Oniric Glow Generator for Photoshop
https://www.compositenation.com/plugins/oniric

Generate bloom effect is one of the two core features of Oniric. It uses the inverse square law same as real light falloff does to create very smooth light transitions. Combined with our algorithms it works amazing with the "colorize" feature. Whe you hit the "apply" button, Oniric renders the bloom in 16bit so you don't have to worry about banding.