Video denoising

Video denoising is the process of removing noise from a video signal. Video denoising methods can be divided into:

• Spatial video denoising methods, where image noise reduction is applied to each frame individually.
• Temporal video denoising methods, where noise between frames is reduced. Motion compensation may be used to avoid ghosting artifacts when blending together pixels from several frames.
• Spatial-temporal video denoising methods use a combination of spatial and temporal denoising. This is often referred to as 3D denoising.^[1]

It is done in two areas:

They are chroma and luminance; chroma noise is where one sees color fluctuations, and luminance is where one sees light/dark fluctuations. Generally, the luminance noise looks more like film grain, while chroma noise looks more unnatural or digital-like.^[2]

Video denoising methods are designed and tuned for specific types of noise. Typical video noise types are the following:

• Analog noise
  • Radio channel artifacts
    • High-frequency interference (dots, short horizontal color lines, etc.)
    • Brightness and color channel interference (problems with antenna)
    • Video reduplication – false contouring appearance
  • VHS artifacts
    • Color-specific degradation
    • Brightness and color channel interference (specific type for VHS)
    • Chaotic line shift at the end of frame (lines resync signal misalignment)
    • Wide horizontal noise strips (old VHS or obstruction of magnetic heads)
  • Film artifacts (see also Film preservation)
    • Dust, dirt, spray
    • Scratches
    • Curling (emulsion exfoliation)
    • Fingerprints
• Digital noise
  • Blocking – low bitrate artifacts
  • Ringing – low and medium bitrates artifact, especially on animated cartoons
  • Blocks (slices) damage in case of losses in digital transmission channel or disk injury (scratches on DVD)

Different suppression methods are used to remove all these artifacts from video.

• Image denoising

• Reduce noise in video