Footroom

Drivers say there's insufficient footroom; the brake and accelerator pedals are mounted too close to each other; narrow, poorly cushioned seats lack sufficient thigh support; […]

[…] the difference between signal-to-noise ratio and overload reserve (headroom) as well as noise (safety) margin (footroom).

To accommodate footroom, the number representation must allow negative numbers.

Footroom – the range of code values in the blacks of an image that encompass the variations in grain or noise.