Problem with spotlights

Hello. I did several pictures of concerts and i have a problem with the red or blue spotlights: there are artefacts around them. I try the different color profiles in the ICM module but it doesn’t change anything.

Try turning off sharpening if it’s enabled

The sharpening module is off. I try with darktable and there’s the same problem: I deduce this is not a software problem but it’s inherent at the LED spotlights. I’ll try to find a workaround.

Try this profile:

Nikon_D750_dcamprof.icc (212.5 KB)

It’s a LUT profile based on SSF data from the OpenFilmTools project.


Thanks for this but that does not help things. But, your idea is good: i try with the "Rec709.icc profile and it works quite good. This profile darkens a bit the picture but it can be corrected quite easily with the tone equalizer.

Try gamut compression in DT in color calibration module…also Aurelien has a couple of videos where he addresses the LED light issues…he also uses a channel mixer tweak in one of them as well I believe…

The profile I posted is intended to be used as an input (camera) profile - did you use it there?

Thank you. It works quite fine, with input and working profile set to linear Rec2020 RGB profile in the input color module. Damn, i don’t want to change software again!


If you share the raw file I can take a look and tell you whether you can avoid the artifacts while staying in ART (assuming you are interested of course – I don’t want to discourage anyone from using something else of course!)

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Using linear Rec2020 for the input profile might look okay, but that profile was not designed to represent your camera’s spectral response. The profile I posted was created from D750 spectral measurements, and it does the color transform with a LUT instead of a matrix, which provides better information with which to do the gamut crunch.



  • If you don’t mind, your photo is a good candidate for playraw.

  • in june 21, I made photos with a Z50 from the end year show of my granddaughter dance school. I it’s usual now they had a lot of spotlights with harsh red, blue and green spotlights.
    Developped with ART.

  • No real problem except with blue that had to be tamed with the ACES channel mixer trick (
    This trick is superseded by the ACES gamut compression transform.
    from ACES:

The gamut compression replaces the simple and less robust LMT.Academy.BlueLightArtifactFix.ctl. The ACES gamut compression transform has numerous advantages over the BlueLightArtifactFix LMT

@Age also produced a desaturation channel mixer matrix that can be useful.

Note: I cannot share as I was asked by the school not to share on web.


@agriggio @gaaned92 Here’s the NEF file
_DSC1932.NEF (20.9 MB)

Yes, thank you. Here’s the result: it’s better but there are some artefacts yet.

Yeah, same sort of thing I get taming blue LED spots, better but not perfect. There are ways to tune the production of the camera profile for specific situations; if you do this a lot, it might be worth exploring the use of dcamprof or its not-free GUI brother, LumaRiver.

I’m not that familiar with them, but recent darktable apparently has some really good color correction tools, which might work as manipulations before the color transform to the destination gamut.

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Thanks. Would this be acceptable?

What I did:

  • start from the “Auto-Matched Curve” default profile (just because)
  • switch “highlight reconstruction” to “color propagation”
  • Enable “channel mixer”, set it in “primaries correction” mode, dial down the red saturation (I used -61) and tweak the red hue correction (I used +15) depending on taste.

Hope this helps…


Thanks. It helps me. I did what you advised me, with the ICC profile of @ggbutcher and several other minor settings and thats’s the result and the .arp file.

_DSC1932-2.jpg.out.arp (11.1 KB)


@ggbutcher @gaaned92 @priort @agriggio Thanks a lot for your help and advices!
Color propagation in highlight reconstruction module and D750 dcamprof.icc profile seems to be the good tools to reabsorb these artefacts.

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A simple edit using darktable, with 2 instances of color calibration: one excluding the reds, the other using an inverted raster mask to target exactly those regions. I didn’t fiddle with any other settings. I’m not sure what artefacts you want to eliminate. For me, the toned-down highlights (such as around the lamps, and on the bottom right) look too compressed in Problem with spotlights - #14 by Mickabail.

If someone think it could be interesting i can share this image for playraw, neutral profile in art here:

sure, feel free to post it!