Chromatic aberration simulator (longitudinal and lateral) (simulates the effects of chromatic aberration)
Measuring resolution (eg., of a microscope or camera), using Airy pattern, FFT, MTF50.
Demosaicing: Constructing RGB pixels from a Bayer mosaic (how RGB pixels are created from raw file data)
Edge spread: LoCA Focus Analyser compared with QuickMTF (explores the relationship between edge spread and MFT)