compress pictures

Gurus,

I have searched far and wide for a vba code to compress all pictures in a worksheet. Below is the best I could find, however, I am not sure what the code is doing or what the settings are? Does anyone have any idea? The options I would like is to:

1) compress all pictures
2) delete cropped areas of pictures
3) use default resolution

Sub test()

    Dim wsh As Worksheet

    Set wsh = Worksheets("Sheet1")
    wsh.Activate
    wsh.Shapes(1).Select

    SendKeys "%e", True
    SendKeys "~", True
    Application.CommandBars.ExecuteMso "PicturesCompress"
End Sub

I have also found another line which replaced

 SendKeys "%e", True

with

SendKeys "%w", True

Not sure what the difference is.

TIA,
Tim