You wanted a raw from R6III

[Heddesdorfer]

You can download it here:

https://drive.google.com/file/d/1hYfUhD9NDjyV55v5szPpe0k4Y_KZGBqN/view?usp=sharing

[Bitpainter75]

Thank you, that file settled the question. The magenta cast is not a bug in FerrumPix, and it is
also not the missing colour matrix I first suspected. It is the black point.

What the file says when LibRaw 0.22.2 reads it, the same version FerrumPix ships:

• The R6 Mark III is not in LibRaw's camera table. It lists R5, R5 C, R5 Mark II, R6, R6 Mark II
  and R50, but not the Mark III.
• The colour matrix is there and looks plausible, so that part is fine.
• The black point LibRaw reports is 0. Measured against the optically black border of your file it
  is about 2074.

That closes the chain. Every pixel keeps a pedestal of roughly 2074, and the camera white balance
(R 1.87, G 1.00, B 1.85) multiplies that pedestal along with the image. Red and blue get lifted by
almost a factor of two, green not at all, so the whole frame turns pink.

Cross-checked with the very same library: dcraw_emu -w produces the magenta image,
dcraw_emu -w -k 2048 produces normal colours from the same file, white blossom and green foliage
just like the camera preview.

Where that leaves us: LibRaw's C interface has no function to set the black point and no way to
read the raw values back, so we cannot correct this in our own decode path without depending on the
internal layout of its structures, which would break silently on the next LibRaw update. The proper
fix is a LibRaw release that adds the camera.

What works for you today: run the CR3 through a DNG converter that writes the black level itself,
then FerrumPix opens the DNG with correct colours. The embedded camera preview is also correct, so
browsing and rating the files works, only the raw development does not.

One more thing from your report: the bundled camera and lens collection did not know the R6 Mark III
either, which is why there was no crop factor and no lens correction match. That collection has been
refreshed and now contains the camera.

[Bitpainter75]

Please try the new 0.9.53-2 for your Canon R6 Mark III

[Heddesdorfer]

Works! Great!
Just a remark: The first few seconds after clicking on ANPASSEN nothing happened, then this was displayed:

looks a bit strange. Meanwhile I changed behaviour to open with editor and it looks normal.