How to create a cut out mask

I have a sphere, I want it to have a glow effect on the outside, so I add a Blurr node to it, now I want to insert and image in the middle of that sphere, using a circle with a face, setting texture to map an image and set it to transparent, because I want it to look like its on glass, so I do not want the glow of the inner sphere to show through, so how do I create a cut out mask (not the best description I know, so what do you call this) to remove the inner glow region of the sphere?


I’d rather used separate render layers, apply blurr just to one of them and then combine.

You can use render layers or object indexes. I like to use object indexes. They allow you to pick any combination of objects and make a alpha mask of those objects. In your case you could use that mask (the inverse of it) to add the glow to the original image with a mix node in the compositor.

Thanks, I added a Color Inverter and checked Alpha, then used an Add node and it seems to work fine now, it did mask out the center, still a little washed out, not sure what is causing that, I have a long way to go still.