Vignette in VFB

[JonasNöll]

Hi,

not sure if it was mentioned before,
but would be cool to have controls for vignette in the VFB.
In the camera you often times can't get the desired effect because the vignette varies with FocalLength and is also affected by DOF.
So if there would be something similar like the Sharpen/Blur as a separate category for adding a vignette with some parameters like defining the vignette gradient, the center of the vignette and so on. That would be awesome.

There is some complicated workarounds how you still can do it in the Composite involving the ExtraTexture and a Gradient ramp, but it's not practical...

[sirio76]

A while back I’ve posted a trick to do that easily, I’ll se if I find the topic.

[sirio76]

Here it is:
https://forums.chaos.com/forum/v-ray...77#post1136177
it works decently, of course a dedicated tool with proper control would be better

[JonasNöll]

Hi, awesome, that really kind of works. I was doing it a way more complex using a ExtraTexture Renderelement and then loading a radial Gradient Ramp in Screen mode inside. And then multiplying that renderelement in a VFB composite before the tonemapping. It works but IPR always needs to wait for the renderelment to generate in order to see it.
With the background image and the 32bit image thats definitely a better solution! Thx

[sirio76]

You are welcome
If needed I can upload the file

[JonasNöll]

Bumping this to hopefully be integrated in the next update. After we got chromatic abberation now in the latest update 2, vignette would make a nice addition in the Lens Effects Tab of the VFB
And while we are at it some film grain would also fit well in there

[seandunderdale]

Bumping for visibility. I second vignette and noise!

[piotrus3333]

vignette via Background layer should be applied in Composite part of the stack with multiply operator to look correct.

regarding film grain - why not use film grain overlays? real grain will always look better. tools are there within VFB - no point in overloading it with cheap filters.

[JonasNöll]

Vignette via Background doesn't have to be in a composite, as long as it's happening before the tonemapping. Since the LensEffect happens before the tonemapping that would be a good place to put vignette effects as well.
For FilmGrain it would help to reduce the perfect denoised look. If the denoiseblending is set all the way to 1 it would look more realistic with some subtle noise. Since we already got Chromatic Aberration as a "cheap filter", FilmGrain would just be a logical addition in the LensEffects.

[piotrus3333]

chromatic aberration is so much easier to implement. grain is quite complex.

[piotrus3333]

also adding noise/grain on top of denoised image is probably not the best way to get more organic or natural looking image. the secret is in perfect balance of noise you are already getting from raytracing and AA filter. you can even replace aa filter with post blur effect. mix in a bit of denoising or skip it completely.

and if you are after film grain look specifically - overlays. unless you are expecting Resolve level filters in VFB.

edit: regarding positioning of vignette in the stack - not before tonemapping but before bloom/glare.

[Joelaff]

I would argue some glare occurs after any lens vignetting. It depends on where in the physical lens the internal reflections are happening, but I have seen plenty of footage with real cameras where the flare/glare extends over the image circle, even out into the outer black of a circular fisheye lens for instance.

I don’t like to do too much with the image in the VFB, and never show it to clients, as the images will be post processed in other software, which will never precisely match whatever the VFB would do.

[Pixelcon]

also adding noise/grain on top of denoised image is probably not the best way to get more organic or natural looking image. the secret is in perfect balance of noise you are already getting from raytracing and AA filter. you can even replace aa filter with post blur effect. mix in a bit of denoising or skip it completely.

and if you are after film grain look specifically - overlays. unless you are expecting Resolve level filters in VFB.

edit: regarding positioning of vignette in the stack - not before tonemapping but before bloom/glare.

Hey Marcin,

Are you able to get a grain overlay in the VFB without the denoiser just removing it's effect? If so, can you hint towards a layer-ordering?

[piotrus3333]

Hey Marcin,

Are you able to get a grain overlay in the VFB without the denoiser just removing it's effect? If so, can you hint towards a layer-ordering?

grain overlays would usually come from real film scans - so this would be "on top" of the VFB stack - when pixels are in their "display ready" state, not under the denoiser when pixels are just linear data.

V-Ray: VFB trick or two to emulate film.
here the overlay is just before rec709 transfer function (hence inverse gamma on overlay itself)
today I would probably put it higher if it is just 8bit overlay.

[Pixelcon]

Ahaaaa of course now I see you need to put it inside a folder to access the blending modes. LOGICAL VFB STUFF...
Thanks!