Blur applies bokeh to front and matte :(

[andy_dill]

I fooled around with the various options this evening and made a video:

Defocusing Elements in Flame

the TLDR is most of the methods discussed in this thread are fine but all have shortcomings.

Also, this was a hasty test for blurring a CG-type element, so some things that underperformed here (ex4: convert to aces and blur) work very well in other contexts.

The setup is here (flame2024.2) for anyone interested. I suggest rendering out the particles before messing around.

also, also, because so much of the particle element was semi-transparent, I made a more opaque element and found I had a lot better control over all five options, whereas only the fully-linear version worked well when everything was small and mostly transparent.

here’s a still of the results, with Linearized Fill finally pulling it’s weight:

[andy_dill]

Also, just for a little “scene linear sidebar” here¹, the reason linear gets blooming correct for free is due to the nature of scene linear images. They store real-world values, and anything that is bright is thus astronomically bright. Middle gray is around 0.12 (or 0.18, whatever) and white is up at 10. This means that anything that’s white is going to bloom like crazy naturally while all less-bright colors aren’t going to do much, which is what we see in real life when our cameras don’t focus: big pingy circles where lights should be.

_{1. This isn’t aimed at anyone and i’m probably only typing it due to my giant frustration a decade ago when no one could explain to me why “linear” was “linear” and why it was in any way better than video. They’d always say, “the math works” but they really meant “add works”. The real answer is that it mimics real-world values and thus gives more realistic results for various optical effects, chief among them the defocus. and also, the math works.}

[PeteRypstra]

Y_LENS BLUR all the way. We are having great results with this. It defaults to a gain of 2 by default so I reset this to 1 and then work from there. You can set it to linear or r709 in the last tab. You can change the shapeof the bokeh to match anamorphic or spherical. It works well with depth mattes and if you prremult properly, you can even add chromatic aberrations (in small doses) without any complications.
I can’t remember pushing this with bokeh so I must admit I could be slightly off point here.
When I realty want to push defocus and bokeh, I ask for cg to be broken up into layers and use saphire rack defocus comp.
This also has some simple and really effective controls and does bokeh really beautifully

[BrittCiampa]

Are you thinking y_lensblur by chance? I too use it all the time, but generally just for a really quick and simple dof where I need to generate a hacked depth matte.

[BrittCiampa]

@andy_dill

This isn’t aimed at anyone and i’m probably only typing it due to my giant frustration a decade ago when no one could explain to me why “linear” was “linear” and why it was in any way better than video. They’d always say, “the math works” but they really meant “add works”. The real answer is that it mimics real-world values and thus gives more realistic results for various optical effects, chief among them the defocus. and also, the math works.

I will add here to what Andy’s saying that it gets double frustrating when people get “linear pilled” and don’t want to admit that some operations SHOULDN’T be done in linear space. Sharpening, resizing/ filtering, graphic work, are all either inferior in Linear space or just going to give you an endless headache. I do all my beauty work in log because high pass filtering in linear always gets icky. There’s a time and place for it. Blurs is the best time and you’ll have the bestest time! You can always switch from ACEScg to ACEScc and back again as much as your color managed soul desires. You’re not stuck in a color space ever, however, never ever convert into a more limited gamut of color space and then try to go back, that’s destructive and a bad time.

[PeteRypstra]

Yes! Doh! Thanks I’ve edited that

[GPM]

Also a vote for y lens blur, which I turn to first for both stylistic/creative uses as well as more technical stuff. It’s fast and has a lot of good controls.

[KuleshovEffect]

Every now and then I’ll start to think I kinda know what I’m doing, then @andy_dill casually drops stuff like this in a thread

[DannyYoon]

@philobedo

…de, it applies the blooming on the front but also on the matte which doesn’t make any sense and breaks the Premult workflow…Is there a way to apply the blooming only to the front. (other than blurring before premulting the front and the matte which isn’t always possible for exemple if I receive from 3G an image already premultiplied…Not sure I’m clear enough. Let me know if I can add infos…Thx folks

Hey!

You can use “PunchBack Trans” instead of “Blend” to fix this issue. “PunchBack” will do the same, but making the image transparent does strange stuff, hence the reason for “PunchBack Trans”

You can keep the defocus + bloom on the Fill, and copy that node and on the Matte, set the bloom = 0.

PunchBack Trans, will do the un-multiply correctly and any extra info outside the matte will be an additive.

I also use this for adding glows on CG or Graphics and the glows will show up nicely.

The extra bonus is you don’t need an extra Action layer just for the glow since you baked it in upstream.

When I have a lot of CG elements in a spot…I will bake in glows and bloom on the Fill and bake in shadow mattes in the Alpha. So, instead of 3 layers in action, you only need 1.