Image blur in compositor creates halo from alpha #80746

New Issue

Daniel Bystedt · 2020-09-13T15:49:47+02:00

Daniel Bystedt commented

2020-09-13 15:49:47 +02:00

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.59

Blender Version
Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-11 09:14, hash: 1b6dd42803
Worked: Worked: 2.91.0 Alpha, Hash 4ccd5bf5c6, date 2020-09-09 10:38
This is likely related to D8234: Use DrawManager for Image/UV Editor

Short description of error
When i render objects with [render settings > film > Transparent = True] (bpy.context.scene.render.film_transparent = True), and blur the rendered image in the compositor, I get a strange halo around the objects. This seems related to the blurred alpha. If I sample the pixel values of the halo in the image editor, the pixel values that I observe (bright) is not the same as the sampled pixel values (black)

Exact steps for others to reproduce the error

create some objects in the 3d view and frame them in the camera
set [render settings > film > Transparent = True]
Render the image
open the compositor and set [use nodes = True]
Connect render layers.image > blur > viewer
look at the viewer node in the image editor
Increase the blur of the blur node in the compositor and observe the halo around the objects

Jeroen Bakker messaged me on blender.chat and asked me to test the new submit D8234: Use DrawManager for Image/UV Editor, so I'm pinging @jeroen-10 Bakker (jbakker) and @Clément Foucault (fclem) to this bug report

Compositor blur.mp4

debug_D8234_blur_compositor_halo_v001.blend

**System Information** Operating system: Windows-10-10.0.18362-SP0 64 Bits Graphics card: GeForce GTX 1080/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.59 **Blender Version** Broken: version: 2.91.0 Alpha, branch: master, commit date: 2020-09-11 09:14, hash: `1b6dd42803` Worked: Worked: 2.91.0 Alpha, Hash 4ccd5bf5c658, date 2020-09-09 10:38 This is likely related to [D8234: Use DrawManager for Image/UV Editor](https://archive.blender.org/developer/D8234) **Short description of error** When i render objects with [render settings > film > Transparent = True] (bpy.context.scene.render.film_transparent = True), and blur the rendered image in the compositor, I get a strange halo around the objects. This seems related to the blurred alpha. If I sample the pixel values of the halo in the image editor, the pixel values that I observe (bright) is not the same as the sampled pixel values (black) **Exact steps for others to reproduce the error** 1. create some objects in the 3d view and frame them in the camera 2. set [render settings > film > Transparent = True] 3. Render the image 4. open the compositor and set [use nodes = True] 5. Connect render layers.image > blur > viewer 6. look at the viewer node in the image editor 7. Increase the blur of the blur node in the compositor and observe the halo around the objects Jeroen Bakker messaged me on blender.chat and asked me to test the new submit [D8234](https://archive.blender.org/developer/D8234): Use DrawManager for Image/UV Editor, so I'm pinging @jeroen-10 Bakker (jbakker) and @Clément Foucault (fclem) to this bug report [Compositor blur.mp4](https://archive.blender.org/developer/F8872634/Compositor_blur.mp4) [debug_D8234_blur_compositor_halo_v001.blend](https://archive.blender.org/developer/F8872629/debug_D8234_blur_compositor_halo_v001.blend)

Daniel Bystedt commented

2020-09-13 15:49:47 +02:00

Added subscribers: @jeroen-10, @DanielBystedt

Daniel Bystedt commented

2020-09-13 15:58:21 +02:00

Added subscriber: @fclem

Jeroen Bakker commented

2020-09-14 08:36:22 +02:00

Added subscriber: @Jeroen-Bakker

Jeroen Bakker commented

2020-09-14 08:36:22 +02:00

The cause of the halo is that the pixels samples contain some anti aliasing colors, but the alpha channel is 0.0. As it is 0.0 the pixel will be shown as pure emissive color. Depending on the solution of #80745 we might want to add an option to the compositor output nodes how the image should be treated.

Jeroen Bakker commented

2020-09-14 08:37:08 +02:00

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

Jeroen Bakker self-assigned this 2020-09-14 08:37:08 +02:00

blender-admin commented

2020-09-15 12:28:58 +02:00

This issue was referenced by f492c8d488

This issue was referenced by f492c8d488b7eb2166ca894e10a8128a1678a885

blender-admin commented

2020-09-15 14:18:35 +02:00

This issue was referenced by 78ea6302f1

This issue was referenced by 78ea6302f1c45992dd1166cc3978a2ba4201d638

Jeroen Bakker commented

2020-09-15 14:19:46 +02:00

Changed status from 'Confirmed' to: 'Resolved'

Jeroen Bakker closed this issue

2020-09-15 14:19:46 +02:00

Thomas Dinges added this to the 2.91 milestone 2023-02-08 16:20:31 +01:00

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Image blur in compositor creates halo from alpha #80746