Two basic methods for spreadless nonlinear processing are reviewed--theta coding and the halftone method--and a broad class of threshold-decomposition-based nonlinear image processing operations is then described that relies on combining hard point nonlinearities with linear shift-invariant operations.
William T. Rhodes,
James M. Hereford,
"Nonlinear Optical Image Processing", Proc. SPIE 0960, Real-Time Signal Processing for Industrial Applications, (8 February 1989); doi: 10.1117/12.947798; https://doi.org/10.1117/12.947798