Bug 512943 - Blur effects issues with alpha channel
Summary: Blur effects issues with alpha channel
Status: REPORTED
Alias: None
Product: kdenlive
Classification: Applications
Component: Video Effects & Transitions (other bugs)
Version First Reported In: unspecified
Platform: Other Other
: NOR normal
Target Milestone: ---
Assignee: Jean-Baptiste Mardelle
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2025-12-04 15:50 UTC by Gabriel Gazzán
Modified: 2025-12-04 15:53 UTC (History)
0 users

See Also:
Latest Commit:
Version Fixed/Implemented In:
Sentry Crash Report:

Attachments
blur issues on clips with alpha channel (2.54 MB, video/mp4)
2025-12-04 15:50 UTC, Gabriel Gazzán 		Details
test project with images used (56.20 KB, application/x-gzip)
2025-12-04 15:53 UTC, Gabriel Gazzán 		Details
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Description Gabriel Gazzán 2025-12-04 15:50:31 UTC 
Created attachment 187336 [details]
blur issues on clips with alpha channel

I just saw that the effects in the blur category aren't capable of correctly handling the alpha channel, in one way or another.

To exemplify it, please look at the attached video.

I've detected mainly two kinds of problems:
1. Edge handling (straight/premultiplied).
2. Not being able to extend the limits of the clip to accommodate the new pixels generated by the effect.

As I could see, all of those effects suffer from the first problem, while most of them also suffer from the second one.
Comment 1 Gabriel Gazzán 2025-12-04 15:53:21 UTC 
Created attachment 187337 [details]
test project with images used