Oversaturated Blue - Frankfurt Skyline at night

Don’t know too much about .dcp files (for they are not used in dt, which is the only program I’ve been using for raw files). But I guess is more or less the same idea of the video by Aurelien previously posted. But, that’s yet ready to use, most probably, which is comfortable, though Aurelien’s approach gives individualized control using your camera (that can be slightly different fro other similar ones) and even the objective, or exact light conditions.

Anyway, it seems that there is a way of using them in dt, converting them into ICC profiles:

Probably worth trying! I’ll do when I have some time for this, for one of my cameras is supported, and the other is not, but there are other similar that probaly can improve the results.

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I think you’re right. You could raise it as a suggestion here - https://github.com/darktable-org/darktable/issues

If you can, you can install Adobe DNG converter and it has DCP files for most cameras so you can use their version, you can also make dcp profiles with either xrite software if you have the card and software or if you can use dcamprof to make your own calibrated profiles…I think RT has some dcp profiles and some custom profiles that are based on DCP files depending on your camera. With DCP you have the option in color management to tweak parts of it by adding the tone curve or not, the base or look tables as well just to see how it goes…in RT thought the model used for the tone curve can really make a difference if you cycle through the options you will see what I mean…Also if you have the automatch on you will see it changes if you use the dcp profile and depending on whether you use its tone curve or not…

DSCF2202.RAF.xmp (9.7 KB)

Blue hour with ART


It’s not just a DCP profile that makes the difference, it’s what’s in it. I haven’t torn apart the particular profile in play here, but I’ll bet it uses a lookup table (LUT) transform instead of a matrix.

With a matrix transform, all the algorithm knows to do is to deposit out-of-gamut colors just inside the destination gamut, without any concern for giving them some gradation that approximates what they had “out there” in the original space. A well-constructed LUT will provide the information to do just that, approximate a gradation in the destination colorspace.

Making a LUT camera profile takes a bit more information than what you get from a ColorChecker target shot. I’ve tried an IT8 target and the LUT profiles from it work better, but not as well as using spectral data measured from the camera. dcamprof will make LUT-based DCP or ICC profiles from either target shots or spectral data.

The above is just a rehash/synopsis of all the crap I wrote about it here:

  1. https://discuss.pixls.us/t/the-quest-for-good-color-1-spectral-sensitivity-functions-ssfs-and-camera-profiles/18002
  2. https://discuss.pixls.us/t/the-quest-for-good-color-2-spectral-profiles-on-the-cheap/18286
  3. https://discuss.pixls.us/t/the-quest-for-good-color-3-how-close-can-it8-come-to-ssf/18689
  4. https://discuss.pixls.us/t/the-quest-for-good-color-4-the-diffraction-grating-shootout/19984/75

#3 talks about using large-patchnumber targets.


i was wondering when someone would say “spectral input profile”. here’s a vkdt render with a lut constructed from ssf:

(and just to match the other renditions better, here one with crazily pushed saturation, but constrained to rec709):


Ooh, you have ssf data for the Fuji X-t30? If you can share it, I’d like a copy for my collection… :laughing:

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Photoflow + a look with contrast and colourfulness set to ‘too much’ + OpenDRT.
I’m converting everything to ZCAM JzMzhz space for the look - you can do quite extreme things!

Camera profile was whatever matrix Photoflow has built in for the X-t30.


Interesting rendition. It also seems to suffer from the blue problem.

This one looks fine to me. Maybe because it uses the same DCP profiles RT uses?

Maybe someone can help me to extract the proper learning from this. As of now I feel the DCP profile makes the difference, hence RT will give inherently better results than DT. But I’m not quite sure if that explanation is maybe too simple since the vkdt rendering also looked quite good in the blue tones.

DCP are generally dual illuminant between tungsten and D65 and so you can interpolate from these two points …ICC are generally set to D50 WB and so I think a bit less useful outside the range of light from which they are produced than a DCP would be …but some of it is also software…RT lets you apply or disable components of the DCP file ie the base table the look table and the tone curve and also combine this with the auto match curve …so there are lots of options during processing and if you grab the ones from Adobe you can do so from a standardized starting point…RT also has abstract profiles that can be thrown in to the mix…however having said all that Aurelian’s approach to leverage the channel mixer to further tweak an existing profile is a nice tool on the DT side of things…

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Glen back when I was trying to sort out DCP files I found this reference.


They talk about the tables having a third dimension which is often set to 1 ie not used…

Is this the difference in Dcamprof when you go from the 2.5 to 3D Lut versions ie the 3D LUT uses the third dimension and having said that then are these Hue and Color Saturations tables the Luts or are the Dcam Lut profiles a different beast than the standard ones described by the specs… just wondering…

Anders describes it well in the dcamprof doc:


Edit: Oh, are they different from the DCP spec? Dunno, haven’t looked…

I only tried in Art not RT but ART is using a different DCP file which will be used by the automatch profile if that is what you are using. The standard adobe profile also has a look table…you should try snap shots with the default RT or ART profile and compare that with a custom profile and then select the Adobe XT-30 profile…here you will be able to turn the look on and off. I think the look might be something that would impact the overall look and the blues perhaps…I will try later if I get time…if you want to see the difference in the adobe and art DCP files you can look here…json files…had to zip them…just text so easily viewable…you can get the Adobe DCP easily if you wish to test…

XT30art.zip (210.6 KB)


In RT and in general with these blues…change the working profile and look at the affect …rec202 vs Prophoto vs Widegamut vs ACESP0…you might also find some magic here to tame your blues…

Tried to load your edit from the jpg…did you use a lut…looks like you did…

Thanks I’ll take a look at one later and compare…

here I used Adobe DCP

Film simulation seemed to be active