Perceptual quantizer

The perceptual quantizer (PQ), published by SMPTE as SMPTE ST 2084,[1] is a transfer function that allows for HDR display by replacing the gamma curve used in SDR.

[2][3][4][5] It is capable of representing luminance level up to 10000 cd/m2 (nits) and down to 0.0001 nits.

[2] It was developed by Dolby[6] and standardized in 2014 by SMPTE[1] and also in 2016 by ITU in Rec.

2100.

[7][8] ITU specifies the use of PQ or HLG as transfer functions for HDR-TV.

[7] PQ is the basis of HDR video formats (such as Dolby Vision,[2][9] HDR10[10] and HDR10+[11]) and is also used for HDR still picture formats.

[12][13] PQ is not backward compatible with the BT.1886 EOTF (i.e. the gamma curve of SDR), while HLG is compatible.

PQ is a non-linear transfer function based on the human visual perception of banding and is able to produce no visible banding in 12 bits.

[14] A power function (used as EOTFs in standard dynamic range applications) extended to 10000 cd/m2 would have required 15 bits.

[14] The PQ EOTF (electro-optical transfer function) is as follows:[7][15]

=

max [ (

The PQ inverse EOTF is as follows: