Assuming your pictures are inserted in-line, try:
Code:
Sub Demo()
Dim iShp As InlineShape
For Each iShp In ActiveDocument.Tables(1).Range.InlineShapes
With iShp
.LockAspectRatio = False
.Height = InchesToPoints(3.8)
.Width = InchesToPoints(2.75)
End With
Next
End Sub
Although this will do as you ask, I'm not sure disabling the LockAspectRatio is a good idea. That might result in some images getting messed about.