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Maniphest T70403

Ineffective bloom in render output when the background is transparent.
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Description

System Information
Operating system: win10 x64
Graphics card: Navidia GTX970M

Blender Version
Broken: Blender 2.80 and Blender 2.81-ff10ff782bde
Worked: (optional)

Short description of error
If I activate bloom in eevee and activate transparent background, the viewport will still show beautiful bloom, but If I render it, either render image or render animation, will output images in which bloom does not show at all.

Exact steps for others to reproduce the error
Based on the default startup or an attached .blend file (as simple as possible).
Add emission shader, Activate bloom, Activate transparent background, hit render.


Figure 1 is viewport, Figure 2 however is the final output. The blender file has also been attached.
BUG report.blend536 KBDownload

Related Objects

Event Timeline

Hoffman Heard (Hoffman) created this task.Sep 30 2019, 10:22 PM
Hoffman Heard (Hoffman) updated the task description. (Show Details)
Philipp Oeser (lichtwerk) added a subscriber: Philipp Oeser (lichtwerk).Oct 2 2019, 1:21 PM

Color is still there, it is just the Image Editor displaying it with the alpha applied
If you look at it in the Image Editor > Display Channels (top right corner dropdown) > Color (not Color And Alpha) you can still see the bloom in the image.
Also opening rendered images in an external Image Editor like Gimp and disabling the Alpha channel there displays the image correctly.
Dont think the postprocess bloom should be in the Alpha?

Philipp Oeser (lichtwerk) added a comment.Oct 2 2019, 1:34 PM

See also discussion in
https://devtalk.blender.org/t/rendering-with-transparent-png-doesn-t-render-the-bloom-effects-eevee/3472/21
https://blenderartists.org/t/rendering-with-transparent-png-doesnt-render-the-bloom-effects/1126303

There have also been multiple reports about this
T65269
T67110, T67566, T66465, T66263

So in the end, this really seems to be the same as T52680: Alpha difference Viewport/F12 , will merge these reports...

Philipp Oeser (lichtwerk) closed this task as a duplicate of T52680: Alpha difference Viewport/F12 .Oct 2 2019, 1:34 PM
Hoffman Heard (Hoffman) added a comment.Oct 2 2019, 1:46 PM
In T70403#787646, @Philipp Oeser (lichtwerk) wrote:

Color is still there, it is just the Image Editor displaying it with the alpha applied
If you look at it in the Image Editor > Display Channels (top right corner dropdown) > Color (not Color And Alpha) you can still see the bloom in the image.
Also opening rendered images in an external Image Editor like Gimp and disabling the Alpha channel there displays the image correctly.
Dont think the postprocess bloom should be in the Alpha?

Thanks for replying, your method works to show the bloom, although the problem is not only the image editor but the actual output as well.
Reading the discussion you posted, I see that bloom will disappear because of the way that blender handles alpha channel.
I wonder whether developers will try to change it in the future or just keep everything as it is now?
In the discussion I realize some people use composites node as a work around, In that case using other image/video editing tools seem more applicable than bloom in blender.