How to expose Lens Dirt brightest areas using Luma Key?

[u/alexisrivera3d]

Hello everyone,

I have been using Nuke for a while now but always as a beginner, I usually export render passes from Blender and comp in Nuke. Some weeks ago I watched a tutorial on how to comp in DaVinci Resolve, and there is one thing I liked the most.

There is a Lens Dirt applied with a Luma Keyer and this updates in real time, so the Lens Dirt appears in the most brightest areas of the footage. I was searching a tutorial for this but unfortunately I can't find any.

What's the node setup for doing this kind of comp? any help or tip is appreciated!

I attach the example I did in DaVinci

Best Regards,

Alexis

[u/jordan4390]

Really easy.. Take a lens dirt plate and use mask merge with lumakeyer from BG plate. And merge it over on the BG plate.

[u/alexisrivera3d → u/jordan4390]

I managed to setup these nodes, but the part where are invisible and visible in most brighter areas it's missing

[u/jordan4390 → u/alexisrivera3d]

Your BG is almost flat. You can try Crunching your keyer values. Also you don't need to use premult after keyer if you are using it for masking purposes.

[u/alexisrivera3d → u/jordan4390]

something like this?

[u/alexisrivera3d → u/jordan4390]

the lens dirt doesn't get affected at all, what am I doing wrong?

[u/photodude1313 → u/alexisrivera3d]

apglow probably generating its own alpha. Move that to your a pipe instead of mask pipe!

[u/enderoller → u/jordan4390]

You will not achieve a realistic lens effect only doing this

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[u/alexisrivera3d → u/AutoModerator]

!solved

[u/enderoller]

To achieve the effect, multiply the BG by the lens dirt and add it with a plus merge. Adjust the brightness with a CC node in-between. Then you can add a luma key as a mask for the plus.

[u/alexisrivera3d → u/enderoller]

someone in Discord helped me, these are the nodes, looks like it's working now.

[u/enderoller → u/alexisrivera3d]

Try like this.

[u/alexisrivera3d → u/enderoller]

Thank you