I was afraid it might not be right on all images - that style was a purely ‘eyeball’ effort. Looked good on the one, but I’ve found before that that’s not a good guide.
I’m certainly not an expert, but this page in manual might be of help darktable 4.4 user manual - color calibration
I think your results seem ok, although not 100% sure about the max. It will be a certain color patch that ill be less accurate than the others I think.
Thanks, the manuals says that
ΔE < 2.3 means that the average observer will not be able to tell the difference between the expected reference color and the obtained color. This is a satisfactory result.
so I am good.
Now that this is resolved, back to taking photos 
@TonyBarrett, if you still use a GX9, you may be interested in the correction I attach above. Please let me know how it works for you.
Try running DT chart and see what you think about the result… The funny thing is when I play with these things ie icc or CC corrections and watch the vectorscope there are changes but many appear to be subtle wrt change in acutal hue… Looking at the Gx9 on the vectorscope… cyan is rotated massively to blue and magenta a lot towards red… yellow a bit towards red and green towards yellow… red and blue seem bang on and the jpg is not markedly different wrt hue angles so its not undergoing a massive change there… It may be that you cant do something like you see in Davinci and line up these primaries on the vectorscope or maybe there is some nuance to the vectorscope presentation but for sure this shift or alignment of magenta and cyan would impact the nature of red the camera shows…
You can see it here with the as shot wb
Setting it to the camera specific daylight from the meta shift WB quite a bit but actually aligns the hues a bit better swinging yellow green and magenta…
In any case to me that pattern on the vector scope is the GX9 color signature of sorts and I would that thought that calibrations might have move the needle more that it seems to …
They get marked so you can see the ones that are less accurate or in the “fail” zone…
Well really you are not. The approach just has to be a bit different… Now you would select none and then use autopresets to apply whatever combination of modules you want. If the module does something on startup then you just add reset to the preset so that it applies in its default state…so you could do this will filmic as well for example or others that make small adjustments when they are first initialized…
Both darktable and RawTherapee have an black level offset, compared to Exif. For RawTherapee it is Exif (128) + 16. darktable has it locked to 143. Increasing this to 144 or 145 makes the image less red.
If you want to calculate your black level GitHub - lightful/hraw: Hacker's toolkit for image sensor characterisation and a black raw file should work. See here for more about black level and hraw Measure black and white levels?
In the sample 1Ds, like your GX9, doesn’t have any hidden black fields to analyze. Therefore a picture with lens cap on should work.
If you have a calibrated monitor, it’s easy to create custom WB coefficients. It’s probably explained in the manual, but if not, AP covers it here:
The DataColor Spyder Checkr Photo can often be found for quite cheap, and DT added support in the last release.
So this is the sort of thing you get from DT-chart…
I made it simple… I exported the images attached above as needed to pfm files with as shot WB no CC.
I ran the process matching to the jpg…
Open the raw using only as shot WB and EV to set white patch to 92 using the LAB picker…
Then applied the style… It really has two main components a tone curve and the clut module.
To my eye it does a really nice job of the blues to spread them out and lighten them… I think red looks better as well…
So this style could be dissected a bit and used as a color adjustment without the tone curve if one objects…using other modules for the purpose… You could try to make it using CC in the source images as well… Its a nice tool but older so people don’t use it
This is the same but matched against the colorchart values not the jpg…
GX9ColorChecker.dtstyle (5.0 KB)
Thanks! I tried that and
→ ./hraw rgbstats -i P1002224_0.pgm [58061bd]
width;height;X;Y;;;;;;;;;;;;;
2600;1952;0;0;;;;;;;;;;;;;
R mean;R min;R max;R stdev;G1 mean;G1 min;G1 max;G1 stdev;G2 mean;G2 min;G2 max;G2 stdev;B mean;B min;B max;B stdev;
142.394;131;152;1.36246;142.827;134;189;1.30148;142.884;134;230;1.29193;142.454;132;177;1.35626;
so maybe the 143 (the default in Darktable at the moment) is not that unreasonable?
It seems good. You can verify so that it is the same at high ISO also.