Nodes have colored in/output to avoid mixing data. It’s not a bug. The only issue with Blender compositor is that it gets really slow with big node scripts if compared to other compositing softwares like Natron.
Okay i start to understand…
I was tricked by the backdrop wich does not represent the compositor nodes result but the final result.
eg the input image mixed with the nodes result.
This means i cannot get rid of the input image in the backdrop. If my nodes setup needs for example to make the final result semi-transparent i’ll get this result with the input image overimpressed.
This simply makes the backdrop totally useless^^
Hopefully the file-output node and the viewer node output things properly
Aside this, and unfortunately, the result of an F12, shown in the blender render window seems to be fuc*ed-up. Alpha values changed in compositor give wrong results in blender view render.
Maybe it comes from an obfuscated value or parameter somewhere in the properties window ? but i found none so far
Finally and though the visual result in the blender render window is incorrect from an alpha point of view, the saved file appears to be OK
wich is a good new
It’s an auxiliar data to assist with your compositing. Some composites may affect your alpha values and get undesired outcomes. It’s always good to look at your alphas to avoid calculations errors. Render layers, alphas, AOV’s will probably be used in another softwares, but with Blender you have an option/freedom to use it’s compositor. Other compositors can easely switch between layers (AOV’s) to assist debugging your compositing script.
In this case, my object RGB is good with Denoise node, yet I’m getting very bad shadows because of my alpha. Requires more sampling or a different compositing setup.
If you do want to extract several AOV’s from your scene, it’s better to use the File Output node with multiple outputs. By learning softwares like Natron, Nuke, After Effects you will get more aware from all nodes. It’s a start to VFX compositing.
