Digital Light & Color

A couple questions about Colour Balancing an image.

I ran the same image through two processes. The image (a headshot of a Palomino horse - fairly light toned) started with a Levels and Colour dynamic range of 11.8 to 96.5.

First process - Straight to Colour Balance, with Auto White and Black Balances enabled. In the Levels and Colour tool, the dark end was now 1.2 on the DR scale and white was 100, so I clicked on Full Range to make it 0 and 100.

Second process (all tools reset) - First did Full Range in Levels and Colour, followed by the Colour Balance Tool, again with Auto White and Black enabled.

I expected that both images would end up with the same result, however they are noticeably different (put through "Blink" the one which went straight to the Colour Balance had a greener tint - or conversely I guess the other looked more pink). Funny things is, running them through Composite > Absolute Difference, the resultant image is all black. After I first experienced this, and just prior to posting this message, I happened to read Charles2 post and thinking my eyes were also playing tricks on me when I did the side by side comparison, I went back and re-did it with Blink so they were on top of each other.

So, if the results are meant to be the way this turned out, which is the suggested best method? To my eyes, the Second process seems to be more visually pleasing but that doesn't mean it's the most accurate??

Thanks,

Marv

The two processes are slightly different so I am not surprised the results are also slightly different. Off the top of my head, here is what I would expect. If you do a Full Range first, then Auto Black does nothing in Color Balance since blacks are already black. If you Color Balance first, it will remove any cast from the shadows as well as the highlights and then Full Range will stretch the dynamic range afterwards. There may also be some differences since Color Balance works in RGB and Levels and Color works in HSV or HSL, so the order of operations by make a small difference. My inclination would be to color balance first, possibly omitting the auto black unless you have a color cast in the shadows, but if doing it in the other order produces a more pleasing result, by all means feel free to do so.