Bloom

Bloom is a post-process effect that diffuses very bright pixels. This mimics lens artifacts of real cameras. This allows a better sense of what the actual intensities of the pixels are.

Reference

Panel:Render ‣ Bloom
Threshold
Filters out pixels under this level of brightness.
Knee
Makes transition between under/over-threshold gradual.
Radius
Bloom spread distance.
Color
Color applied to the bloom effect.
Intensity
Blend factor.
Clamp
Maximum intensity a bloom pixel can have.