I like to animate an object in blender and put some composite nodes together to make it look cool. Like blur, glare and stuff like that.
Then I want to export those images with transparency so I can put them over something else.
The problem is, saving as RGBA, only the alpha from the object is exported and the blur/glare effects OUTSIDE of the object bounderies get lost, because they have 0 alpha there.
Now my question is, is there a way to retain or generate the alpha for the effects, so that I have say a white glow around the object in the PNG like it looks in the output window?
This is not about how to achieve a glow on the object, when I use it afterwards. Yes, I probably could render it without effects and then put them on manually.
But its about the principle if Blender can do this.
Here my simple setup with the resulting image in photoshop in the lower left: