eq filter does not maintain transparency

[Jozef Chutka]

Using eq filter, the transparency information is lost and black pixles are rendered instead.

How to reproduce:

ffmpeg -filter_complex "color=color=green:size=1280x720[v];movie=input/rainbow.png,format=argb,eq=saturation=1,[v]overlay" -frames:v 1 output/out-eq.png -y

Notice, there is a small cut in the middle of rainbow.png. When using eq filter this part gets rendered as black instead of the proper background color.

Removing the eq from the chain, it does the job properly

ffmpeg -filter_complex "color=color=green:size=1280x720[v];movie=input/rainbow.png,format=argb,[v]overlay" -frames:v 1 output/out.png -y

The issue exists with 4.4.1 and also latest builds.

[Jozef Chutka]

potential fix is to use alphaextract+alphamerge however this might leave dark blending artefacts on semitransparent pixels

[Michael Koch]

I can't reproduce this problem. In the output image the hole in the image is green.
Did work with a 2 weeks old Windows build, and also with the latest build from today.

Michael

[Jozef Chutka]

Hi Michael,

thanks for looking into it, seems my "latest" was a bit older. I can confirm its working with current latest (86a2123a6e), however not with 4.4.1.

Any chance this would also land into 4.4.x?
Or what are the plans for 4.5 release?

[Michael Koch]

Replying to Jozef Chutka:

Hi Michael,

thanks for looking into it, seems my "latest" was a bit older. I can confirm its working with current latest (86a2123a6e), however not with 4.4.1.

Any chance this would also land into 4.4.x?
Or what are the plans for 4.5 release?

I can't answer these questions because I'm not a developer. From my point of view, it makes sense to always use the latest version.

Michael