Ted all I can think of is that the sample area is not as uniform in color as you would like.
Co-incidentally I did something similar yesterday with my Nikon and Sony cameras and after correction with the WB picker on a gray card included in the shots, all images looked as good as identical to me.
Dave
Had me worried there, so I opened the area where I clicked and found the mean hue (before balancing) to be 194 degrees (HSV model) but, fortunately, with a standard deviation (SD) of only two degrees of hue. Not a whole lot, so the uniformity was OK, I reckon.
Incidentally, a portion of a black railing in the Bridget shot has an SD of 13 degrees of hue - a lot - whereas her left mammary area has only an SD of a mere 1 degree of hue.
Of course, SD isn't really a measure of hue uniformity, some will say. So maybe SD/mean where 0=perfect ...
Good to hear. We now need to hear from a Canonista ...Co-incidentally I did something similar yesterday with my Nikon and Sony cameras and after correction with the WB picker on a gray card included in the shots, all images looked as good as identical to me.
Last edited by xpatUSA; 7th September 2019 at 12:12 AM.
Being bored and after having a weird WB experience last week I set up an experiment to see if WB could be equalised easily on a number of shots taken at various in camera WB settings on my D800.
Scenario;
Some garishly coloured small items including a Grey card set up and shot using manual flash bounced from a white ceiling with no ambient (that could vary) affecting the scene.
Four shots taken, Auto WB, Daylight setting, 2500K (camera min) and 10000K Camera max).
Opened in ACR, all images selected and four RGB test point targets placed, including one in the Grey Card area. This ensures they are in identical positions on each image.
The WB Picker was then used on each individual image at the target on the grey card. Note, the accuracy here is not 100%, but pretty close.
With all images now 'corrected' I could not detect any variation in colours by eye, but there were very slight variations in RGB values such as;
0,152,112 - 0,152,116 - 0,152,115 - 0,151,115
241,92,0 - 240,91,0 - 241,90,0 - 242,90,0
Conclusion - As far as I'm concerned when shooting in RAW (which is always) I'll never be concerned that I may have inadvertently adjusted the WB setting entirely wrong for the situation I'm shooting as it can be corrected good enough for me in post
Last edited by xpatUSA; 7th September 2019 at 03:05 PM.
Grahame - this very much reflects my experience as well and the values that effectively identical; most people are never going to notice the difference between 0, 152, 116 and 0, 151, 115.
Back in my "wet" colour darkroom days, the finest adjustment I could make was with an 05 CC (Colour Correction) filter (although the dichroic colour heads claimed an accuracy down to 01 CC). This was considered more than "good enough".
That being said, in most cases my eyes, coupled with chromatic adaptation will continue to be the weakest part of my colour workflow.