PQ ST 2084 Is Not Log

In Debunking “HDR”, Steve Yedlin says, “it doesn’t matter what the curve shape is as long as you know what the curve shape is.”

Yet he has no idea what PQ is, who developed it, or why. 

He mislabels PQ as logarithmic:

“And by the way the shape of this curve this logarithmic curve used in Rec. 2100 is called PQ. It’s called the PQ curve.”

In fact, it is a perceptual quantizer based on the Barten contrast sensitivity model, developed by Dolby to replace SDR gamma, and published by SMPTE as ST 2084 in 2014. 

The shape is crucial. A log EOTF wastes code values where they aren’t needed. PQ uses them efficiently by tracking the Barten Ramp across the HDR luminance range.

Yedlin is essentially telling his followers to disregard the origin of PQ, to ignore its purpose, and to accept that it is logarithmic when it’s not.  

That is not how scientific inquiry works. 

That is not how a masterclass in color pipelines is supposed to be taught. 

If you’re going to ‘debunk’ HDR, the least that is expected of you is to have a basic understanding of the standards you’re critiquing. 

Yedlin has publicly confessed that he does not. 

That alone invalidates his entire argument.