PQ / ST.2084

PQ (Perceptual Quantization, standardized as SMPTE ST.2084, announced by Dolby in 2014) is an HDR transfer function that is absolute: a code value maps to a fixed brightness in nits, full stop. Grade to 1000 nits in PQ and “1000 nits” means the same light level on every correctly set-up display — which is why PQ largely solves the “looks different on every screen” problem and why it underpins HDR10 and Dolby Vision. It’s the replacement for gamma 2.4 in the HDR world, paired with the wide Rec.2020 gamut inside the Rec.2100 container. Contrast it with HLG, which is relative and backward-compatible. PQ dominates cinematic streaming delivery.

First used in: 3.6 · HDR grading