FFT3DFilter

The FFT3DFilter was designed to use the Fast Fourier Transform method for image processing in frequency domain. It is based on some advanced mathematical algorithmes of optimal filtration. It works not locally, but makes some delocalized (block) processing.
In 3D mode, it results in effect similar to partial motion compensation. This filter can reduce noise without visible quality loss and artefactes, even with quite strong settings. It can greatly improve compression and reduce encoded file size. Also it has option of limited sharpening without both noise amplifying and oversharpening (haloing).
So, it is a spatial-temporal (3D) filter, and works as follows:
- get current and some previous frames;
- divide every frame to small overlapped blocks;
- get frequency spectrum by windowed forward 2D FFT transform of every block of these frames;
- apply some filter to frequency spectrum;
- optionally sharpen image (in 2D frequency domain) by amplifying of some frequencies;
- make inverse 2D FFT transform of cleaned spectrum for every block;
- do windowed summation of cleaned overlapped blocks to output frame.
Overlapped blocks and weighting windows are used to prevent blockiness (and ringing). The blocks are overlapped by some value along their vertical and horizontal sizes. The lesser overlap, the faster processing, but with more visible grid artifactes.
Syntax:
FFT3DFilter (clip, float "sigma", float "beta", int "plane", int "bw", int "bh", int "bt", int "ow", int "oh", float "kratio", float "sharpen", float "scutoff", float "svr", float "smin", float "smax", bool "measure", bool "interlaced", int "wintype", int "pframe", int "px", int "py", bool "pshow", float "pcutoff", float "pfactor", float "sigma2", float "sigma3", float "sigma4", float "degrid", float "dehalo", float "hr", float "ht", int "ncpu")System requirementsAvisynth 2.5