color calibration - Brainblasting...

Is it overexposed? Click the raw overexposed button and see if the magenta highlights are. Change highlight reconstruction to reconstruct in Lch and adjust the slider to get rid of the magenta

After watching the Video: the blown reds turn into magenta (one can see this by turning highlight reconstruction off) and then pushed by color calibration over the whole image. Perhaps sunrise hast to be shot with “expose to right” and massive pushing of shadows. Don’t misunderstand, Aurelian’s thougths and work are great - I would just mention that Rawtherapee produces an acceptable output of that sunrise image out of the box without banding and magenta errors.

if Rawtherapee doesn’t have magenta stuff they might use a different whitepoint, do a different highlight reconstruction or clipping - there’s no magic around.
Without access to the image it’s just speculating:

  • try set highlight reconstruction to reconstruct in Lch (maybe color, but if the reds are clipping frst, this doesn’t help)
  • if that doesnt work then use clipping - but then you lose information
  • for some cameras the raw whitepoint might be to high (i fond this with my old Canon 7d) so reducing it might help.

A lot of stuff Rawtherapee might do under the hood - in darktable it’s up to you to decide what and how much information you’re going to ditch :wink:

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Indeed, it does.

I can’t look anywhere anymore without mentally assessing the dynamic range. IMHO this is where it starts, and where is the most “bang-for-the-buck” in the quality of the result rendition. Exposure that doesn’t clip highlights provides the best starting point for this; all the curving and tone-mapping in post is just to accommodate the initial data…

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This has nothing to do with linear or scene-referred. The old white balance doesn’t match the brain + eyes adaptation to different illuminants, since it massages sensor RGB. The chromatic adaptation works in an RGB space modelling the retina cone response, so it’s closer to perceptual response.

Magenta highlights are linked to clipped highlights reconstruction, which is not the scope of the color calibration.

The scope of color calibration is to fix the remaining mismatches between recorded data and perceptual response to the scene after the raw white-balance (old module) and input color profiles have been applied. So, you can see it as an input profile tuner.

Once the mistmatches have been fixed, you can choose to export that high-fidelity image as-is, or apply artistic corrections that will not only behave better but give more reproduceable results when you copy-paste them between images.

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Link to raw play:

Magenta highlights are linked to clipped highlights reconstruction.
Ah, i see. “Overexposing sunsets” is kind of relic from analog times, I guess.

OK, so I had misundertood.

I had understood that if you were using the new “modern” approach, color calibration would completly substitute the white balance old module.

But I understand well, white balance is still needed and prior to color calibration, at least to do camera RGB balancing (apply the correct coefficients to your camera in a standard situation).
Then you can use the color calibration to adjust colors and adapt them to different light situations or even different lights in the scene.

Well, I have to take it easy and try it in my photos, I usually do not need a precise reproduction of colors, but I like them to seem natural.

I can see now that when you use the modern adjustment, the white balance changes from “as shot” to a neutral profile.

My photo gets quite yellowish, but I can return it to a similar look changing the illuminant to “as in original shot” (the selected illuminant was Daylight).
In this case the Bradford lineal and CAT16 give me similar results.

Why “as shot” illuminant is not taken by default?
For a newbye, I think it would give him results more close to execpet, similar to the OOC jpeg.

It just dawned on me, this is the same class of logic I invoked when I made camera profiles from unwhitebalanced Colorchecker shots. All other processing equal, the renditions produced with these profiles had more-saturated color, for lack of a better description, than the renditions with the regular profiles and multiplier white balance. LittleCMS uses a Bradford chromatic transform by default.

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I actually get ‘as shot’ by default, at least the values are the same (in this case, 4755 K). Default:
image
Changing to ‘as shot’ (note the same colour temperature and the classification as ‘daylight’):
image

The image colours don’t change, either. This is with NEF (Nikon) and RW2 (Panasonic) files.

here :

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It is. The default parameters, put in the module when you open it, are the settings defined by your camera and put in EXIF. The real “as shot” option is a redundancy that helps you create presets that will read, at runtime, the actual image EXIF instead of storing the WB of the image on which you made the preset (so it’s a dynamic preset).

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Thank you all. The error is located behind the camera. Blown reds result in magenta shifting.

Thank you.

But I don’t have as shot by default, I have Day light as default, and the image is quite yellow.
When I change the illuminant to “as shot in camera” I get it the right color.

I have to retest it with new images (I have tested it with images that were already edited, changing the workflow to modern and resetting their history to get the new workflow with white balance and camera calibration).

@anon41087856 reading is not enough, you need to understand what you are reading to be effective.

I had misunderstood several things in what I had read till now.
Thanks to this thread I think I have a better understanding of what camera calbration does and how to use it to make simple white balance and color interpretation.

Now it is time to re read the documentation slowly as you say with a new perspective.

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I had similar problems in sky with zones that are partially blown, with cyan tones.

I think the problem is earlier in the pipeline, as was said here.
There is a light reconstruction algorithm just after white balance.
It clips blown channes by default.

Better results can be get sometimes with color reconstruction or reconstruct LCh (which makes them white).

Some times you can recover llights using exposure and underexposing a bit, as the lights are not really blown in the raw.

Adjusting filmic parameters can help too.
But I don’t know exactly how each parameter in filmic affects blown lights yet.

Reversely, in the shot I posted any highlight reconstruction leads to magenta colors. In the next sunrise-/set photos I will expose to right regarding the sun and see what happens (e.g. shadows).

So it might be a bug in the initialization of the module, maybe the EXIF are not available at the time of init or something. What if you reset the module ? It should give the same settings as “as shot in camera”.

OK, I will double check it to see if after resetting I have the same temperature as when I use as shot for the illuminant.

Well, think about the camera for a bit. Setting the WB to Daylight just forces use of the daylight multipliers. If the camera was set to Auto WB, the as-shot multipliers will probably be a best-effort assessment of the actual scene with regard to WB.

I pretty much keep my camera WB mode on Auto, so I can take advantage of the camera assessment of the scene for my initial batch proofs.

Me too, I use auto WB almost allways, as I shoot raw and allways process afterwards.
Camera makes a good guess most of the times, and when not I change it later witout loss of quality. Any way I most of the times am going to make some color adjustment to my taste, I do not need fidelity in colors most of the times, just a good aproximation.

But when I use the modern workflow and reset the history of a file I had already in darktable (I don’t have recent new files to test) white balance is set to neutral and color calibration is set Day light with a temperature that is not coincidente to what is set in the camera.
The photo seems too yellow.

Let mi put an example of a photo without processing, just reseted history with modern workflow active:
This is the settings under white balance
image

This under color balance:
image

As you can see it adjusts the illuminant to Day light and the temperature to a different one that is used in camera (Aureliene has explained that themperatures do not coincide).

And this is the result a bit yellowish

After changing color calibration and selecting illuminant as shot, the colors are more natural and similar to the old workflow without color calibration (and white balance adjusted to as shot).

If I reset the module setting I get the same result with the temperature set to the same value to “as shot” (well not exactly the same it seems there are 2 K diference).

image

This the result

If I understood well what aureliene has explained, when you import the image (or reset the history) it should use the illuminant taken from the exif in camera, and both images should be the same (if you have not adjusted something).

And for the sake of completion, here is the same image with the old workflow (heritage), the whitte balance and the result (white balance is quite more warm as shot in camera).
image

You can see these ultimate results are quite similar.

Temperatures of the images are all different.