Bonjour,
En VBA avec le programme par défaut (avec API Windows) :
Declare Function ShellExecute _
Lib "shell32.dll" _
Alias "ShellExecuteA" ( _
ByVal hWnd As Long, _
ByVal lpszOp As String, _
ByVal lpszFile As String, _
ByVal lpszParams As String, _
ByVal lpszDir As String, _
ByVal FsShowCmd As Long) As Long
Declare Function FindWindow _
Lib "user32" _
Alias "FindWindowA" ( _
ByVal lpClassName As String, _
ByVal lpWindowName As String) As Long
Sub Test()
Dim Fichier As String
Fichier = "D:\Dossier\Sous Dossier\Ma photo.jpg"
ShellExecute FindWindow("", Application.Caption), "Open", Fichier, "", "", 1
End Sub