Hurter and Driffield characteristic curve

Hurter and Driffield characteristic curve

[′hərd·ər ən ′dri‚fēld ‚kar·ik·tə¦ris·tik ′kərv]
(graphic arts)
A graph showing the dependence of the optical density of a photographic emulsion on the logarithm of its exposure to light. Abbreviated H-D curve.