Eigengrau is a dark shade of gray, similar to black.
This box shows the color Eigengrau.
Color codes
In hex: #16161d
Eigengrau Media
Threshold increment versus background luminance for various target diameters (in arcmin). Data from tables 4 and 8 of Blackwell (1946), plotted in Crumey (2014). The flat curves at low light indicate Eigengrau.