AviSynth plugin to convert a premultipled RGB32 clip to straight matted alpha. AviSynth's Overlay() function requires straight matted input and will product artifacts if given a premultiplied clip. This plugin performs the appropriate conversion on the alpha channel to prevent this.
Eyeon Fusion is known to only produce premultiplied RGBA videos as well as improperly configured versions of Adobe After Effects. Other video compositing solutions may also suffer the same issue.
- Unpremultiply (clip)
- clip =
- Input clip to be unpremultiplied. Input clip must be RGB32, also known as RGBA. All other input types should fail with an error message.
- clip =
Version Date(D/M/Y) Changes
20121231 31/12/2012 - The bottom row and right column of the lookup table were not being initialised.
20121227 27/12/2012 - Fix a rookie mistake in not clamping the intermediate results between 0 and 255. - Also changed to uses a fast 65K lookup table instead of the slow in place idiv's.
20081229 29/12/2008 - Initial release.
- Doom9 Forum - Layer and Overlay operation giving wrong results with RGBA image source
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