Firefly Removal

Every modern renderer has to deal with fireflies (very bright, nervously jumping around pixels). Sometimes it’s quite difficult to get rid of those and often enough very high sampling just isn’t an option within tight deadlines.

Most renderers provide a clamping option for that reason. This may work well, but the problem is, that it’s baked in. You are not able to tweak your blur/noise trade-off afterwards. And when your rendering lacks dynamic range because of an aggressive clamp or even worse, stil has fireflies, then you are lost.

Well, not anymore. May I introduce you to my firefly killer gizmo?

Just pipe it in your nuke script and you are ready to go. Now you are even able to only filter a certain framebuffer, too (not possible with built-in renderer clamps solutions). Use gain and gamma to make the fireflies more visible, so that the gizmo is able to find and remove them. You can turn on diagnose  to see exactly what you are doing. Be careful with the pixel size knob. If your fireflies are only 1×1 pixel, set it to 1 accordingly. If you have larger fireflies, you can increase it of course. It’s even perfectly possible to combine multiple firefly killers. That way I was able to shrink a 3×3 pixel firefly to a 1×1 and eliminate it afterwards with a second firefly killer.

A somewhat extreme case: 1 min iray sampling. Note how beautifully all the details and noise is preserved and only the fireflies are removed. (click to enlarge)


Of course everything works great with teapots, so here is a real world scenario as well smile


Download FireflyKiller Gizmo

Happy compositing!






11 responses to “Firefly Removal”

  1. Aaron Avatar

    Great tool mate, and here I was using rotopaint!

  2. stefan Avatar

    Thank you smile
    I’m glad to hear it’s useful.

  3. Rich Frost Avatar

    This is excellent, thank you for sharing such a useful gizmo.

  4. Gael Avatar

    Just great!

  5. Paul Avatar

    Thanks a lot. You save my time hugely!!

  6. stefan Avatar

    Hey everybody! Thank you all for the nice comments! smile I’m looking into ways to improve this even further. Maybe I find some time to update firefly killer and put it on nukepedia, so that more people get to know it.

  7. Sergio Avatar

    Stefan, you’re a legend! Just what I was looking for, thank you!

  8. Julie Joannotéguy Avatar
    Julie Joannotéguy

    Thanks you so much, it’s so easy to set and saved me from trouble with my comp. I had pretty bright blue dots on a lot of places and with 3 pixels large ! With two of your nodes I was able to remove all of them ! So glad I’ve found this tool.
    Thanks, thanks, thanks, thanks. smile

  9. YVLON Avatar


  10. clinton Avatar

    Yep, legend! While we have in-render denoise functionality as standard these days, this is still the ticket in some instances.

    Thanks for sharing!

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