Bloom Linear

OpenMW Authors

Bloom shader performing its calculations in (approximately) linear light.

This shader comes with OpenMW, there's no need to install anything extra for it.
Shaders are enabled and configured with the F2 key while in game. I've had good results with loading this after the ssao_hq, godrays, and hdr shaders (from OMWFX Shaders).
If you're following a mod list, your shader chain in the settings.cfg file might look like this (with this load order):

chain = ssao_hq,underwater_interior_effects,underwater_effects,clouds,godrays,bloomlinear,wetworld,SSR,hdr,fxaa