Partial chromatic adaptation

Software darktable
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The color calibration module tries to guess what color the light is, and transform the scene as it would look if that light were white. But the eye/brain only mostly does that. Incandescent lights still look yellow. Overcast days still look whiter than sunny afternoons.

I’ve been thinking about how to better render these scenes with indoor lighting. I want incandescent lighting to incandesce a bit.

Strategy 1: using the new workflow (although because I have a Sony I need to use a manually created 6500K WB preset), the default “color calibration” module looks somewhat balanced after “reset”. I think it might be reading metadata to fairly similar to “as captured”. It’s not ideal because it can’t be scaled back or increased. (I can reduce the opacity of the CC module or decrease the chroma of the lights. I’m not sure those give the right result. Reducing the opacity definitely doesn’t, but it looks fine in some photos.)

Strategy 2: I think the documentation implied I could use WB+CC as usual, then shift the color temperature a little bit in WB. That seems to look good, but it turns neon lights black. I guess it pushes them way out of gamut. Plus, the resulting image looks more creamy than yellow.

Strategy 3, and this one works: correct the illuminant to completely white (using the color picker or manual adjustment)

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image579×243 44.1 KB

Then click “area color mapping”, open the “correction” dropdown menu. Use the color picker to get a white sample if the input sample is still unset, and change the target from grey to yellow. Set the hue around 70-80 degrees. Set the lightness based on how bright the target is. (A grey card would be ~18%. A white wall might be 80%. These are guesses.) Then set the chroma to decide how yellow the scene should be.
image
image531×505 82.4 KB

These settings are sticky, so it’s important to reset them afterwards. You must change the mode from “correction” to “measure” so your changes have no effect. Then you can double click each of the sliders to reset the values to 50%, 0, 0.

I guess if the scene didn’t have any white surface, I would open the “measure” mode, get any sample with the color picker, then go into the “correction” mode and rotate the hue slightly, and probably add some chroma.

If you have a strategy that works, I’d like to hear how you get good white balance when you want the scene to remain lit as we saw it, not perfectly white.

Note again that my white balance has a custom value for 6500-ish K, and that’s set in the sidecar. These files are licensed Creative Commons, By-Attribution, Share-Alike.
Here’s the JPG straight from camera, showing that the camera agrees with me. The light should be yellow:

pr_SIU01883
pr_SIU018831920×1280 336 KB

The raw and my 6500K white balance:
SIU01883.ARW (23.7 MB)
SIU01883.ARW.xmp (11.9 KB)

Oh, and a tip I got from one of Boris’s videos is to turn up vibrance in color balance RGB right away, since you will better see what colors you’re dealing with.

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You’re going all “Barry Lyndon” on us… :laughing:

Really, I like that thinking. Tungsten and other ‘warmer’ lighting is missing energy in the lower wavelengths, but we want to drive all that to some neutral interpretation of white. 'Specially when the light sources are in the scene like your image, I think ‘warmer’ is ‘better’.

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It would be interesting to share one of your images as a playraw to test out your suggestion.

For myself sometimes, but rarely, I turn of the CC module and just use WB module. Color temperature sliders are intuitive to photographers because we have grown up with the concept.

Sometimes I want to use the picker in the CC module to set the white balance to a target but I find the correction too strong. The simplest solution I have found is to create a second instance of CC, use the picker and then adjust the opacity slider to get the desired correction.

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For whatever reason, my brain says it read/heard that you were supposed to “correct” the adaptation after the fact with other tools or instances of color calibration. On the few occasions that I feel up to this task I use color balance rgb (or just another color cal). Anyway, here is one that i slapped together based on the embedded jpg. I did not go for a full edit, just roughed in the colors. I am sure others can/will do much better work…mine went a little too red (i think).

SIU01883
SIU018831615×1080 330 KB

SIU01883.ARW.xmp (12.4 KB)

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Sometimes I just change “Custom” to “Daylight,” to get a nice “temperature” slider as the simplest way to warm up a picture.

Mostly, that works. Occasionally, I get a colour cast that doesn’t look right, so I back to “custom” and move the chroma slider left. This works, as the Hue is, in my pics, usually at the warm end.

Or… there’s the 4-ways tab of CB-RGB.

But I’m feeling my way in all these methods.

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You can select custom as the illuminant and then adjust hue and chroma as needed to get the look you want.

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Are you sure these are incandescent lights and not LEDs?

SIU01883
SIU018831615×1080 117 KB

SIU01883.ARW.xmp (10.3 KB)

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Thanks, I look forward to trying everyone’s suggestions when I get home! The real test is that it look good on the scene (no green or magenta cast, even with Sony raws), and that skin not be turned into an inappropriate shade.

@Thomas_Do the lights are either incan or yellow orange LEDs but I’d have to go back and feel one to be sure. Some venues definitely still use incandescent bulbs, but probably not as the only light source.

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There are a number of different phosphor combinations in LED’s these days, leading to differing emissions spectra even within a nominal designation such as “warm.” I think color calibration is difficult with such variety.

So I usually start with “as shot in camera” and then try different illuminants and color temperatures. Sometimes I’ll rotate primaries a bit with rgb primaries or lately with AgX. This starts with CC “as shot in camera.”

SIU01883
SIU018832048×1368 399 KB

SIU01883.arw.xmp (9.2 KB)

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I might be missing the whole point of this… But I almost never try to make it look like the scene was illuminated by white.

Disclosure: I primarily do couples/families photoshoots.

When I shoot, I try to pick a white balance that matches the way the scene looks.

In darktable, I just take the illuminant temperature slider and adjust the temp until it looks nice. If it looks odd for any reason, I try “as shot…” and sometimes that helps. By “nice” I mean that I want it to generally look like the actual memory I have of the scene, PLUS the proper emotion/look I want. I know that is not super clear cut.

The only time I try to get something to look accurate as far as it’s color is when I am shooting something like a wedding, where the color of the dress is actually important.

I’m not so laying that anyone should do it this way, but I wanted to know if anyone does it this way too.

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In the film days one could buy color film adjusted for tungsten lighting. The idea was that human vision adjusts to the lower color temperature, and a yellow cast was often not desired.

As mentioned lighting is more complicated these days.

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You can reduce the ‘chroma’ value in CC.

Also, you can try adding a parametric mask, so it mostly affects shadows and mid-tones, and has less of and effect on highlights. An article I found (and lost) demonstrated such double WB treatment, saying light sources look most natural to us if they are white balanced using daylight as reference, which is exactly what happens in the pipeline with the WB + CC method (the pipeline uses the ‘wrong’ (daylight) white balance between input color profile and color calibration, and chromatic adaption is performed only in the latter). The article was about night photography, so light sources would be company signs, traffic lamps, car taillights etc. It’s worth a try.

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I think that’s more or less the same method I posted a while ago:

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Thank you! I’ve been trying to find that post. My idea is a variation on yours. You are attenuating the correction but (in strategy 3) I’m manually filling in the correct right lighting color.

I wish these strategies could be applied manually, without the color picker. The color picker doesn’t work if the scene colors aren’t suitable, and I don’t think it plays nice with calibration presets (wipes out the channel values?)

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I look forward to trying option 3.

Normally I just use opacity to reduce correction when I want to retain some of the original light colour. When I want to manually warm up or cool down the image, I use the first instance of CC to neutralise the image and a second set to black body to adjust to a warmth that I’m targetting. That also works if I’m trying to match the look of a set of images as I can apply the same offset to a whole set after individually correcting them to white.

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Thanks for showing me how. Btw, you can’t use another CC for doing CC, but you can for channel mixing. That would work too, but it seems like it would be easier to introduce errors.

Oh, thanks. I didn’t even know about this. It looks different than the camera WB but I’m not sure what causes it. It seems like a good place to start if the channel mixing just needs some correction. Do you notice a difference versus using the WB module only?

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I never touch the WB module. It’s there as I understand for the benefit of the demosaic module.

There are threads on this site regarding confusion over the use of these two modules. And sure, you CAN use it to edit your photos, but you already have the CC module for that. My take, anyway.

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I wasnt very clear. I had some rather peculiar editing in mind (where the subject and background have different “white”), I shouldnt have mentioned it. It was on my brain and came out with my stream of consciousness writing.

Technically, you can apply another round and just adjust hue/choma…but at that point my guess is that you are just undoing the first instance and it would be better just to do some of the above recommendations.

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Near the end of this article which walks through the nuance of using CC …AP suggests one method for creating artistic adjustments by using the power sliders of RGB CB module. He was a big proponent of not using “wb” for artistic adjustments

Ansel | White balance(s) Ansel | White balance(s)

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Thank you, Todd.

After reading this (and also the manual, which is very good), I’m going to try a new procedure: 1. As shot in camera (as before), then 2) custom illuminant, which has hue and chroma sliders. If “as shot” looks close then adjustments in custom will be just tweaks. Starting with custom and the picker has given me mixed results, but hopefully the two-step process will be more useful.

And, sigh, I might want to invest in a color chart.

Edit: I can get a little closer to your JPEG using this method. As with color temperature, it helps to think of the color of the illuminant and not the photo itself.

Also, whenever I “lost my way” moving the hue and chroma sliders, I’d just go back to step 1 and start over. I’m not saying this is a general method - for that see the manual. But for me the “as shot” is usually a good starting point.

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