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HDR/Bloom over the years ... explain the differences in quality please

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Hello,

there is something I noticed about bloom in more modern engines compared to older ones. In the past, when I moved the camera slowly, sometimes I was able to see a "flickering" effect, which very much looked like the result of a low-res blur texture used for the bloom effect (meaning that the "flickering" was the result of aliasing). This makes sense - back then, GPUs did not have enough computing power for higher-res blur textures.

In modern games, this artifact seems to be gone. In addition, the bloom effect now extends much farther outwards. ~10 years ago, the bloom effect sometimes looked like a halo, because the "glow" only extended a bit beyond the bright surface.

I attached some screenshots to show what I mean.

The first picture highlights what can happen when using a very low res blur texture. The second and third picture from the top are how bloom used to look like in older games: intense, bright, and did not extend much beyond the glowing surface itself. Compare this with the bloom effect in Hitman caused by the sun: much more nuanced, but extends much further outwards, completely over the guy in the middle.

I do not think this is a billboard texture for the sun's glow, since I have seen similar blur in other scenes in Hitman. So my current thought is that IO simply used a much bigger blur texture, and much bigger 1D gaussian blur kernels (not just 3 or 5 taps, but perhaps 15, 17 etc.) Or, perhaps there is a better, more efficient, nicer looking method for simulating bloom nowadays compared to using a gaussian blur on the frame's bright areas? Does anybody know more?

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The flickering is still a common issue nowadays because of the specular aliasing.
Nowadays the bloom can also be done using multiple pass at multiple resolution.
The luminance is still a choice on the bright pass but some people prefer to use a factor on the full image like : Image * 0.1.
This brightpass using a factor result to a full image bloom effect instead of only the luminance part.
But doing the luminance threshold to -1 gives also the bloom on the full image.

Edited by Alundra

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Without even talking about performance considerations, PBR also made HDR and bloom more physical, before that it was the artists who tweaked it, now they set the exposure and the tonemapping technique, and bloom is a "natural consequence" of it. ;)

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