This might need a bit of work from you but should get you started.
Sub exporter()
Dim opic As Shape
Dim L As Long
Dim x As Long
Dim osld As Slide
On Error Resume Next
For Each osld In ActivePresentation.Slides
For L = osld.Shapes.Count To 1 Step -1
If isPic(osld.Shapes(L)) Then
If x < 64 Then x = 64
Select Case x
Case 64
MkDir (Environ("USERPROFILE") & "\Desktop\Images\")
Call osld.Shapes(L).Export(Environ("USERPROFILE") & "\Desktop\Images\" & _
osld.SlideIndex & ".png", ppShapeFormatPNG)
x = x + 1
Case Else
MkDir (Environ("USERPROFILE") & "\Desktop\Images\" & UCase(Chr(x)) & "\")
Call osld.Shapes(L).Export(Environ("USERPROFILE") & "\Desktop\Images\" & UCase(Chr(x)) & _
"\" & osld.SlideIndex & ".png", ppShapeFormatPNG)
x = x + 1
End Select
End If
Next L
x = 0
Next osld
End Sub
Function isPic(osld As Slide)
Dim oshp As Shape
For Each oshp In osld.Shapes
If oshp.Type = msoPicture Then
isPic = True
Exit Function
End If
If oshp.Type = msoPlaceholder Then
If oshp.PlaceholderFormat.ContainedType = msoPicture Then
isPic = True
Exit Function
End If
End If
Next oshp
End Function