Of the three, the FFT artifacts are far less (to my eye) distracting. It also makes the video look like it was shot through a screen door.įFT noise reduction will yield 'mosquito noise' around objects which move against a sharply contrasting background. Temporal noise reduction will often yield the 'pancake' face (sometimes called 'clay face') effect you described. Spatial noise reduction makes things look soft. This is the same basic math and technology that is at the heart of JPEG compression, and JPEG compression is what is at the heart of MPEG (MPEG-2 MPEG-4, etc) compression. The high frequencies are then modified, and the results recombined into normal video. With FFT denoising each portion of the video is first changed into 'frequencies,' with the quick transitions from light to dark (if the FFT is done in the luma space) representing high frequencies.

The frame is then returned to its original X-Y location after repair. This is done just for the purpose of getting a better comparison of what has actually changed, and also for picking what portion of the adjacent frame (or frames) to use for repairing the pixel. With the really exotic versions of this, the frame to be repaired is first 'motion compensated' so that it aligns as closely as possible with either the preceding or suceeeding frame. With temporal denoisers, each frame is compared to the adjacent frames, and if something is small and exists in only one frame, but not either the frame before or after, it is combined either with its surroundings, or is replaced with content from the adjacent frames. With spatial denoisers, small objects in each frame are blurred, or at least combined in some way with their surroundings, without much care for what happened in the previous or next frame. This technology is used all the time for sound (including Sound Forge and Izotope), but is not normally used for video. I am referring to an AVISynth plugin based on FFT (Fast Fourier Transform). There is a third beast, however, and I have had FAR better experience with it than with anything else. I have used virtually every noise reduction product and technology.

Denoiser ii vs neat video