cryptomatte file output produces incorrect matte image #63270

Closed
opened 2019-04-04 09:29:06 +02:00 by afaenger · 14 comments

System Information
Operating system: Windows 10 Pro 64 Bit
Graphics card: GTX 750 TI

Blender Version
Broken: blender-2.80-a813e259d630-win64, master, 2019-04-03

Short description of error
The matte image written to disk is wrong after the file output node is changed

Exact steps for others to reproduce the error

  1. load the file "archiviz5_bugtest1.blend"
  2. render once
  3. change the "File Output" node. Click on "Add Input", connect Depth (or Alpha) from "Render Layers" to Image_002.
  4. render once more. The "Matte" image_001 written to disk now is wrong ("C:\blender-output\Image_0010004.png"). The matte image displayed in blender is still correct however.

If the edited file is saved now and blender is restarted, then the rendering will be correct again

Also, even if the "File Output" node is restored to its previous state (the additional file output is removed),
then the rendering will always be wrong until blender is restarted.

archiviz5_bugtest1.blend

Image_0010004_correct.png

Image_0010004_wrong.png

**System Information** Operating system: Windows 10 Pro 64 Bit Graphics card: GTX 750 TI **Blender Version** Broken: blender-2.80-a813e259d630-win64, master, 2019-04-03 **Short description of error** The matte image written to disk is wrong after the file output node is changed **Exact steps for others to reproduce the error** 1) load the file "archiviz5_bugtest1.blend" 2) render once 3) change the "File Output" node. Click on "Add Input", connect Depth (or Alpha) from "Render Layers" to Image_002. 4) render once more. The "Matte" image_001 written to disk now is wrong ("C:\blender-output\Image_0010004.png"). The matte image displayed in blender is still correct however. If the edited file is saved now and blender is restarted, then the rendering will be correct again Also, even if the "File Output" node is restored to its previous state (the additional file output is removed), then the rendering will always be wrong until blender is restarted. [archiviz5_bugtest1.blend](https://archive.blender.org/developer/F6910076/archiviz5_bugtest1.blend) ![Image_0010004_correct.png](https://archive.blender.org/developer/F6910138/Image_0010004_correct.png) ![Image_0010004_wrong.png](https://archive.blender.org/developer/F6910139/Image_0010004_wrong.png)
Author

Added subscriber: @afaenger

Added subscriber: @afaenger

Added subscribers: @Jeroen-Bakker, @ZedDB

Added subscribers: @Jeroen-Bakker, @ZedDB
Jeroen Bakker was assigned by Sebastian Parborg 2019-04-04 16:02:42 +02:00

@Jeroen-Bakker feel free to reassign if this is not for you.

@Jeroen-Bakker feel free to reassign if this is not for you.
Member

Added subscriber: @JacquesLucke

Added subscriber: @JacquesLucke
Member

@afaenger, are you able to reproduce the behavior in a new, smaller file?

@afaenger, are you able to reproduce the behavior in a new, smaller file?
Author

No, not tried as I've basically no experience with blender. I've just started to play around a bit and do some tutorials. The file is was downloaded from the 2.8 demo site https://www.blender.org/2-8/

No, not tried as I've basically no experience with blender. I've just started to play around a bit and do some tutorials. The file is was downloaded from the 2.8 demo site https://www.blender.org/2-8/
Member

Seems like a color pipeline issue. The matte contains the 'lines' but they are not visible as it is stored in a value buffer (RAW buffer). When connecting a value directly to a color socket the data used as a linear color when displayed the display transform will be put on top. When exporting to PNG the colors are converted to sRGB.

image.png
When storing the matte in the Alpha channel of the color it will not be converted and you will see the right information.

I am not able to reproduce the issue you describe. (I was some time ago). Can you check if this is still failing.

Seems like a color pipeline issue. The matte contains the 'lines' but they are not visible as it is stored in a value buffer (RAW buffer). When connecting a value directly to a color socket the data used as a linear color when displayed the display transform will be put on top. When exporting to PNG the colors are converted to sRGB. ![image.png](https://archive.blender.org/developer/F7064773/image.png) When storing the matte in the Alpha channel of the color it will not be converted and you will see the right information. I am not able to reproduce the issue you describe. (I was some time ago). Can you check if this is still failing.
Author

Tested again with blender-2.80-d525c76003b3-win64 (May 27th) and followed the steps as described above. The issue is still there and the png file written in 4) contains the unexpected lines; the viewer never shows the lines.

With the "set alpha" workaround, the lines don't appear.

Tested again with blender-2.80-d525c76003b3-win64 (May 27th) and followed the steps as described above. The issue is still there and the png file written in 4) contains the unexpected lines; the viewer never shows the lines. With the "set alpha" workaround, the lines don't appear.
Member

Lemme try again.
Result step 1:
Image_0010004.png

Result after step 4:
Image_0010004.png

Both results are identical. The exposure of the file you are using is set to 5.5 what destroys the visual presentation of the data. When set to normal values you will also see the stripes in the viewport.

image.png

Is this the same result you get?

Lemme try again. Result step 1: ![Image_0010004.png](https://archive.blender.org/developer/F7075296/Image_0010004.png) Result after step 4: ![Image_0010004.png](https://archive.blender.org/developer/F7075303/Image_0010004.png) Both results are identical. The exposure of the file you are using is set to 5.5 what destroys the visual presentation of the data. When set to normal values you will also see the stripes in the viewport. ![image.png](https://archive.blender.org/developer/F7075316/image.png) Is this the same result you get?
Author

Yes, I get the same result in the viewer now if I change the settings to
Scene->Color Management: View Transform=Standard (instead of Filmic), Exposure=0.0 (instead of 5.5)

The stripes are not visible in the viewport if exposure is above ca. 0.7-0.8.

I think I understand now why the stripes are visible/invisible. But why is the behavior not consistent with the steps I described above? Shouldn't be the rendering results always be the same, no matter if I restart the application or add or remove some file outputs?

Yes, I get the same result in the viewer now if I change the settings to Scene->Color Management: View Transform=Standard (instead of Filmic), Exposure=0.0 (instead of 5.5) The stripes are not visible in the viewport if exposure is above ca. 0.7-0.8. I think I understand now why the stripes are visible/invisible. But why is the behavior not consistent with the steps I described above? Shouldn't be the rendering results always be the same, no matter if I restart the application or add or remove some file outputs?
Member

I am not able to detect any inconsistencies between step 1 and 4. You still are?

I am not able to detect any inconsistencies between step 1 and 4. You still are?
Author

Yes, e.g. when exposure is set to 1. The viewport then contains no stripes, the png output contains them sometimes. I think the rendering results should always be the same in order to correctly work with the scene. Basically when using higher exposure values, then the issue appears.

Yes, e.g. when exposure is set to 1. The viewport then contains no stripes, the png output contains them sometimes. I think the rendering results should always be the same in order to correctly work with the scene. Basically when using higher exposure values, then the issue appears.
Member

Changed status from 'Open' to: 'Archived'

Changed status from 'Open' to: 'Archived'
Member

We are aware of the limitations of blender single channel image pipeline. We intend to solve this in the future were we give users more control on the color spaces.

For now we will close this task as it is not a bug.

We are aware of the limitations of blender single channel image pipeline. We intend to solve this in the future were we give users more control on the color spaces. For now we will close this task as it is not a bug.
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Reference: blender/blender#63270
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