I know nothing about OpenGLES, but I am still intrigued.
I have used fastBlur and the RenderScript blur, see here:
http://www.b4x.com/android/forum/threads/blur-effect-demo.40920/
There is always trickey involved in blurring, the main thing is to down sample the image before you blur it (I would suggest atleast 4 times).
From what I read, blurring is a two pass operation for the GPU, for some reason the GPU cannot do it so fast, this surprises me because:
- iOS uses a frosted glass effect which is effectively blur plus some alpha/color
- Android used to have BLUR_BEHIND_FLAG pre 2.3 I think (removed due to performance reasons)
- Some ROMs like MIUI are still using blur
Maybe they all are doing it on the CPU I guess.