Is the vibrance slider in ACR and Lightroom doing essentially the same thing as manually shifting the tops and bottoms of the A and B curves in LAB color?
It seems similar, but is the math actually the same?
No. And the math is very, very different.
What you are describing affects saturation, sort of.
Vibrance is similar to saturation, but has different curves and the high and low ends, and affects skin tones differently.
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