Human Visual Sensitivity versus Wavelength:
Daylight and Dark Adapted

The following chart shows the relative sensitivity of human vision to light of a range of wavelengths for both daylight adapted (photopic) vision and dark adapted (scotopic) vision. The chart was constructed in Quattro Pro using equations given at the web page Radiometry and photometry in astronomy by Paul Schlyter, Stockholm, Sweden. The web page can be found at http://www.stjarnhimlen.se/comp/radfaq.html or at http://hem.passagen.se/pausch/comp/radfaq.html  Mr. Schlyter claims the equations are a good approximation to empirical data.

The equations are:

Equations for relative photopic and scotopic human visual sensitivity versus wavelength.

The photopic values apply when illumination is above 3cd/m2. The scotopic values apply when illumination is below 3 cd/m2. Wavelength (lambda) is in nanometers.

Graph of relative photopic and scotopic human visual sensitivity versus wavelength

Here is a link to a whole web book about visual perception, by Peter K. Kaiser at York University, Toronto, Canada. http://www.yorku.ca/eye/index1.htm

This web page maintained by
Mark D. Holm
mdholm@telerama.com

Updated January 6, 2005

Valid HTML 4.01! Valid CSS!