Good question. I put mine after, but as I said in the other thread, I just found something that seemed to work and moved on. Essentially a fix for a slightly skewed WB, and which wasn’t always required. And now that I have custom WB coefficients, I find that I don’t need it - minor adjustments in CAT are usually enough.
If you do a full profiling, the matrix is applied in the same instance as the CAT I believe. So that seems like a valid option. Putting it before the CAT instance may or may not screw things up, I really have no idea. Putting it after does mean, in my experience, that it essentially becomes the WB adjustment and any changes in CAT should be avoided as they may make everything look wrong.
Its my understanding at least when you do this using the automated routine created by AP its part of the CAT tab and it results in a tweak to color using color channel tweaks in the channel mixer tabs while taking into account the input profile , wb , and the cat settings to derive those adjustments. I know that this needs a color checker. But since that is how it is applied when using that method I would think that it would be fine to simply add it in there.
@Tamas_Papp Have you tried simply grabbing the test shots for your camera from imaging resources and running the automated procedure and just see if it might be generally applicable or useful…
Try disabling the color calibration module entirely and keep using the white balance module only. As far as my experience with the GX80 and the G9 cameras goes, the color calibration module always comes with a cast, and sometimes quite an odd one.
Also, newer RW2 files enable the ability to tweak the daylight setting to your likings, like make it look warmer or colder without having to fiddle with the temperature and tint sliders.
Thanks, that worked great. Specifically, setting white balance to “as shot” removes the cast. I can still use color calibration for minor corrections.
I am wondering if there is a way to set this up automatically for new images, with a setting or a preset. I recall auto-apply chromatic adaptation: legacy in the processing tab of the preferences, but I can no longer find it. Now white balance gives me the camera reference for new images.
Setting to none or display-referred will give you WB with As Shot. That’s what I am currently doing for the same reason. Keep in mind, this will affect the default blend colorspace of the modules (they will prefer display referred).
Auto-Presets will not work for the WB module in your case.
Aargh. Then the least-tedious solution would be manually changing WB to “as shot” for each image. I wonder if I can use LUA scripts for this (probably not).
I am surprised that auto-detection in color calibration gives me better results for some images with WB “as shot”. But it is image-dependent, occasionally OK, sometimes not.
I think that the best and most general solution will be a matrix, as suggested by @Donatzsky, because WB only has 2 degrees of freedom, while the matrix has 3x3-1=8. After all, this is about the sensor, not white balance.
It is my impression that this issue is highly relevant in general for a lot of cameras. Cf this topic, where unfortunately I was not able to obtain a practical solution:
Again, I am fine with getting a color chart and doing the legwork, but it is unclear what I would do with images afterwards to get the color matrix into Darktable. I am under the impression that they are no longer added.
There is the initial workflow script, somewhere here in the forum. Doesn’t fit my workflow, but it is generally really usefull, I think.
Yeah, that’s what I have done too. Got a (actually multiple) color chart and created an icc input profile which I’m happy with (This is something I would recommend in general, as the colors are better represented as with the generic matrix).
The WB module issue is still there though. I need/want to use the WB in as shot mode (because otherwise I would need to determine better D65 values) and so I keep the pixel workflow setting at none.
Umm… what effect does this have? I wasn’t aware of that… I currently use ‘none’ too, as I also prefer the legacy WB, although I love CC for more creative adjustments, but I wasn’t aware of any side-effects.
It would be nice if someone who knows can enlighten us… I will try the manual although I expect you’ve looked there already.
As far workflow goes I love scene referred as far as the rest of it goes, it’s just I don’t really like the complication of color calibration and the well known caveats with it, as, for me, usually, it doesn’t give any advantage.
I’ve just looked, and on my system, DT 4.4, with workflow set to none, different modules have different default blend colorspaces - color balance rgb is display, while diffuse and sharpen is scene…
I should check this experimentally, but maybe this is actually unrelated to the workflow setting in preferences and instead simply down to which module one looks at?
I kind of agree, but it doesn’t really bother me as I’m quite happy with the ‘none’ option as I like swapping tonemappers, and so on… and that gives the old ‘as shot’ setting for WB. Apart from possible issues as discussed just above…
Ok, regarding CB… the color workspace is defaults to RGB (display) with ‘None’ and to RGB (scene) with ‘Scene referred (filmic)’.
Yeah, as I said, might be completly FUD from my side. But I would prefer to use the RGB (scene) setting, which I don’t get per default with ‘None’. I really don’t want to annoy anyone, just stating my opinion. The solution last time I mentioned this was, maybe to create presets (which save the color workspace setting). But its really hard to do this consistently (looking at my ~50 presets over all modules).
That may be, but I don’t think the casts that people notice for various cameras are a white balance problem, and consequently white balance is not the right tool to fix them.
To summarize,
all cameras need a color correction matrix,
adding one requires specialized equipment (a chart) and knowledge (to process this chart)
lacking that, people can figure out a preset by eyeballing photos for their camera, but it is unclear
a. how much these generalize to other light circumstances,
b. if not, how to automate the process,
c. where to put them in the pipeline.
Again, I am aware that I could just get a color chart for best results. But I am not after that level of fidelity because I am a hobbyist. I just want to get a linear mapping (a matrix) that gives a reasonable starting point.
I will now experiment and will probably find a preset that removes the cast. But the broader issue is that I see no systematic way to share these presets and avoid duplicating the work.
I would add that the default dt matrix isn’t just one matrix for all cameras - I’m not familiar with it, but it seems to be quite accurate for many cameras - My Nikons for example are pretty close to my own matrix profiles, when using the defaults.
While I think of it, the other thing that needs doing if you want color calibration to be as accurate as possible is the custom white balance reference value… it’s detailed in the manual. Involves taking a photo of a 6500K light source - like a calibrated computer screen.
I’m wondering what would it take to add Adobe profiles support to DT? They are a great help for me in RawTherapee and ART. I can get good colors and tonal range right away without having to tinker with numerous modules.
While I think of it, the other thing that needs doing if you want color calibration to be as accurate as possible is the custom white balance reference value… it’s detailed in the manual. Involves taking a photo of a 6500K light source - like a calibrated computer screen.