How can I put the compositor viewer node result back into Cycles? I am doing this experiment with Compositor Nodes and Cycles Nodes. There are times where I want to blur an image from Cycles and to bring it into Compositor, simply blur it and back to Cycles.

I have a feeling that this is not possible. But maybe there is a trick to be able to do this in a way that even though it is not realtime, it can be triggered and bake as needed?

A simpler test is if I am using Compositor, load an image, blur it or make adjustment and then export it into Viewer Node, is there in anyway I could ready that "Viewer Node" image into Cycles? -->  I tried this does not quite work, I am getting pink color.
You could probably do this with multiple Render Layers:


first layer renders or loads an image and blurs the result as desired
second layer renders the rest and composite it with the result of 1, either directly or by loading an image texture from file saved in 1.


example: