We establish the geometric origin of the nonlinear heat equation with arctangential
nonlinearity:
by deriving it, together and in duality with the mean curvature flow equation, from
the minimal surface equation in Minkowski space-time, through a suitable quadratic
change of time. After examining various properties of the arctangential heat equation
(in particular through its optimal transport interpretation à la Otto and its
relationship with the Born–Infeld theory of electromagnetism), we briefly discuss its
possible use for image processing, once written in nonconservative form and properly
discretized.