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glow / bloom effect

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shaq1106    122
Hi. I'm just wondering what is different between glow effect and bloom effect. Look like same thing to me. Are these effects all related to HDR? I'm a little bit confusing. Can anybody explain about this? Some screen-shot may helpfulful for me. thanks.

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MJP    19755
Glow and bloom generally refer to the same effect. Of course there are several ways to implement this effect, with different tradeoffs involved for each.

HDR and Bloom are usually grouped together because using HDR generally requires you to change how you implement your bloom process. It's very hard to explain if you don't understand how HDR works and how it's implemented. In most cases, combining HDR with bloom can result in "better" bloom effects, or at least give you some more flexibility in how you handle things.

You asked for some pictures, so I took 3 screenshots from a (rather old) demo app. The first has no bloom and uses standard LDR rendering, the second has bloom with LDR, and the third is bloom combined with HDR. This is of course just a simple example an in no way represents the best that those 3 situations can look (I optimized my assets and lighting for HDR, so naturally the HDR pic looks best) I just wanted to demonstrate one of the neater effects you can acheive when you combine HDR and bloom. The effect I'm talking about is how pixels that are so bright that appear white can have a "glow area" that slowly fades to another color. You can see it quite clearly in those glowing spheres: with regular bloom they are drawn as white and therefore when bloom'ed they appear white, but with HDR the color is actually "really really bright blue". This means it comes out as white when you tone-map, but when you bloom it fades from white to blue.

No Bloom, No HDR

Bloom, No HDR

Bloom, HDR

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