# PQ

> Perceptual Quantizer (PQ), also known as SMPTE ST 2084 transfer function, used for High Dynamic Range (HDR) displays.

## Definition

* **Type:** Field
* **Namespace:** [UnityEngine](/engine/6000.7/script-reference/unityengine.md)
* **Assembly:** UnityEngine.CoreModule

```csharp
PQ = 2
```

### Remarks

The Perceptual Quantizer (PQ) transfer function is a newer version of a traditional gamma curve used in Standard Dynamic Range (SDR) displays.

Unlike the gamma curve, which is a simple power-law function, the PQ curve is designed to better align with the non-linear way the human eye perceives luminance.

The function is designed for High Dynamic Range (HDR) displays, enabling a more accurate and perceptually uniform representation of brightness across a wide range of luminance levels, up to 10,000 nits.

For more information, refer to [SMPTE reference document for ST 2084](https://pub.smpte.org/latest/st2084/st2084-2014.pdf) and [Dolby's Reference Level Guidelines For PQ (BT.2100)](https://professional.dolby.com/siteassets/pdfs/operational-guidelines-for-pq.pdf).

Unity uses this EOTF when the [ColorGamut](/engine/6000.7/script-reference/unityengine/colorgamut.md) of the display is [ColorGamut.HDR10](/engine/6000.7/script-reference/unityengine/colorgamut/hdr10.md) or [ColorGamut.DolbyHDR](/engine/6000.7/script-reference/unityengine/colorgamut/dolbyhdr.md).