In principle, PCM digital systems have the lowest level of nonlinear distortion at full signal amplitude.
From the en.wikipedia.org
He came up with the idea for a new form of audio loudspeaker, one that would greatly reduce distortion by replacing the nonlinear mechanical spring with a linear air cushion.
From the en.wikipedia.org
Nonlinear intrinsic parameters such as lens distortion are also important although they cannot be included in the linear camera model described by the intrinsic parameter matrix.