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 # SpectralSpectrumChange 

 Last update: 17.07.2025 

## Description

Allows you to apply a spectrum to a source on spectral map.

Returns 0 if:

- the map is not a spectral map.
- the index of the source does not exist.
- the path does not exist or no path defined or wrong path.

## Syntax

*object*.SpectralSpectrumChange(int *iSource*, BSTR *bstrFileName*)

- *object*: Virtual Photometric Lab or Virtual Human Vision Lab object
- *iSource*: index of the source to activate
- *bstrFileName*: filename string including path
    
    When bstrFileName does not exist, the spectrum is deactivated on the layer.

## Example

```
Sub main()
 Dim MyFolder As String
MyFolder = "PathWorkSpeace"
 Dim XmpViewer As Object
Set XmpViewer = CreateObject("XmpViewer.Application")
 Dim MyFile As String
MyFile = "NameOfXmpMap.xmp"
 retval = XmpViewer.OpenFile(MyFolder & MyFile)
 retval = XmpViewer.Show(1)
 Dim NbLayer As Integer
NbLayer = XmpViewer.ExtendedGetNbSource()
 Dim MySpectrumFile As String
MySpectrumFile = "NameOfSpectrumFile.spectrum"
 For i = 0 To NbLayer - 1
retval = XmpViewer.SpectralSpectrumChange(i, MyFolder & MySpectrumFile)
Next i
 For i = 0 To NbLayer - 1
retval = XmpViewer.SpectralSpectrumChange(i)
Next i
 End Sub


```