Pour garder les proportions et que l'image fit dans la case (sans déborder) :
Sub Macro4()
Dim a As Double, b As Double
Set pic = ActiveSheet.Pictures.Insert("C:\Picture 3.jpg" )
a = pic.Height / pic.Width
b = Cells(2, 2).Height / Cells(2, 2).Width
pic.Top = Cells(2, 2).Top
pic.Left = Cells(2, 2).Left
If b < a Then
pic.Height = Cells(2, 2).Height
pic.Width = Cells(2, 2).Width * b / a
Else
pic.Width = Cells(2, 2).Width
pic.Height = Cells(2, 2).Height * a / b
End If
End Sub