When the user changes the selected compression level, the program saves an image with the desired compression. It then displays the file's size and displays the file so you can see the effect of the compression. This lets you easily judge the tradeoff between compression and image quality.

Private Sub cbCI_SelectedIndexChanged(ByVal sender As _
    Object, ByVal e As System.EventArgs) Handles _
    cbCI.SelectedIndexChanged
    'Release loaded file
    If Not (pbPic.Image Is Nothing) Then
        pbPic.Image.Dispose()
        pbPic.Image = Nothing
    End If
    pbPic.Image = Image.FromFile(Application.StartupPath & _
        "\temp100.jpg")
    SaveJPGWithCompressionSetting(pbPic.Image, _
        Application.StartupPath & "\temp.jpg", _
        Val(cbCI.Text))
    pbPic.Image = Image.FromFile(Application.StartupPath & _
        "\temp.jpg")
    lblCI.Text = cbCI.Text
    Dim FileSize As Long
    Dim suffit As String
    FileSize = FileLen(Application.StartupPath & _
        "\temp.jpg")
    If FileSize < 1000 Then
        suffit = " Bytes"
        GoTo showit
    End If
    If FileSize > 1000000 Then
        FileSize = Int(FileSize / 1000000)
        suffit = " Mb"
        GoTo showit
    Else
        FileSize = Int(FileSize / 1000)
        suffit = " Kb"
    End If
showit: lblTemp.Text = FileSize & suffit

End Sub

Private Sub SaveJPGWithCompressionSetting(ByVal image As _
    Image, ByVal szFileName As String, ByVal lCompression _
    As Long)
    Dim eps As EncoderParameters = New EncoderParameters(1)
    eps.Param(0) = New EncoderParameter(Encoder.Quality, _
        lCompression)
    Dim ici As ImageCodecInfo = GetEncoderInfo("image/jpeg")
    image.Save(szFileName, ici, eps)
End Sub

Private Function GetEncoderInfo(ByVal mimeType As String) _
    As ImageCodecInfo
    Dim j As Integer
    Dim encoders As ImageCodecInfo()
    encoders = ImageCodecInfo.GetImageEncoders()
    For j = 0 To encoders.Length
        If encoders(j).MimeType = mimeType Then
            Return encoders(j)
        End If
    Next j
    Return Nothing
End Function