I am using this code to take screenshots on a production machine and save them to a folder. each file is about 400 kb in size, and I do not really need good resolution and quality. How can I half the resolution and reduce the jpg quality to save space?

Private Sub TakeScreenShot()

    Dim screenSize As Size = New Size(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
    Dim screenGrab As New Bitmap(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
    Dim g As Graphics = Graphics.FromImage(screenGrab)
    g.CopyFromScreen(New Point(0, 0), New Point(0, 0), screenSize)

    screenGrab.Save("screenshots\test.jpg", Imaging.ImageFormat.Jpeg)

End Sub

CodePudding user response：

Following this MSDN article, you can set 50% quality like this

Private Sub TakeScreenShot()
    Dim screenSize As Size = New Size(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
    Dim screenGrab As New Bitmap(My.Computer.Screen.Bounds.Width, My.Computer.Screen.Bounds.Height)
    Dim g As Graphics = Graphics.FromImage(screenGrab)
    g.CopyFromScreen(New Point(0, 0), New Point(0, 0), screenSize)
    Dim jpgEncoder As System.Drawing.Imaging.ImageCodecInfo = GetEncoder(System.Drawing.Imaging.ImageFormat.Jpeg)
    Dim myEncoder As System.Drawing.Imaging.Encoder = System.Drawing.Imaging.Encoder.Quality
    Dim myEncoderParameters As New Imaging.EncoderParameters(1)
    Dim myEncoderParameter As New System.Drawing.Imaging.EncoderParameter(myEncoder, 50&)
    myEncoderParameters.Param(0) = myEncoderParameter
    screenGrab.Save("screenshots\test.jpg", jpgEncoder, myEncoderParameters)
End Sub

Public Function GetEncoder(ByVal format As ImageFormat) As ImageCodecInfo
    Dim codecs As ImageCodecInfo() = ImageCodecInfo.GetImageDecoders()
    Dim codec As ImageCodecInfo
    For Each codec In codecs
        If codec.FormatID = format.Guid Then
            Return codec
        End If
    Next codec
    Return Nothing
End Function