footroom

foot +‎ room

footroom (uncountable)

1. Space for a person's feet, especially while seated.

   Coordinate terms: headroom, legroom

   • 2012, Phil Edmonston, Lemon-Aid New Cars and Trucks 2013:

     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; […]

2. (signal processing) Extra bandwidth for lower-than-expected values.

   Coordinate term: headroom

   • 2000, Wolfgang Ahnert, Frank Steffen, Sound Reinforcement Engineering: Fundamentals and Practice, page 177:

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

   • 2012, Charles Poynton, Digital Video and HD: Algorithms and Interfaces, page 45:

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

   • 2017, Steve Wright, Digital Compositing for Film and Video:

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