Author Topic: Alpha is cutting bloom/glare  (Read 1205 times)

2024-03-25, 12:26:28

TeoRossi93

  • Active Users
  • **
  • Posts: 136
    • View Profile
Hi guys!
I have a problem when I try to composite bloom/glare pass in After Effects.
Basically the bloom/glare is not going over areas where there are transparencies, and this is a huge problem.
In the attachment you will se the VFB image that is the correct version. Then you will see the COMP image, done in after effects, that is completely missing the glare (because opacity cuts it).

The background is a stock video of course.

I'm rendering an exr file with all the compositing layers (virtual beauty, bloom/glare).
I still haven't figured out a method to comp this thing properly...

Thanks
Matteo Rossi 3D - https://www.teorossi.it/

2024-03-25, 17:28:22
Reply #1

maru

  • Corona Team
  • Active Users
  • ****
  • Posts: 12805
  • Marcin
    • View Profile
I am not sure how exactly you are compositing your frame, but this should work:
- use beauty without bloom and glare as the base layer
- on top of that load the bloom and glare layer (bloom and glare against black background), make sure that it is loaded without transparency (opaque, alpha is pure white)
- set the bloom and glare layer to "add" mixing operation
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2024-03-25, 17:47:16
Reply #2

TeoRossi93

  • Active Users
  • **
  • Posts: 136
    • View Profile
I am not sure how exactly you are compositing your frame, but this should work:
- use beauty without bloom and glare as the base layer
- on top of that load the bloom and glare layer (bloom and glare against black background), make sure that it is loaded without transparency (opaque, alpha is pure white)
- set the bloom and glare layer to "add" mixing operation

Hi Marcin,

the problem is not how I compose the file, the problem is that the bloom/glare is "limited" inside the objects shape, it's not spreading outside if I keep the alpha activated.
In the attached image you will see how the pass is looking, the white spot should be a glare.
Matteo Rossi 3D - https://www.teorossi.it/

2024-03-25, 17:50:02
Reply #3

maru

  • Corona Team
  • Active Users
  • ****
  • Posts: 12805
  • Marcin
    • View Profile
Is this the bloom and glare pass saved from Corona VFB?
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2024-03-25, 17:52:57
Reply #4

TeoRossi93

  • Active Users
  • **
  • Posts: 136
    • View Profile
Is this the bloom and glare pass saved from Corona VFB?
Nope, this is a multilayer exr file that I'm saving as multipass and extracting it using extractor in after effects.
Since this is an animation I can't save the bloom pass by hand for each frame😅
Matteo Rossi 3D - https://www.teorossi.it/

2024-03-25, 19:28:09
Reply #5

pokoy

  • Active Users
  • **
  • Posts: 1874
    • View Profile

...
...it's not spreading outside if I keep the alpha activated.
...
[/quote]
If there's image pixels saved in areas where alpha=0 it means you can still duplicate the layer with only glare&bloom visible, put it in top, disable alpha for that layer only - wouldn't that work?

2024-03-25, 21:07:08
Reply #6

TeoRossi93

  • Active Users
  • **
  • Posts: 136
    • View Profile

...
...it's not spreading outside if I keep the alpha activated.
...
If there's image pixels saved in areas where alpha=0 it means you can still duplicate the layer with only glare&bloom visible, put it in top, disable alpha for that layer only - wouldn't that work?
[/quote]

Sorry, I don't get you. How can I turn off alpha just for bloom/glare pass?
Matteo Rossi 3D - https://www.teorossi.it/

2024-03-26, 07:00:41
Reply #7

bnji

  • Corona Team
  • Active Users
  • ****
  • Posts: 213
  • Benjamin
    • View Profile
    • Corona Renderer
Hello @TeoRossi93, I think @pokoy may be right...
In AE, you can define whether if an image sequence will use the Alpha channel or if it should be ignored and interpreted as a solid alpha channel.
Just set the image sequence to use a solid alpha channel, then proceed as @maru suggested to composite the layer using the "add" mode for blending the layer.
I hope this helps.
Please let us know the outcome.
Have an amazing day/evening.
« Last Edit: 2024-03-26, 08:14:16 by Beanzvision »
Benjamin Rosas | chaos-corona.com
3D Support Specialist - Corona | contact us
Corona Uploader l Upload

2024-03-26, 10:50:36
Reply #8

TeoRossi93

  • Active Users
  • **
  • Posts: 136
    • View Profile
Sorry guys, maybe I can't explain properly what my problem is...
Please, look carefully at the images that I'm attaching here.
As you will see the glare is completely missing in the pass, how am I supposed to composite it if it's totally missing?

I'm attaching even the exr multilayer file so you will understand better the issue
Matteo Rossi 3D - https://www.teorossi.it/

2024-03-26, 11:16:13
Reply #9

pokoy

  • Active Users
  • **
  • Posts: 1874
    • View Profile
Here you go, AE file (v2021) and a Screenshot attached.
Disregard the background, it's just a random gradient to help seeing the result.

In AE, you can tell a layer (file input, whatever) to use its own alpha, another layer's or file's alpha, or any arbitrary alpha channel, by using one of the Matte effects on it.
To make it work you need to:
- set the original base layer (your beauty) to use the file alpha (done automatically by EXtractoR) - that's what you probably did already
- duplicate that layer, set EXtractoR to use the bloom&glare channel
- with that layer selected, add a 'Set Matte' effect
- in the 'Set Matte' effect UI, set matte to 'full color' or 'plain color' (I'm using a german OS so no idea what it's called in english)

Now you've effectively told that layer to use a fully white mask instead the one in the original EXR file.

2024-03-26, 12:50:42
Reply #10

TeoRossi93

  • Active Users
  • **
  • Posts: 136
    • View Profile
Here you go, AE file (v2021) and a Screenshot attached.
Disregard the background, it's just a random gradient to help seeing the result.

In AE, you can tell a layer (file input, whatever) to use its own alpha, another layer's or file's alpha, or any arbitrary alpha channel, by using one of the Matte effects on it.
To make it work you need to:
- set the original base layer (your beauty) to use the file alpha (done automatically by EXtractoR) - that's what you probably did already
- duplicate that layer, set EXtractoR to use the bloom&glare channel
- with that layer selected, add a 'Set Matte' effect
- in the 'Set Matte' effect UI, set matte to 'full color' or 'plain color' (I'm using a german OS so no idea what it's called in english)

Now you've effectively told that layer to use a fully white mask instead the one in the original EXR file.

Alright, sorry. I didn't know that thing.
I'm not sure which is the parameter to tweak tho, in the Set Matte effect. Now I applied it to the bloom layer, with the extractor too of course
Matteo Rossi 3D - https://www.teorossi.it/

2024-03-26, 13:52:49
Reply #11

pokoy

  • Active Users
  • **
  • Posts: 1874
    • View Profile
It's 'Use for Matte' - full/plain color or no color, either will work, one of them needs to be inverted (depending on whether it produces full white or black).
When you set the layer to add (or screen if you're not working in linear mode) you will see immediately which one is producing the right output.

2024-03-26, 14:41:45
Reply #12

TeoRossi93

  • Active Users
  • **
  • Posts: 136
    • View Profile
It's 'Use for Matte' - full/plain color or no color, either will work, one of them needs to be inverted (depending on whether it produces full white or black).
When you set the layer to add (or screen if you're not working in linear mode) you will see immediately which one is producing the right output.
I feel stupid but I can't make it work lol.
Could you send me the AE file that you setup please?
Matteo Rossi 3D - https://www.teorossi.it/

2024-03-26, 14:56:28
Reply #13

pokoy

  • Active Users
  • **
  • Posts: 1874
    • View Profile
Unless I did something wrong the AE file should be attached to my answer above along with the image.

2024-03-26, 15:03:21
Reply #14

TeoRossi93

  • Active Users
  • **
  • Posts: 136
    • View Profile
Unless I did something wrong the AE file should be attached to my answer above along with the image.
Sorry again, I missed it. My brain is melting today🫠
The "set matte" in my AE version was set a bit differently from yours. Now it's working fine :)
Thanks again for the explanation
Matteo Rossi 3D - https://www.teorossi.it/