VirtualDub: Afterimage filter


[ Japanese ] I created a video filter for VirtualDub (free video processing software) called "Afterimage". This generates afterimage effect, a kind of motion blur effect also known as "light trail" effect. Useful for time lapse movies of night skies, especially meteor showers: with this filter, meteors will fade to disappear, instead of being shown only in single frame. It is also possible to generate star trails.


This is a HD movie, so please enable HD mode and view it fullscreen.


[ Download Afterimage Filter V0.1 ]

Sorry but source code is not yet available.

UNZIP, then copy vdf file to "plugins" subfolder in your VirtualDub folder. If you do not yet have VirtualDub, you can get it from

How to use


  • Multiplier: greater value result in greater effect.
  • Subtractor: smaller value result in greater effect.

"Multipier = 1.0 & subtractor = 0" result in light is eternally persistent, to generate star trails.


It simply applies this calc for each R, G and B channels:

  1. P1 = last frame
  2. P2 = source frame
  3. P1 = Multiplier * P1 + (1.0 - Multiplier) * P2 - Subtractor
  4. Result = Brighter (P1, P2)


I apologise that I am writing in english and not Japanese but I am from Canada. Your "Afterimage" filter is amazing but I would like to know if there is a way to get longer trails. The subtractor 1 is too fast in some circumstances.

Would altering the frame rate change how quickly the trails decay?

Thanks again for your work!

No problem, I can read/write English.

How about subtractor of 0.0 and multiplier of 0.99? It might result in the longest trails but not permanent.

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This page contains a single entry by Tagoshu published on April 9, 2012 12:06 PM.

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