Still new to RawDigger and most of the concepts herein...
One of the striking features to me in the Histograms is the presence of an "EV scale".
I understand that EV stands for "Exposure Value", a legacy photographic term and related to scene Luminance.
What strikes me most is this "EV=0" reference?
Page 26 of 85 in the User Guide has a section of the "EV grid" where it is explained that "EV0" is automatically calculated from the image statistics: "Located at 3 stops lower than the maximum pixel value, rounded to the nearest power of 2".
Silly me! I thought, naively, that this "EV0" was an absolute "Reference point"?
And was under the impression that EV0 *had* to correspond to 18% gray reflectance?
For example, in my ColorChecker NEF, the N5 patch (18% gray) has these RGB values :
R: 869 of Max 4845
G: 1603 of Max 10279
B: 1138 of Max 7456
G2: 1691 of Max 7623
Silly me! I just noticed that there is place where EV0 is shown numerically, and that's 2048.
I can see that EV0 is indeed sitting at 2048 on the histogram for all four channels.
But 2048 does not correspond to any of the N5 RGB values... Sigh...
More reading and scratching my head...
"Three stops lower than the maximum pixel value"?
I can see, on the Histogram, that in the case of my NIkon D810, the Max value is 16,000.
My Nikon D810 RAW is supposed to be 14bit so 16,384 value, maximum.
So could 2048 be 18% gray?
Please forgive my ignorance but I was under the impression that 18% gray would be an "invariant"?
I need to better understand this in the context of my particular camera response...