Why very high white balance temperature for some cameras?


#1

Starting from the camera setting for white balance, RT gives some files very high temps, 40000K or 50000K. The same file opened in other raw developers might come out at 8000K. Casual observation suggests this happens when the sky is blown, for example. A change from Camera WB to Auto will sometimes bring the temp to a reasonable value.

Why is RT so different with some cameras? I’ve seen this on Sony and on Leica SL. Very high temps are not meaningful to me and therefore difficult to adjust to taste.


(Morgan Hardwood) #2

Please upload a sample file.


#3

Here is a sample at “only” 30856K, tint 0.970. By comparison, in a trial version of Silkypix Developer 8, the camera setting is given as 4998K, tint 3 magenta. The shot has blown sky (deliberately allowed), but other shots with no blown pixels may still come out at tens of thousands degrees Kelvin. Sometimes RT Auto white balance computes a more typical value, sometimes it too says tens of thousands degrees.

leaves_temp_example.DNG (42.3 MB)


(Ilias Giarimis) #4

Usually RT shows abnormal WB values for raws of non fully supported cameras (missing colormatrix data) or cameras with different than the expected colormatrix2 at D65 illumination in DNG exif.

This last is what happens with this DNG sample … it reports a D50 colormatrix2 … RT supposes a D65 and the calculations fail. If we change the matrix to D65 (copy from Adobe dcp or just convert the DNG with DNG converter the values calculated are temp: 5222 tint: 1.030


#5

Thanks for a clear, concise explanation and a good workaround!

Is it appropriate that RT check for the type of colormatrix and calculate accordingly? Should I post the suggestion somewhere? (No more question - I wrote up the issue.)