RGB Separation node - Green Channel Problem #58083

New Issue

Alma Talp · 2018-11-27T11:45:26+01:00

Alma Talp commented

2018-11-27 11:45:26 +01:00

Win 7 64 Pro
Blender 2.79B
GTX 1080Ti

When using a packed texture*, the Ambient Occlusion map - packed to the Green channel - renders incorrectly.

See animated GIF,
I also attached a Blender file, jut set viewport to Cycles.

*'Packed texture ' means the typical method to use an RGBA texture to store PBR channels like Metalness, AO, Roughness, etc.

In this case: R=Metalness, G=AO, B=BUMP, A=Roughness

Thanks.Green Channel Problem.blend

Win 7 64 Pro Blender 2.79B GTX 1080Ti When using a packed texture*, the Ambient Occlusion map - packed to the Green channel - renders incorrectly. See animated GIF, I also attached a Blender file, jut set viewport to Cycles. *'Packed texture ' means the typical method to use an RGBA texture to store PBR channels like Metalness, AO, Roughness, etc. In this case: R=Metalness, G=AO, B=BUMP, A=Roughness Thanks.[Green Channel Problem.blend](https://archive.blender.org/developer/F5733835/Green_Channel_Problem.blend) ![Green Channel Problem.gif](https://archive.blender.org/developer/F5733842/Green_Channel_Problem.gif)

Alma Talp commented

2018-11-27 11:45:26 +01:00

Added subscriber: @AlmaTalp

msalv commented

2018-11-27 14:14:43 +01:00

Added subscriber: @moisessalvador

msalv commented

2018-11-27 14:14:43 +01:00

I tested it, it seems that the alpha affects the green channel. I saved it as EXR and it doesn't give that problem.

At first I was about to say that it must be a problem with the TGA format, not with Blender, but the truth is that the data of the green channel is untouched, so the alpha affecting the rgb must happen on the Blender side. For my buck, it's a bug. Let's see if a developer confirms it.

In the meantime, as a work around, you can save it as EXR, or go to the properties of that image and disable "use alpha" (see gif)

I tested it, it seems that the alpha affects the green channel. I saved it as EXR and it doesn't give that problem. At first I was about to say that it must be a problem with the TGA format, not with Blender, but the truth is that the data of the green channel is untouched, so the alpha affecting the rgb must happen on the Blender side. For my buck, it's a bug. Let's see if a developer confirms it. In the meantime, as a work around, you can save it as EXR, or go to the properties of that image and disable "use alpha" (see gif) ![gif.gif](https://archive.blender.org/developer/F5734789/gif.gif)

Alma Talp commented

2018-11-27 14:17:20 +01:00

Thanks you, it clearly seems to be a bug to me. As for real-time engines TGA is a very popular format, hopefully it will be fixed soon.
So it will keep the Cycles Principled-Unity-Unreal, etc. texture usage easy.

Thanks you, it clearly seems to be a bug to me. As for real-time engines TGA is a very popular format, hopefully it will be fixed soon. So it will keep the Cycles Principled-Unity-Unreal, etc. texture usage easy.

Stephen Swaney commented

2018-11-27 14:19:40 +01:00

Added subscriber: @StephenSwaney