Image Editor: Alpha (like Bloom) not showing properly again #81026

New Issue

Pablo Vazquez · 2020-09-21T12:01:54+02:00

Pablo Vazquez commented

2020-09-21 12:01:54 +02:00

System Information
Operating system: Linux-5.4.0-7642-generic-x86_64-with-debian-bullseye-sid 64 Bits
Graphics card: Quadro RTX 4000 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 440.100

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-21 08:49, hash: d72b5785eb
Worked: 2.91.0 Alpha around September 15th

Short description of error
The improvement done recently as part of the Image Editor refactor, that shows correct alpha values is no longer working.

{F8905803, size=full}

I made a video about it on September 15th, compiled that same day and it worked fine. But as of recently it no longer works.

Exact steps for others to reproduce the error
The easiest way to test is with EEVEE bloom, attached this simple file I used in the demo video:

bug_image_editor_bloom.blend

**System Information** Operating system: Linux-5.4.0-7642-generic-x86_64-with-debian-bullseye-sid 64 Bits Graphics card: Quadro RTX 4000 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 440.100 **Blender Version** Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-21 08:49, hash: `d72b5785eb` Worked: 2.91.0 Alpha around September 15th **Short description of error** The improvement done recently as part of the Image Editor refactor, that shows correct alpha values is no longer working. {[F8905803](https://archive.blender.org/developer/F8905803/image.png), size=full} I made [a video about it on September 15th](https://youtu.be/mQqV77PaOVs?t=88), compiled that same day and it worked fine. But as of recently it no longer works. **Exact steps for others to reproduce the error** The easiest way to test is with EEVEE bloom, attached this simple file I used in the demo video: [bug_image_editor_bloom.blend](https://archive.blender.org/developer/F8905784/bug_image_editor_bloom.blend)

Pablo Vazquez commented

2020-09-21 12:01:54 +02:00

Added subscriber: @pablovazquez

Jeroen Bakker was assigned by Pablo Vazquez

2020-09-21 12:02:21 +02:00

Jeroen Bakker commented

2020-09-21 14:00:33 +02:00

Issue introduced by 78ea6302f1

The render result is tagged in the shader as being not premultiplied. That seems to be incorrect. As the data is premultiplied. Need to check the actual state in on the render result, and how this is transferred to the shader.

Issue introduced by 78ea6302f1 The render result is tagged in the shader as being not premultiplied. That seems to be incorrect. As the data is premultiplied. Need to check the actual state in on the render result, and how this is transferred to the shader. ![Screenshot from 2020-09-21 14-10-23.png](https://archive.blender.org/developer/F8906092/Screenshot_from_2020-09-21_14-10-23.png)

Philipp Oeser commented

2020-09-21 14:58:55 +02:00

Changed status from 'Needs Triage' to: 'Confirmed'

Jeroen Bakker commented

2020-09-21 15:31:15 +02:00

Ok what I have found out so far.

alpha_bug.blend

The float buffer of this file when rendering is straight alpha. For the bloom effect to be visible it should be rendered to premultiplied. Changing the alpha association will render the alpha_bug.blend incorrectly. This points to a more indepth issue that we need to tackle.

The reason why this wasn't visible before was that the pure emissive colors were also rendered for straight alphas what isn't correct. I need to get the whole picture clear to find out which transformation is done when.

If you render, save to openEXR and load the openEXR back, the bloom is drawn correctly.

Ok what I have found out so far. [alpha_bug.blend](https://archive.blender.org/developer/F8906255/alpha_bug.blend) The float buffer of this file when rendering is straight alpha. For the bloom effect to be visible it should be rendered to premultiplied. Changing the alpha association will render the alpha_bug.blend incorrectly. This points to a more indepth issue that we need to tackle. The reason why this wasn't visible before was that the pure emissive colors were also rendered for straight alphas what isn't correct. I need to get the whole picture clear to find out which transformation is done when. * If you render, save to openEXR and load the openEXR back, the bloom is drawn correctly.

Daniel Salazar commented

2020-09-21 23:48:24 +02:00

Added subscriber: @zanqdo

blender-admin commented

2020-09-22 13:52:38 +02:00

This issue was referenced by b17cca6966

This issue was referenced by b17cca6966dd06be5fc66a5c1ece79bbfe6b39b7

Jeroen Bakker commented

2020-09-22 13:57:38 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Jeroen Bakker closed this issue

2020-09-22 13:57:38 +02:00

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Image Editor: Alpha (like Bloom) not showing properly again #81026