Darktable should read the D65 Color Matrix from DNGs when possible
Currently Darktable doesn't read the D65 ColorMatrix from DNG files. Often this means people are stuck with the linear RGB color profile applied as input profile. With the end result being very dull files.
For a few camera's Leica M9/X1/X2 and some Ricoh models, I manually extracted those matrices and put them into our adobe_coeff's file, as a stop-gap measure.
So ideally we'd read the D65 matrix, with the following logic:
1. Is the RAW a DNG?
2. If yes, does the DNG contain a CalibrationIlluminant with type 21 (=D65)
3. If yes, load the corresponding ColorMatrix and show it in 'colorin' as "dng embedded matrix" and default to this (even if we have other matrices available).
Some sample EXIF:
Exif.Image.CalibrationIlluminant1 Short 1 17
Exif.Image.CalibrationIlluminant2 Short 1 21
Exif.Image.ColorMatrix1 SRational 9 8197/10000 -3931/10000 2593/10000 -2921/10000 9004/10000 4621/10000 -504/10000 832/10000 7365/10000
Exif.Image.ColorMatrix2 SRational 9 8235/10000 -2659/10000 -965/10000 -2426/10000 10625/10000 2078/10000 -686/10000 1246/10000 5898/10000