I am using CAT (16) adaptation as a basis for color calibration on raw images. On nearly all of my images the CCT is shown as ‘(invalid)’ prior to making any adjustment. I then set the illuminate to ‘daylight’ since my material is generally outside. After using the pick and selecting the entire image the CCT again returns to ‘invalid’
The results look fine but the ‘invalid’ signal tells me that something is incorrect.
Should I be selecting daylight? If I select ‘black-body’ or ‘detect from surfaces’ the invalid indicator remains and there is no change to the final CCT value.
From the manual
When the CCT is followed by (invalid), this means that the CCT figure is meaningless and wrong, because we are too far from either a daylight or a black body light spectrum. In this case, you are advised to use the custom illuminant. The chromatic adaptation will still perform as expected (see the note below), so the (invalid) tag only means that the current illuminant color is not accurately tied to the displayed CCT. This tag is nothing to be concerned about – it is merely there to tell you to stay away from the daylight and planckian illuminants because they will not behave as you might expect.
Depending on the camera, it’s possible that you are seeing the issue described in the ‘caveats’ section of the dev version manual. I don’t think the fix described there would work in 3.4.1, only in the current dev version or 3.6 when it’s released.
I think my Olympus might be affected but I’m not really sure yet, need to experiment more.
In general the numbers are meaningless very often…remember this is a color correction from the standard WB set to D65 and after the application of the input profile so in very loose terms its an accurate way to achieve WB but the numbers will not be the “true” K WB that you might be seeking…around min 23 here it is explained in detail…https://www.youtube.com/watch?v=U4CEN0JPcoM