Noise Reduction Suite (NRS) Filter for VirtualDub

NRS is designed to reduce differencies across frames (for better compression) and to cut out noise near frame borders. The filter provides two main areas of functionality: dynamic noise reduction and cropping/shifting.

The luminance functionality operates as follows:

  1. The old and new pixels are averaged (blended).
  2. The luminance of the new pixel is calculated and determines a threshold.
  3. If the absolute value of the difference between the blended pixel and the old pixel exceeds the threshold, then the unchanged new pixel is used; otherwise the blended pixel is used.
The important thing is how the thresholds are determined from the luminance of the new pixel. Human eyes are more sensitive in dark areas, so different thresholds are used according to the luminance of the pixels. And since the eyes are sensible to luminance changes in a logarithmic way the luminance range is split into 8 pieces and thresholds distributed along these pieces. To see how the thresholds are distributed, look at the "Luminance=Threshold" labels.

The cropping/shift functionality allows for cropping from any frame border(s), automatically centering the resulting area in the original frame size, and shifting the area as desired.

Version 1.4 [Source code]

Version 1.4 adds the ability to be imported into Avisynth.

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