This video is a must watch

from:

https://www.youtube.com/c/StudioPetrikas

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I have a difficult time explaining to people my fondness for darktable. This video is a good starting point I can send them, thank you.

What software is he using in the beginning to demonstrate the hue shift?

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Affinity Photo

Brilliant explanation – thanks for sharing!

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I tried to replicate the experiment with the hue shift in few programs…
Lightroom 6 didn’t show this issue.
I was able to replicate the cyan shift in Capture One, ART, Affinity, PS CS6.
I got pink shift in Krita and Luminar3.

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Thanks for the heads up. I had previously passed it by in my feed, but it was worth watching. Looking for insights into the highlight reconstruction module (on by default) and if it’s redundant with filmic. I find that I’ll often either switch off highlight reconstruction, or change it from clip to reconstruct.

There was recently a potential bug or suggestion to blend HR in normal bounded blend mode for a couple of the methods…you could also try that…I think I do recall it was recommended to turn it off if using HR in filmic but I also think there are example where people have said that using LCh reconstruct with it helps… I think this area of DT is being tweaked a bit recently so maybe its also just wait and see on some of these things…

Did you activate tone curve in ART?

Tone curve off:

Tone curve on:



When opening e.g. TIFF, tone curve is off by default. For RAW it’s on and common.

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As one of the younger people here (not that young mind you) this made me realize why those of us that grew up with digital imaging being the norm saw filmic as “wrong” out of the gate. The cyan transition in skies particularly was expected in my images from my experience growing up and when I didn’t get it the first time around it was visually jarring to me. Probably why digital renders try to replicate it too. For a huge chunk of the active under-40 demographic these days hue shift is normal. Maybe people with a stronger art background know about it. I’m far from any kind of engineer, mostly just a tradesman that happens to use PCs a lot.

I have shot a fair amount of color film but really as a curiosity. I didn’t have the vocabulary at the time to articulate why it looked different. Also we mostly scanned the negatives into digital back then so it was kind of lost in translation too.

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You just blew my mind! It’s a good point though, and something that I had never considered before.

Yes, it seems to be harmless most of the time. Here’s some feedback from the author ot the video on that topic:

Right, so I have the “Highlight Reconstruction” module disabled, as I use highlight reconstruction in the “filmic rgb” module, when necessary.
That “Highlight Reconstruction” module is meant for when “filmic rgb” module is not enabled.
It’s better to use highlight reconstruction tab in “filmic rgb” module, when “filmic rgb” module is enabled.
It sounds convoluted, because it is…
To be honest, I was puzzled to why it’s ON by default in the latest Darktable, it shouldn’t be, IMO.

I didn’t watch the video. What is this cyan business about?

Fun fact: my brain did not compute when I saw the word norm. Been using norms in my own processing and reading about norms in dt discussion. It is also past midnight. :full_moon_with_face:

Yeah, sorry, it was without the tone curve.

Interesting. I have not found the reconstruct tab in filmic rgb to be of any use. I have a preset that sets the Highlight reconstruction module to “reconstruct in LCh” mode… automatically and for all images. Otherwise I sometimes have pink skies.

I never do anything else with the HR module, but I make use of the scene tab in filmic. I tried turning off HR, and using only filmic and don’t always get the same results. I can’t get the reconstruct tab in filmic to do anything useful.

I understand you because I had a hard time trying to figure out the best way to recover highlights with filmic rgc.

After watching some videos of Aurélien and reading/learning about the development of the filmic rgb module in this forum I’m now have a way to recover highlights and I’m very satisfied with it.

Basically I deactivate highlight reconstruction altogether, and set preserve chrominance in filmic to ‘no’. After this I go to the reconstruct tab of filmic and adjust the threshold and maybe some of the other sliders. Part of those steps were an advice of @kofa in this thread: Lost highlights in darktable - #2 by kofa

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I don’t think I ever recommended that.
I find that with bright highlights, luminance Y works well. For my taste, ‘no’ results in too much desaturation.
After I made that comment, Aurélien developed his new guided laplacians method for highlight reconstruction. And I still use LCh from time to time.

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I edited my comment, I hope I expressed it better now :wink:

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It’s probably best to watch but he talks about how in typical RAW processing software the highlights in a blue sky shift hue into cyan before heading towards white.

Being a spry, young 30-something hue shifts in digital imagery is what I’ve seem my whole life so I expected and when filmic didn’t do it looked wrong. So much of our expectations and what looks like reality to us is baked in by our culture and the technology of the time. To this day I swear the real sky shifts to cyan near the horizon to my eye except on exceptionally clear days.

As for “the norm,” I just meant it here as “usual” or “expected.” From about my teenage years on digital filming and photography have been everywhere. Even my poor rural high school had one of those floppy disk using Sony Mavicas back then. I didn’t get a personal digital camera until the early to mid 2000s but I was still relatively young and in college at that point.

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My point was the normalization of norm on this forum led my brain to compute it as the mathematical term, just as you tend to expect cyan.

What colour is shifting to cyan? An oddity about me is that I don’t think in colours, so I have difficulty talking about them, if that makes any sense. I need someone to describe it to me.

It is visually described in the video, quite well.