness of a color.
LRV is a measurement for the total quantity of visible and useable light reflected by a surface when illuminated by a light source. Conversely, LRV also tells you how much light a color absorbs.
LRV runs on a scale from 0% to 100%.
0% = theoretical absolute black, however the blackest blacks have an LRV of about 5%
100% = theoretical absolute white, however the whitest whites have an LRV of about 85%
Think greyscale – if you were to place your preferred color choices for signage text and signage background on the greyscale, would they have a high level of contrast? Imagine red and green, colors which are opposites on the color wheel. While they would have a high color contrast, they would not have a high LRV contrast. Therefore, this combination would not lend itself well to signage.
Paying attention to LRV contrast is critical for signage visibility.
The Americans with Disabilities Act Accessibility Guidelines (ADAAG) recommend a contrast in Light Reflectance Values between sign text and background colors of 70% or above. However, this an ideal guideline and not a requirement – value contrasts below the 70% rule of thumb can still provide enough contrast for low vision users to read clearly.
ASI has an LRV Contrast Calculator to simplify the process of ensuring your signage color choices meet or come close to the 70% contrast mark. Alternatively, you can use the calculation Contrast % = [(B1 – B2) / B1] x 100, where B1 = LRV of lighter area and B2 = LRV of darker area.
1. Signage with a reverse contrast, a dark background with white letters, make the signs easiest for low-vision users to read.
2. Signage in dark areas should be illuminated internally or by additional task lighting.
3. LRV Contrast between sign text and background colors of 70% or above, calculate here.
Rubin, G. S., & Legge, G. E. (1989). Psychophysics of reading: VI. The role of contrast in low vision. Vision Research, 29(1), 79–91. https://doi.org/10.1016/0042-6989(89)90175-2
LRV Light Reflectance Value of Paint Colors. (2019, October 17). Retrieved from https://thelandofcolor.com/lrv-light-reflectance-value-of-paint-colors/.
Value Contrast. (n.d.). Retrieved from http://www.designforsight.com/valuecontrast.html.