PM Variable for Tint Portion of White Balance

[Robert Edwards Media]

Photo Mechanic 2024.10 build 7907 (424a632) | Windows 10 Pro 22H2 build 19045.5131 | Lenovo ThinkPad X1 Carbon Gen6 | Nikon Z9 and D5 14-bit NEF files

Question: Is there a PM variable for the tint portion of white balance?

Example: A raw file is captured with White Balance 5000K +6.0 Magenta.  The {kelvin} variable shows the 5000K part.  Is there a variable to show the green/magenta (Tint) part (+6.0, in this example).

[Kirk Baker]

Robert,

Photo Mechanic 2024.10 build 7907 (424a632) | Windows 10 Pro 22H2 build 19045.5131 | Lenovo ThinkPad X1 Carbon Gen6 | Nikon Z9 and D5 14-bit NEF files

Question: Is there a PM variable for the tint portion of white balance?

Example: A raw file is captured with White Balance 5000K +6.0 Magenta.  The {kelvin} variable shows the 5000K part.  Is there a variable to show the green/magenta (Tint) part (+6.0, in this example).

No, there is no such variable.  If you run your image through ExifTool, does it report that information?

-Kirk

[Robert Edwards Media]

Hi Kirk, I don't see an EXIF field for 'Tint', at least in the Nikon Z9 RAW.  'Color Temperature Auto' stores the kelvin value.

I attached a short list of EXIF fields that I *think* relate to color ("EXIF_Color_Fields.PNG").  Could Tint it be derived from, say, the delta between Blue & Red Balance in line #116 "WB RB Levels"? 

[Kirk Baker]

Robert,

Hi Kirk, I don't see an EXIF field for 'Tint', at least in the Nikon Z9 RAW.  'Color Temperature Auto' stores the kelvin value.

I attached a short list of EXIF fields that I *think* relate to color ("EXIF_Color_Fields.PNG").  Could Tint it be derived from, say, the delta between Blue & Red Balance in line #116 "WB RB Levels"?

Hard to say.  Neither multiplying or adding those two values produces a number anywhere close to 6.  This could be Nikon maker note data.  Have you looked in that section of the ExifTool output?

-Kirk

[Bob M]

For more than you ever want to know about tint, see: https://www.strollswithmydog.com/white-point-cct-tint/

The key takeaway is

"‘Tint’ is what many cameras and raw converters call some derivation of Duv.  For instance the aforementioned D5300 illuminant has a CCT of 5299.9K and a Duv of 0.003266.  Adobe calls Tint 3000 times Duv,[3] so it would show as 9.8 in the white balance section of Adobe Camera Raw or Lightroom.  Unfortunately the definition of Tint is not standardized and every manufacturer chooses to present Duv in their own way.'

Tint is an ill defined term. What counts are the three rgb multipliers.

[Robert Edwards Media]

Hi Bob and Kirk, fascinating material, thank you for sharing.  So the 50,000-foot view is:

1) Tint is not stored in EXIF as a discrete value, unlike the Kelvin value for WB.
2) Tint is a calculated value using several data points, including RGB multipliers that estimate the image's white point. 
3) Tint calculation algorithms vary by manufacturer (camera systems, image editing software, etc.) 
4) The math is well above my pay grade.

Due to these complexities, Tint understandably cannot be displayed within Photo Mechanic.