You could try this
Put the images into a folder named Images on the Desktop
Sub EveryPresentationInFolder()' Performs some operation on every presentation file in a folder adapted from PPTools.com
Dim sFolder As String ' Full path to folder we'll examine
Dim sFileSpec As String ' Filespec, e.g. *.PNG
Dim sFileName As String ' Name of a file in the folder
Dim oPres As Presentation
Dim lngSld As Long
Dim rayNum() As String
Dim sngL As Single
Dim sngT As Single
Dim sngW As Single
Dim opic As Shape
sFolder = Environ("USERPROFILE") & "\Desktop\Images\" ' This is Images on Desktop
sFileSpec = "*.PNG"
Set oPres = ActivePresentation
sngL = 0
sngT = 0.6 * 28.3465
sngW = oPres.PageSetup.SlideWidth
sFileName = Dir$(sFolder & sFileSpec)
While sFileName <> ""
Debug.Print sFileName
rayNum = Split(sFileName, ".")
lngSld = CLng(rayNum(0))
If lngSld <= oPres.Slides.Count Then
Set opic = oPres.Slides(lngSld).Shapes.AddPicture(FileName:=sFolder & sFileName, _
LinkToFile:=False, _
SaveWithDocument:=True, _
Left:=sngL, _
Top:=sngT, _
Width:=sngW)
opic.LockAspectRatio = True
opic.Width = sngW
opic.Left = 0
opic.Top = sngT
opic.ZOrder (msoSendToBack)
End If
sFileName = Dir()
Wend
End Sub
You will have problems if the image ratio is very different to the slide or the images are not all PNG's
WORK ON A COPY