How Big Budget AAA Games Render Bloom 

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I'm almost surprised there isn't just a hardware implementation for FFT in modern GPUs, it seems like it would be useful for many things

"Back in the day, we developers thought it looked awesome and so next-gen, and it kinda did, so how about shut up." Amazing. Thank you for all the info, btw!

Using FFT for blurring and bloom is really awesome, I'm definitely going to play with that

using the fft for image processing is really interesting, something I will definitely look into one pedantic note though is that the karis average is actually for suppressing bright pixels not preserving them. The karis average helps with fireflies and shimmering artifacts by preventing really high hdr values from overwhelming the ultimately very small sample set of pixels.

I love your explanations, they're so clear and concise, it really helps me understand these complex topics better even without a formal education. thanks so much for what you do :)

i have a feeling that some of the intense color grading and bloom seen in the 2000s was at least partly inspired by Need for Speed Most Wanted without taking into account why they did it and what look they were trying to emulate (a stylized bleach bypass)

FFT-based glare is the same method I implemented for Megamind. It turns out that Fraunhofer diffraction through an aperture is essentially equivalent to an FFT. With that and making sure you rescale appropriately for each wavelength of light, you get the point spread function, which you can inverse-FFT and use to convolve. But since Fraunhofer diffraction is equivalent to an FFT anyway, the inverse FFT just gets you back to the simulation of your aperture, and you can just use that as your convolution filter... This means you can simulate the bloom based on a lens or even a human eye as long as you can adequately simulate the aperture. Yes Fresnel diffraction is more appropriate for an eye because of the short distance between the pupil and retina, but it's still pretty convincing in producing a glare that looks like glare you'd personally experience through your own eyes. It would be cool to see FFT blur be practical in realtime... It is just plain simple and generic in the same way that ray tracing is.

FFTs are super powerful. They are commonly used in signal processing to do essentially the opposite of bloom: remove artifacts of the sensor. This reverse process, so-called deconvolution, can for example remove the 6-star artifacts on the JWST images.

This is an insane amount of info on bloom in just 13 minutes! Thanks to you I know there's faster and prettier ways of doing bloom and I might implement them in the future!

seriously perfect video, I cannot say enough how refreshing the format, tone, and pacing was. thank you

13:11 A few more iterations in hardware and a single PC will use more electricity than everything else in the house combined. 💀

Wow, the implementation of the convolution bloom is amazing

One of the few channels I actually get exited when new content is released!

your vids are a blessing, and the demonstration of convolution bloom was especially eye-opening

Fun fact: Unreal Engine 5 make Convolution Bloom much cheaper by simply downsampling the source frame to 1/4th of the resolution, essentially cutting down the load by 93.75%. You can toggle back to the half resolution to get higher accuracy bloom for cinematic quality.

If the FFT is cheap enough, I'd love to try animating or dynamically changing the bloom shape one the fly.

HE's BACK! You are a legend my friend. You helped me so much along the way, thank you.

Please keep going with these topics (more post-processing)! It's always a good day when you release on of your videos! 🙂

There is a correct way of doing bloom, it's just way too computationally expensive to do in real time. The idea is to get the result of the diffraction of light around the aperture of th light capturing device ( eye or camera). The "blur and down sample" approach from advanced warfare was found to give results very close to the 1/d³ falloff of a real airy spot, which is the bloom you obtain with a round aperture at the focal point. The fact that it gets faster due to downsampling is a nice side-effect.

What an excellent video! Super clear description of bloom.

Incredible video, thorough and cohesive, very easy to understand visualization material, while also presenting a pretty complete analysis on how and why the technique advanced throughout the years. It might've been interesting to explain why bilinear taps were used, despite it being "obvious" for people already in the know.

Well where was this video 2 years ago when I needed it? I think the shader I ended up using was Unity Style, so it’s nice to heave a clear explanation of how it works. Thanks!

Thanks for sharing. We usually take it for granted and cramp bloom to max hehe

The FFT is a heavy operation but it really frontloads your computational work as so many involved image manipulations can be done incredibly cheaply once you do get that transform.

I'm glad you're still teaching. Industry massively lacking in content for anything beyond the Unity scene-graph, unless you dive into shaders... which I see you have a course now.

As always great video! The FFT stuff is insane

Sick, I love the deep dives

You're the MadSeason of game programming, so relaxing to hear.

Dude you are a god, I love watching your videos and learning from you

Great video! Very informative and interesting.

Those videos are just amazing for a graphics programmer like me, keep it up!

I've seen videos on the fourier transform but only now do I realize how awesome it is.

Great video again Simon! Bloom is awesome and it's great to hear about how the different engines implement it.

Great video! I think some of the better implementations I saw of 2000s era bloom was to use the alpha channel in the frame buffer to mask areas that should glow like lights or neon signs. That way it prevented the thresholding problem of causing white objects to glow unintentionally.

AngeTheGreat has an amazing “What is bloom” video from a photo real perspective. He makes many great simulation videos and in this one it goes into how Fraunhofer Diffraction is simulated for rendering, which is representative to this 2D Fourier Transform operation!

Wow! Nice vid! Still remember trying many different methods of blooming during the fixed function pipeline days. Had to use a downsampled view so that we get 60 fps using a software blur. Then just combine them with additive blend. Thresholding was also done by averaging RGB channels together then checking if they pass the threshold. All these were done in a 1/2 and 1/4 downsampled view so the effect wasn't as good as what we get these days with shaders. There was also a pure hardware technique(making use of hardware downsampling for free) but you don't get thesholds and the result was blocky at best. Or maybe it was just my 64 mb nvidia mx400.

This one was great, thnx so much!

I was starving for your videos. Your way of explaining is so exciting and concise. Sometimes I think I would try to get a job in Google after watching this :). Please, keep going.

Great break-down. I had to figure all of this out the hard way/over a long period of time heh

I do believe you are one of the best channels here :)

Great video as always. Can you imagine to make a video about half/quater resolution bilateral upsampling techniques? I think rendering stuff into low resoltuion passes became super important in the last years but the culprit always lays in a proper upsampling step pass imo (i think of half/quater res SSR, AO, Volumetrics etc. to full-res upsampling while preserving details from full-res pass). Thanks anyway

My technical understanding doesn't get everything ofc but nice video! Now let me go into bed, replay the video and close my eyes

8:04 that grid is a Hermann grid illusion!

i absolutely love your choice of program in the first terminal animation

Congrats with 100k!

Looking forward to the moment bloom-effects in three-js are doable in a simple manner. It is such a powerful and common tool, so hope it will be possible soon :)

“Until next time, cheers” … Thought I was watching Sebastian for a sec 😂

Excellent video

Hey Man, I really enjoy your videos. Always super exciting to see on my recommended. Truly some gems of videos in RU-vid. Just a suggestion take it or leave it: Way out of my domain but I was looking into volumetric lighting in smoke and stuff. I was thinking it would be a cool challenge to try to make some realistic smoke (not fog, I mean visible smoke that drifts from a point like a particle system) that interacts well with light. Either with volumetrics, particles, or other techniques. Something I’ve been wondering about for a while.

Came for Oyster smiling, stayed for the rest of the explanation.

Thank you, that was really interesting. I use a free Java gauss filter to bloom and it takes 1 second to render a 1/24th of a second frame. I reeeeeeeally need to speed that baby up ...

this is getting a very good channel

10:30 Fourier Transformation has huge implications trough out many fields, once you get a hang of it you will start to see/use it everywhere :)

Oh my god! The amount of valuable information i learned in just 13 mins is just amazing! Thanks Simon!

Streaking is achievable by attaching by attaching a billboard sprite to the light source. It is not always gonna be accurate to the light source those streaks are supposed to represent, but it does its job well enough for 80% of light sources. One of the reasons why I love Unreal 1 and most of UE1 games is those billboard flares. Though if we are on the path of moving away from rasterization tricks and towards more accurate models, I welcome the FFT approach as something representing the real life better

Regarding the last part about using a Fourier transform, @angethegreat did a great video going into more detail for those interested (video titled “What is bloom? (And how is it simulated?)”). His channel is also focused on programming, but he goes a little into the physics of why we use a Fourier transform, which is very informative (well, I was satisfied with what I learned at least). (I hope it’s okay to mention other channels in the comments, but given that you shared links to videos about the FFT yourself, I’m going to assume that sharing is caring).

Huge thanks

Omg I love how fft bloom looks

Honestly tho, the bloom in first seen in Unreal was ... _unreal!_ In a good way. Playing that game for the first time was sooooo epic! It was so much cool stuff to discover, and you completely forgot you were in a game. Instead you were in another world.

Bloom, always loved it even when everybody hated it, thanks a lot

5:13 The one on the right is a game called "Syndicate" released in 2012, not "mid-2000's". But yeah, they really cranked that shit up. 😆

Thank you

finna add the trollface to my convolution bloom effect

I really like this. Probably will never use it. Kinda of like watching a car mechanic fix a car. It's calming. And I can give some comments, like, "hey nice bloom tut there!" But that's about it! :D

very interesting thank you

damn so you could recreate astigmatism with that convolution bloom method

perfect timing as i was planning to revamp bloom in my engine soon

Warframe came to my mind when blooming effect mentioned And you just pulled some footage of it 😝🤣🤣🤣

Very interesting video! Some actual numbers on the convolution bloom would have been great. Is that currently feasible at all in games, or not?

Now it is springtime, and everything is in bloom! Was TRON was the first movie to do the bloom effect? What algorithm did Disney use, I wonder?

This was awesome to hear. I've always wanted to be a game developer because you can bury yourself in making algorithms like this for seemingly simple functions.

Modern GPUs contain fast fixed-function hardware to compute some version of FFT, and inverse too. That hardware is JPEG, h.264 and h.265 codecs. I wonder would it be possible to abuse these pieces of hardware for the bloom?

Hello, I really love your channel and your content. I have enrolled in your shader course and I really enjoy it! I have one question that is bothering me for quite some time when I watch your videos And I really mean no offense by it! Do you use a computer voice when recording your videos? I guess in this time and age it must not be unlikley. Either way, thank you for your educational efforts!

Great explanation. In my game engine I have done something in between I guess. I created a mip chain of the main framebuffer. Blur all these mips with gaussian blur and compose them back. I am satisfied with it, thought one big flaw is pulsing. I have some demonstration of my bloom results on my channel.

I kinda expected a video describing the phenoma of bloom in the real world instead of a video describing how its usually implemented in video games. Knowing how it works in the real world would certainly help making it look more convincing. I turn effects like this off whenever I can, especially considering my eyes and glasses are already doing it with zero performance impact.

My life has something I call the gloom effect TwT

Now BLOOM I can get into!

I think UE's layered thing is mainly to approach the exponentiality of light decay ergo bloom. Blurred plus'd bloom looks weird because there is no proper light decay. I think. I'm a compositor not a gamedev lol.

i'm curious if there's some way to (mathematically/arithmetically) simplify the fourier -> multiply by specific frequency-space texture -> inverse process to maybe make it a little faster for some specific filter. especially when you're multiplying by 0 in a bunch of places, but sadly i do not actually have to math chops to poke at that any time soon.

Simon's secret is that he's redoing the Prototype game using only bloom.

On the other hand, doing an FFT is intriguing for some reason. I think I'll do it one day, maybe in Python, for reasons. Maybe make a competitor to Melodyne, bcos he needs a competitor!11

I wonder if you can use the VK_KHR_cooperative_matrix extension or HLSL ShaderModel 6.0 to speed up FFT transform.

Lol now we can simulate driving at night with astigmatism

Wow cool

Awesome video! How does the Source2 engine handle it though? Games made with the source engine always seem so timeless (portal 2 for example), when you remove the lighting it looks very old but with lighting it still looks quite modern. I'm guessing this is partially due to suttle bloom effects but i'm not sure.

9:24 yet another reason I seem to prefer unity over unreal. The bloom effect from Unity is more subtle and makes more sense, but unreal is just another iteration on the old style. But in general I just prefer C# to C++ and blueprints. And the way that unity deals with components compared to unreal's version. I really wish it was easier to find a unity job.

Hah, there are three settings I disable in any game. Bloom, motion blur and maybe the depth of field. Rarely do I see good implementations of bloom :D

Interestingly the frequency transform is a similar technique to how JPEGs are compressed.

tip for pronouncing romanized japanese names or words: the vowels are always pronounced only one way. "a" is always "ah", "e" is always "eh" (like "send"), "i" is always "ee" (like "seen", same way you'd read an i in spanish). so the name "kawase" is "kah wah seh". it's respectful to double check this stuff before misreading someone's name, ideally.

The first thing I do when I download a new game… is disable bloom and turn off motion blur

"the dark ages" oh man....I feel old, lol

Bloom reminds me so much of the PS3. PS3 games also have a specific dithering in their shadows or in transparent stuff. I'm not sure what it is? You can see it in the animated menu as well.

Love your content and this video, but what do you mean that there isn't a correct way of doing it? Imo you need linear space, where you could take a threshold that would be "maximal capacity of the capturing sensor", take what is over that and "bloom" it in a way that simply spreads said overflowing values around (with some loss of energy), no? (Performance aside :D ) IMO the issue is the fact that we are using blur for it, because that doesn't really capture the lightbleed effect of IRL bloom.

All of that work to get it nice and efficient and as nice looking as possible and the user clicks a checkbox to turn it off because they don't like the look of it. :)

Holy crap, am I the only one who believed the image was of a man picking up rice in a field? Took me like 5 minutes into the video to figure

I always thought games render the frames twice, with normal brightness and lower brightness (say factor 2) and then use a threshold of 50% on the darker frame to get the parts which are brighter than 100% on the normal frame to calculate the bloom. For the darker frame you could also render it in a lower resolution. 🤔

Is it worth doing the FFT and using the results for multiple effects before combining them?

I thought about it randomly and came here to comment this. Isn't it true that by FFTing the image you could combine a bunch of FFT-able effects in one go? (like how you can multiply transformation matrices and apply them all at once). Say, a sharpen effect, and a bloom effect, all from a single FFT round trip. Dunno what else, but probably something!

it seems the convolution with a texture can be easily recreated with a good flare effect, isn't it? with cheap cost. In my game, I find some good flare effect adds better variation, feels more alive than trying too hard on bloom effect.