Fantastic piece. I love stuff with interactivity; and the comparison between blur types is great, as your eye can evaluate them side-by-side. Thanks for putting it together!

Good article, but it uses less than ideal formula for weights of the gaussian blur kernel.

Gaussian function for coefficients is fine for large sigmas, but for small blur radius you better integrate properly. Luckily, C++ standard library has std::erf function you gonna need for the proper formula. Here’s more info: https://bartwronski.com/2021/10/31/practical-gaussian-filter...

Great blog post. Kawase rocks! Nice work. Is the interview translated into English anywhere?

I'm a huge Adrian fan boy <3

Yes, bokeh blur is way more pleasing. In my article the gaussian likes are the focus for their use as a basic building block for other effects, like frosted glass, heat distortions, bloom and the like.

Specifically the 2015 Dual Kawase was created in the context of mobile graphics, with weak memory throughput. But even on my RTX 4090, near the fastest consumer hardware available, those unoptimized unseparable, naive gaussian implementations bring it to a crawl and `samplePosMultiplier` has a non insignificant performance hit, so texture caches still play a role.

At today's high resolutions and especially on mobile, we still need smart and optimized algorithms like the dual kawase.

Acerola does some fun projects, but his optimized grass rant was the funniest thing I saw in years. =3

First time hearing this! I added a URL parameter `noJustify`, which removes text-justification. Eg. https://blog.frost.kiwi/dual-kawase/?noJustify

I'm not sure either way, would you say this makes it easier to read and I should make it the default?

Once Multi-Step Downsampling comes into the mix, the image starts to "boil" as it moves. This is especially bad with very strong lights that are small, as the lights seem to appear and disappear with long downsample chains. Most of the recent blur technique evolution centered on fixing this issue, as shown in "Next Generation Post Processing in Call of Duty: Advanced Warfare" at the end of the article.

This is not the first time [1] I hear this critique of movement by default being annoying. Should I just turn it off by default?

[1] https://news.ycombinator.com/item?id=42191709

Do you know what aliasing is in a game? When the edges are too sharp? They can look okay in a still image, but they are really noticeable when things are in motion. Another such example is the moire effect. Moire is very noticeable in still images too, but when moving, it's really noticeable.

These blur effects, like any other graphical thing, can have a similar effect when combined with motion. The animate function is to bring these issues out, if there is any.

These are unrelated techniques.

Spherical Harmonic Lighting is an alternative or used to supplement the generation of HDR cube maps for the purpose of global illumination. For the very diffuse aspect of this global illumination, Spherical Harmonics are used (Often called light probes), as a very cheap approximation of the environment, that is easy to get in and out of shaders and interpolate between them. They are just a bunch of RGB floats, so you can place a ton of them in the environment to capture a scene's direct or indirect lighting. For specular reflections you still have to use HDR cube maps, as the light probes don't hold enough information for that task.

Blurs are a basic building block of image processing and used in a ton of effects. In a way, there are related topics, as the cube maps generated to cover different roughness factors for PBR rendering are, in-fact blurs! https://threejs.org/docs/#api/en/extras/PMREMGenerator But that's not the topic of the article, but instead of how to do blurs efficiently in real time, in the first place.