As per
DNG spec, there are a few tags that define the conversion of the raw data from camera space to XYZ space.
Here they are:
CalibrationIlluminant1
CalibrationIlluminant2
ColorMatrix1
ColorMatrix2
CameraCalibration1
CameraCalibration2
ForwardMatrix1
ForwardMatrix2
ReductionMatrix1
ReductionMatrix2
AnalogBalance
ProfileHueSatMapDims
ProfileHueSatMapData1
ProfileHueSatMapData2
DNG Converter doesn't produce Reduction Matrices for canon raw files, so these can probably be ignored. AnalogBalance seems to always be 1 1 1.
Everything else is used by ACR when developing a Canon raw file turned into .dng (by Adobe DNG Converter)
Tags with 1 and 2 at the end correspond to the respective calibration illuminant. While using both the illuminants is optional, these allow for a more precise mapping at different white balance settings.
Here is what DNG Converter always outputs from a Canon 5d mark 3 .cr2 raw file:
Calibration Illuminant 1 : Standard Light A
Calibration Illuminant 2 : D65
Color Matrix 1 : 0.7234 -0.1413 -0.06 -0.3631 1.115 0.285 -0.0382 0.1335 0.6437
Color Matrix 2 : 0.6722 -0.0635 -0.0963 -0.4287 1.246 0.2028 -0.0908 0.2162 0.5668
Camera Calibration 1 : 0.9923 0 0 0 1 0 0 0 0.9843
Camera Calibration 2 : 0.9923 0 0 0 1 0 0 0 0.9843
Forward Matrix 1 : 0.7868 0.0092 0.1683 0.2291 0.8615 -0.0906 0.0027 -0.4752 1.2976
Forward Matrix 2 : 0.7637 0.0805 0.1201 0.2649 0.9179 -0.1828 0.0137 -0.2456 1.057
These are model based, except Camera Calibration, which in theory is individual camera specific. I guess the way to check if CameraCalibration is indeed individual camera specific is to compare with the same tag from other 5dm3 cameras. CameraCalibration has a noticeable effect on the resulting image (well, with these particular values, at least), slightly boosting reds and blues.
And here is what comes from raw2dng:
Calibration Illuminant 1 : Standard Light A
Calibration Illuminant 2 : D65
Color Matrix 1 : 0.6722 -0.0635 -0.0963 -0.4287 1.246 0.2028 -0.0908 0.2162 0.5668
Note how the matrix used is actually the matrix for the D65 illuminant (as specified by DNG Converter) but here corresponding to Standard Light A (tungsten) instead. The second illuminant will be ignored by raw processors because there are no matching matrix tags. As a result the raw processor only uses this matrix instead of interpolating between the two based on chosen WB.
ForwardMatrix1 and ForwardMatrix2 are applied by both ACR and Resolve but appear to have a minor effect. I actually expected Resolve to ignore them, as they are absent in BMCC files, but they are applied.
ProfileHueSatMapDims, ProfileHueSatMapData1, ProfileHueSatMapData2 define hue/saturation/value mapping tables which are applied last, and actually have significant impact on the final image in some parts of the color space. These are read and applied by ACR, but ignored by Resolve. Note that these aren't exactly small and add around 64KB to the file. These are binary tags and can be copied from an existing DNG Converter created .dng still onto the video .dng files (by ACR users, anyway).
So I'd suggest adding to the EXIF:
CalibrationIlluminant1
CalibrationIlluminant2
ColorMatrix1
ColorMatrix2
ForwardMatrix1
ForwardMatrix2
CameraCalibration1 and CameraCalibration2 should be added only if they turn out to be model specific and not individual camera specific. In the latter case probably an option to specify them explicitly would be nice? Handling the HSV table tags is probably an overkill (and increases size significantly), and it is easy to add with ExifTool anyway.
[Note that the values listed above only apply to 5dm3.]
The above doesn't touch on the black/white levels based on white balance, which is another story.
Hope this helps.
