Nuke expression reminder to self. Linear to HyperLogGamma and back again.
r = current channel (r, g, b) a1 = 0.17883277 b1 = 0.28466892 c1 = 0.55991073
To HLG
r > 1 ? a1 * log ((r) - b1) + c1 : 0.5 * sqrt(r
From HLG
r > 0.5 ? exp( (r - c1) / a1) + b1 : 4 * pow(r,2)