How I may implememt some simple "bloom" effect on Natron?

I come from Krita (still I am using it to animate some short sequence, then I use Natron to build bigger things)

On Krita you have filters like the Cross-Channel Adjust Filter to (for example) turn lightness to alpha using a curve:

I combine that filter with a Gaussian Blur to produce some basic Bloom effect

Since I discovered that Natron is much more efficient on handling frame information and massive image filtering compared to Krita (Krita is mainly oriented to be a poweful illustration software rather than complex animation tool) and also my workflow needs to combine image sequence sources on Natron, I stopped the application of Bloom from Krita and now I am trying to do the same on Natron

AFAIK, Natron offers lot of nodes that are supposed to be some “Bloom” filter or similar:

  • Under “Filter => Bloom”
  • Under “GMIC => Degradations => G’MIC Blur Bloom”
  • Under “GMIC => Artistic => G’MIC Highlight Bloom”

And also there is some shader called HDR Bloom, it seems more or less like the thing I was looking for but (perhaps it’s just my case) the shadertoy is very unstable and lead to easy crashes

What I am actually searching for is some way to build the same bloom I was using before, using nodes/filters/plugins on Natron (like for example, turning the dark pixels into alpha using some node before applying gaussian blur to the result)


Using some plugin that applies that simple bloom (just like some threshold plus a blur or something)

I hope my question is clear, otherwise I can provide visual samples


We have several plugins available on

Maybe you can find something there.

We also have an app to manage them (still wip):

I will keep all those, actually the bloom effects are very impressive. I just was looking to have more “control” on the specifics.

All those shader gave me some idea, I can use the shadertoy to do the basic manipulation on color channels I was looking for! :smile:

Like for example, updating the alpha channel according the lightness or some other thing should be more or less easy using GLSL

Once I get how to update the channels, I can combine some other nodes like the blur or gaussian blur to complete the effect.

This was some awesome brainstorming, thanks!

I am having some issues with shaders (the basic testing thing, just sending some fixed color to the output).

I don’t know if I should create a separated topic for that specific thing, or explaining my issue here

Wait, output alpha channel (different from 1.0) from a shader on shadertoy is not currently supported according the official documentation of shadertoy node (it produce unwanted/unexpected results), I will have to rethink this, but perhaps I have the pieces I needed to build what I want