Something like this maybe:
Sub CropPic()
Dim oshp As Shape
Dim osld As Slide
For Each osld In ActivePresentation.Slides
For Each oshp In osld.Shapes
If isPic(oshp) Then
With oshp
.PictureFormat.CropLeft = 0
.PictureFormat.CropTop = 0
.PictureFormat.CropRight = 0
.PictureFormat.CropBottom = 30
.LockAspectRatio = False
.Height = 265
End With
End If
Next oshp
Next osld
End Sub
Function isPic(oshp As Shape) As Boolean
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
End Function
Be aware that setting LockAspectRatio to False may distort images.