Bloom
Also said as Glow, Light bloom, Real-time glow
Bright parts of the picture bleed soft light into the pixels around them, the way light scatters in your eye or in a camera lens. It works by copying the brightest pixels, blurring them, and adding them back.
Screens cannot show how bright the sun is, and bloom makes a thing feel brighter than the pixel really is. Too much and everything looks as if the lens has been smeared with butter.
Say it
“Add bloom only above a brightness of 1.0, so only lights and magic glow, not white walls. Spread it over five blur levels at low intensity, and keep it under 15% on the HUD.”
Where you’ve seen it
The developers of Tron 2.0 published their Real-Time Glow method in 2004, and that article spread the technique across the industry. Heavy bloom soon became a mark of its era.
Not to be confused with lens flare
Bloom is a soft glow around a bright thing. A lens flare is streaks and circles caused by light bouncing inside a camera, and it can sit far from the light.