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What is Intrinsic Gray?

Eigengrau (German: “intrinsic gray” or “intrinsic grey”, lit. “own gray”; also called Eigenlicht (Dutch and German: “own light”), dark light, or brain gray, is the uniform dark gray background that many people report seeing in the absence of light.

The term Eigenlicht dates back to the nineteenth century,[1] but has rarely been used in recent scientific publications.

Common scientific terms for the phenomenon include “visual noise” or “background adaptation”. These terms arise due to the perception of an ever-changing field of tiny black and white dots seen in the phenomenon.[2]

Eigengrau is perceived as lighter than a black object in normal lighting conditions, because contrast is more important to the visual system than absolute brightness.[3] For example, the night sky looks darker than eigengrau because of the contrast provided by the stars.