# LuminanceMetric enum

Namespace: [Grasshopper2.Extensions](https://developer.rhino3d.com/api/gh2/namespace/grasshopper2.extensions.md) · Assembly: [Grasshopper2](https://developer.rhino3d.com/api/gh2/assembly/grasshopper2.md)

```cs
public enum LuminanceMetric
```

Enumerates the available metrics for luminance computations. When in doubt, use [LuminanceMetric.YCbCrGammaAdjusted](https://developer.rhino3d.com/api/gh2/type/grasshopper2.extensions.luminancemetric.md).

## Values

| Name | Value | Description |
| --- | --- | --- |
| Average | 100 | Compute the straight-up average of red, green and blue. This approach is exceedingly naïve and does not yield good luminance values. |
| Desaturate | 101 | Compute the luminance by removing the saturation. This method results in softer luminance mapping and only takes the highest and lowest RGB values into account. |
| YCbCrPhotometric | 102 | Standard ITU BT.601 luma coefficients on RGB channels. This is a very common luminance metric used in software everywhere. |
| HdtvPhotometric | 103 | Standard ITU BT.709 luma coefficients on RGB channels. This metric was designed for HDTV and probably yields worse results on most computer screens than PhotometricYCbCr. |
| YCbCrGammaAdjusted | 104 | Standard ITU BT.601 luma coefficients on gamma adjusted RGB channels. This metric yields results in close agreement with human perception. |
| HdtvGammaAdjusted | 105 | Standard ITU BT.709 luma coefficients on gamma adjusted RGB channels. This metric was designed for HDTV and probably yields worse results on most computer screens than GammaAdjustedYCbCr. |
| YCbCrPerceived | 106 | Standard ITU BT.601 luma coefficients on non-linear RGB channels. This metric yields the best results on most computer screens. |
| HdtvPerceived | 107 | Standard ITU BT.709 luma coefficients on non-linear RGB channels. This metric was designed for HDTV and probably yields worse results on most computer screens than PerceivedYCbCr. |