You can't run anything on the

You can't run anything on the GPU when your application enters the background. Doing so will result in it being instantly terminated. This means that you can't use GPUImage for any processing to be performed when your application is moved to the background.

If you need to do this, you will have to switch to a CPU-bound solution, like using vImage or Core Image's CPU side routines. Unfortunately, they lack many of the capabilities I have here.

Sunset Lake Software - Comments for "Running GPUImage in background"

You can't run anything on the