Please forgive me if I misunderstand the question, but I think A1ex's question 1) asks about the relationship between the various arrays of "WB RGGB" (e.g. four ints) values and the actual values to scale each color channel by to white balance?
If so, then marekk is right but has the values inverted. The ratio of the WB RGGB integers is the same as what should be used for the color channel scaling values. Thus, as in marekk's example and setting the green multiplier to be 1 (since only the ratio of them matters), we get
WB RGGB Levels As Shot : 1967 1024 1024 1796
becomes
wbgain_r = 1967/1024 = 1.9209
wbgain_g = 1
wbgain_b = 1796/1024 = 1.7539
These directly applied to the color channels will neutralize the color of the light, but not correct for being in the camera's color space.
The second question is much more complicated, and I'm not sure if there's any standard way to do it. It might be different for every camera, requiring some calibration. If the "WB RGGB Levels" EXIF tag or the "Red/Blue Multiplier" tags are available those should be used instead of the Kelvin. Are there cameras where only Kelvin is available?
If so, then marekk is right but has the values inverted. The ratio of the WB RGGB integers is the same as what should be used for the color channel scaling values. Thus, as in marekk's example and setting the green multiplier to be 1 (since only the ratio of them matters), we get
WB RGGB Levels As Shot : 1967 1024 1024 1796
becomes
wbgain_r = 1967/1024 = 1.9209
wbgain_g = 1
wbgain_b = 1796/1024 = 1.7539
These directly applied to the color channels will neutralize the color of the light, but not correct for being in the camera's color space.
The second question is much more complicated, and I'm not sure if there's any standard way to do it. It might be different for every camera, requiring some calibration. If the "WB RGGB Levels" EXIF tag or the "Red/Blue Multiplier" tags are available those should be used instead of the Kelvin. Are there cameras where only Kelvin is available?