Hi all,

Sorry it isn’t really about ACES but I was watching some videos about color spaces and came to this interesting talk. "RGB to XYZ: The Science and History of Color" by John Austin - YouTube

He says that it’s usually best to create a black and white image in CIE-Lab because it gives the most perceptually consistent result w.r.t how we perceive given original colors’ brightness.

That made me want to learn and experiment upon which I first discovered that you get the worst results when doing this in log especially with very saturated(bright?) colors.

Pipe: RWG/Log3g10 → RGC → conversions → Resolve saturation slider → ACES rec.709 Out

Original

RWG/Log3g10 desat

ACEScct desat

ACEScg desat

RWG/Linear desat

Clearly doing this in linear gives a more sensible result to my eye. Different color spaces still can give very different results.

Now back to the main question. Doing this in CIE-Lab… how would I go about this? I work in Resolve and I’m not sure how to apply the correct math to do this operation. The normal Saturation slider will result in something quite funky. I’m thinking it has to do with the fact that a, b are balances between colors instead of single vectors so to speak? So making them equal still returns colors?

Would love to know some more about this.