This is something I can’t figure out, I shoot in raw dng format but every time I import it into darktable it has a ugly yellow filter, i’m new to darktable so the settings should be on default. This doesn’t happen in photoshop & lightroom and it’s not how the image looks at default. I shoot with a sigma sd quattro w/ a Sigma 17-50mm f/2.8 EX DC OS lens if any of that is useful information.
Pretty much no Foss software supports the foeveon sensor so far as I know.
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Such a shame, love the camera. Thank you for your comment!
Still holding out hope for a fix/update
I would be interested in getting the original image file to see if any programs can handle it. I wonder if converting it in Adobe DNG converter would give a useable file for editing in DT?
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Other programs can handle it just not darktable, additionally using adobe DNG converter is unnecessary… using a dng converter, to convert an already dng file into yet again, a dng.
Sorry. Just trying to help. I presume supplying a sample image to the right location may improve the chances of getting darktable’s support for your camera. Putting your DNG file through Adobe’s DNG converter may seem strange but it may be a solution if you want to use DT. If you are happy to continue using Adobe’s PS and LR then all is good for you.
Don’t apologize for anything you’re a great help! 
I’ve tried it regardless and sadly still hasn’t worked. 
I do prefer DT since i’m trying to have a free and open source workflow and want to avoid using adobe as much as possible. Especially since I prefer darktable over lightroom.
Why not put in a feature request for camera support for your file type. The link below will get you to the right place for a feature request.
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Thank you!
This is a known issue for Sigma DNGs: Sigma SD & DP cameras: White Balance and/or color calibration are off for DNGs · Issue #16586 · darktable-org/darktable · GitHub
See also this workaround, or the one suggested in the manual: darktable 4.6 user manual - color calibration
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I think you should be able to convert it to a linear DNG that can be used in most any software. That should be seen as a lossy process though, as it will become linear RGB through demosaicing.
Iirc, the colour channels in the foveon sensor cover very wide frequency bands, causing a lot of “crosstalk” between channels. Saftware tailored to bayer sensors is not set up to deal with that (each channel is treated as a “pure” color, more or less).
Perhaps the channel mixer might help? But the processing probably requires some (proprietary) tricks, which aren’t available to FOSS programmers…
The DNGs from Sigmas are already “linear raw”, and are fine, there’s just something about the color calibration and white balance modules that’s weird, as mentioned:
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That cast looks like white balance wasn’t applied at all. My Nikon D7000 raws, with the whitebalance tool turned off, look like this:
White balance isn’t just about the illumination at the scene. Most cameras have different transmission characteristics in each of the three channels, which is simply dependent on the bayer filter materials. Applying white balance, where the goal is to make a known white patch look white, takes care of both.
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Fantastic! Tried the fix (the one suggested on github) makes the problem better but color temperature looks cooler, so not completely fixed but probably easier to edit.
If you could share a file then probably a few of us could have a look at work arounds. Since you are getting a better result but color is still a little cool, then maybe RGB curves might allow you to tweak the color to the desired tone.
RGB Primaries would likely be better, but we would indeed need a sample file to know for sure.
Speaking of RGB curves, you can get a similar result by using tone eq with one of the color channel blend modes.
There is a Sigma sd Quattro DNG sample on RPU I have used for the screenshot above.
Would it be alright if I send a link of a google drive? Because the website says the file is too big to upload. 
You could send a link. I am surprised the file is too big. How big is it? Sorry for the late reply but motorcycle vs car on Wednesday coming home from work and I lost.