I am finding the color calibration module seldom gives good results for any automatic effort the AI detect modes and the detect from are eyedropper included) at white balance. I am constantly resorting to switching it back to “as shot in camera”. The majority of my stuff is shot outside under natural light. Sky/cloud/backlight colour has been particularly annoying of late.
Having read the manual, I feel I understand what the options try to do. I didn’t want to switch the modern processing back to legacy without trying a bit harder with the color calibration module.
So, I would welcome tips and suggestions on this new (to me at least) way of obtaining good white balance using modern color calibration.
In daylight and even into twilight, without mixed light temps, the automatic calibration has been pretty good. 1 in 20 times I click the dropper which selects the whole image, forces a recompute, and then its fine.
Perhaps some sample images would be more useful than talking about things abstractly.
However, the automatic calbration you are using, according to how I read the manual, is using the “as shot in camera” value.
Even if the default calibration looks OK, if you click on the eyedropper, or try the AI modes, it most often gives bad looking results. So, I just set it back to"as shot in camera". I suppose I should just hit the reset and let it redo the initial calculation.
I am using the default modern scene workflow. White balance set to D65 (the lightbulb) and Color Calinration’s CAT to auto or just one click on the eye dropper without adjusting the eye dropper selection.
You still need to do the dropper on something neutral…if you don’t is will use the data of the whole image and so of course it will be wrong…as shot is fine for me and usually matches as shot legacy…from there its your job find a neutral spot for adjustment or to make an edit that pleases your eye if there is a cast …no???
I’m not sure that I’ve ever fully understood this part of the cc module - but aside from the eyedropper it’s got those automatic modes, (AI) detect from image edges, or surfaces.
With me… they (or at least one of them) always seem to end up at what seems like a default of 5002K (IIRC). It’s never bothered me as I usually want to set it manually anyway (or use the camera setting.
To be clear, I’m not saying there’s a problem, more just that I’m not sure whether I’m missing something, and if so, maybe I’m not the only one
Another thought: I think the eyedropper just samples the average of the area selected? So as @priort mentioned when using it one has to select a neutral bit on the photo… or hope that the average of the whole image is neutral.
Using a selected CAT… CC is using the data from the input profile and d65 reference values to attempt to manipulate color as described here… with the potential to mask that effect.
I think calling spot wb auto wb is a misnomer. If you have an image with strong cast from foliage etc selecting the whole image source for neutral will usually over correct in some manner. I find if you have to resort to this as you don’t have a good wb or a neutral object then just switch to custom after doing the “auto” wb on the whole image and slowly drop the saturation. I find this the most usual case as it will usually be over corrected with this method to some extent. If on the off chance it is not corrected enough then bump the saturation slider in CC custom … to add more correction… you could tweak the hue if needed but its usually in the ballpark such that you just need to tweak how much is applied…
Yes, I do that fairly often, and that bit all works as expected… for me
Do you have any experience with the ‘AI’ modes? I thought the idea was that they should work on the whole image with less intervention, but after a quick refresh of the manual I’m not quite sure.
Thanks for the link - I had a look but will need to read it properly later.
Really I think they were experiment calculations/modes by AP. I think even he said at some point they are not that reliable…but I would have to go and find that to be certain…
I don’t know what you expect those automatic modes to do, but all they can try is to get the selected area as close to neutral (gray) as possible.
On a lot of images, using the whole image to get the white balance works fine.
On images like the one above, with one dominant colour, less so, as the algo will try to get rid of the excess green. Exactly what it is supposed to do…
@n01r : The text from the manual you quoted is the “default” setting, i.e. what’s used when you do nothing but activating the module. A bit lower (on the page you quoted from) it goes on to say:
CAT tab workflow
The default illuminant and color space used by the chromatic adaptation are initialised from the Exif metadata of the RAW file. There are four options available in the CAT tab to set these parameters manually:
Use the color picker (to the right of the color patch) to select a neutral color from the image or, if one is unavailable, select the entire image. In this case, the algorithm finds the average color within the chosen area and sets that color as the illuminant. This method relies on the “gray-world” assumption, which predicts that the average color of a natural scene will be neutral. This method will not work for artificial scenes, for example those with painted surfaces.
(…)
@priort 's method of dropping the saturation of the illuminant after using the eyedropper usually works for me as well. And trying to pick a patch you want to be neutral in your image also helps.
there’s no AI in at all - it’s just evaluation the Color mood of the selected area. So if the available colors are well spread over the spectrum it might give good results, if you select neutral grey areas it gives good results. In other cases it might identify an illumination resulting from the most widely uses colors.
The camera white balance can be better because camera manufactures spends a lot of effort in their automatic exposure evaluation as well as in their image evaluation to optimise whitebalancing.
The (AI) options are not real artificial intelligence, but it was shorter than spelling “optimization by machine-learning” in the list, and AI is all the rage now so pretty much anything a bit advanced qualifies for that name these days. They perform an auto-detection of the best illuminant in image.
Aurélien has said (in one of his videos, or written somewhere) that a result close to 5000 K usually means the ‘AI’ method failed to determine the illuminant (set the correct white balance).
For me I find that with most of my shots the camera has done a good job with white balance or selecting from the drop down options in white balance module provides a good white balance. I feel the color calibration module just adds extra work to my processing with little or no reward. So I use legacy rather than modern processing. I am willing to stand corrected on this if someone can explain the advantage of adding extra work to my processing.
However, I like that I can do multiple instances of color balance which I can not with white balance alone. This helps in mixed lighting. I also like the spot color mapping options.
Yes, I wonder what it does differently. I would have thought it could only do something like the eyedropper does, and only over the whole picture, but still it gets it far closer to being correct.
Starting to feel similarly. The color calibration module does all sorts of stuff, but I feel, for WB, it isn’t actually helping much.
I have not actually switched back to legacy, but that is an option. I just feel I might get left behind as darktable moves on.
