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# RGB::fromWaveLength

Get the RGB color of monochromatic light

### Use only in the MuPAD Notebook Interface.

This functionality does not run in MATLAB.

## Syntax

```RGB::fromWaveLength(λ, <γ>)
```

## Description

RGB::fromWaveLength( λ ) returns an approximative RGB specification for light of wavelength λnm.

Light consists of photons, each of which has a distinct wavelength. These different wavelengths cause color perception. RGB::fromWaveLength calculates an RGB triple corresponding to a given wave length.

Different displays show the same RGB color in slightly different ways. For this reason, the so-called "gamma correction" has been invented. RGB::fromWaveLength accepts a second argument, for fine-tuning the assumed gamma correction that enters the calculation.

Color perception depends on a number of factors, including individual differences. Therefore, such a calculation can only return an approximation. RGB::fromWaveLength uses the model published by Dan Bruton for the conversion.

For wavelengths outside the visible spectrum (which ranges from 380 nm to 780 nm), RGB::fromWaveLength returns black.

## Examples

### Example 1

White light, when sent through a prism, is split into the commonly known spectrum, because the prism refracts different wavelengths differently. This spectrum can easily be reproduced by RGB::fromWaveLength:

```plot(plot::Raster([[RGB::fromWaveLength(i) \$ i=380..780]]),
Scaling = Unconstrained, Height = 20)```

### Example 2

Bruton's conversion model looks like this:

```plotfunc2d(
plot::Raster([[RGB::fromWaveLength(i) \$ i = 380..780]],
x = 380..780, y = -0.2..0),
(x -> RGB::fromWaveLength(x)[i]) \$ i = 1..3,
x = 380..780,
Colors = [RGB::Red, RGB::Green, RGB::Blue],
LegendVisible = FALSE,
XTicksNumber = Low,
Scaling = Unconstrained,
Axes = Automatic)```

## Parameters

 λ The wavelength: a real-valued constant (interpreted as nanometers) or a length expression γ The "gamma correcture" for the display, defaults to 0.8

## Return Values

RGB color: a list of three floating-point values