according to this request here:
WebGL createPostProcessingShader returns null
I have made a postprocessing plugin example that blurs the pano image (with an approximated gaussian blur).
Here a demo:
Postprocessing Plugin Example - Multi-Pass-Blur
The plugin source:
The example xml: (changes the blur in a loop)
Here the full example for downloading:
The image will be blurred in 6 rendering passes with 9-taps/samples per pixel. That's quite a lot and a requires a good GPU for good performance.
When only lower blurring ranges are requires the number of passes could be reduced to 2 or 4 in the plugin source for better performance.