The perceptual quantizer (PQ), published by
SMPTE
The Society of Motion Picture and Television Engineers (SMPTE) (, rarely ), founded in 1916 as the Society of Motion Picture Engineers or SMPE, is a global professional association of engineers, technologists, and executives working in the m ...
as SMPTE ST 2084,
is a
transfer function
In engineering, a transfer function (also known as system function or network function) of a system, sub-system, or component is a function (mathematics), mathematical function that mathematical model, theoretically models the system's output for ...
that allows for
HDR display by replacing the
gamma curve
Gamma correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in video or still image systems. Gamma correction is, in the simplest cases, defined by the following power-law expression:
: V_\text = ...
used in
SDR.
It is capable of representing luminance level up to 10000
cd/m2 (nits) and down to 0.0001 nits.
It has been developed by
Dolby
Dolby Laboratories, Inc. (often shortened to Dolby Labs and known simply as Dolby) is an American company specializing in audio noise reduction, audio encoding/compression, spatial audio, and HDR imaging. Dolby licenses its technologies to ...
and standardized in 2014 by
SMPTE
The Society of Motion Picture and Television Engineers (SMPTE) (, rarely ), founded in 1916 as the Society of Motion Picture Engineers or SMPE, is a global professional association of engineers, technologists, and executives working in the m ...
and also in 2016 by
ITU
The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...
in
Rec. 2100
ITU-R Recommendation BT.2100, more commonly known by the abbreviations Rec. 2100 or BT.2100, introduced high-dynamic-range television (HDR-TV) by recommending the use of the perceptual quantizer (PQ) or hybrid log–gamma (HLG) transfer func ...
.
ITU specifies the use of PQ or
HLG as transfer functions for HDR-TV.
PQ is the basis of HDR video formats (such as
Dolby Vision
Dolby Vision is a set of technologies developed by Dolby Laboratories for high dynamic range (HDR) video. It covers content creation, distribution, and playback. It includes dynamic metadata that are used to adjust and optimize each frame of the ...
,
HDR10
HDR10 Media Profile, more commonly known as HDR10, is an open high-dynamic-range video (HDR) standard announced on 27 August 2015 by the Consumer Technology Association. It is the most widespread of the HDR formats.
HDR10 is not backward compati ...
and
HDR10+
HDR10+ is a high dynamic range (HDR) video technology that adds dynamic metadata to HDR10 source files. The dynamic metadata are used to adjust and optimize each frame of the HDR video to the consumer display's capabilities in a way based on the ...
) and is also used for HDR still picture formats.
PQ is not backward compatible with the
BT.1886 EOTF This article is about the transfer functions used in pictures and videos and describing the relationship between electrical signal, scene light and displayed light.
Definition
The opto-electronic transfer function (OETF) is the transfer functi ...
(i.e. the
gamma curve
Gamma correction or gamma is a nonlinear operation used to encode and decode luminance or tristimulus values in video or still image systems. Gamma correction is, in the simplest cases, defined by the following power-law expression:
: V_\text = ...
of
SDR), while
HLG is compatible.
PQ is a non-linear
transfer function
In engineering, a transfer function (also known as system function or network function) of a system, sub-system, or component is a function (mathematics), mathematical function that mathematical model, theoretically models the system's output for ...
based on the human visual perception of
banding and is able to produce no visible banding in 12 bits.
A power function (used as EOTFs in standard dynamic range applications) extended to 10000
cd/m2 would have required 15 bits.
Technical details
The PQ EOTF (
electro-optical transfer function This article is about the transfer functions used in pictures and videos and describing the relationship between electrical signal, scene light and displayed light.
Definition
The opto-electronic transfer function (OETF) is the transfer function ...
) is as follows:
The PQ inverse EOTF is as follows:
where
*
is the non-linear signal value, in the range