/// <summary>
        /// constructor imBarcodeReaderForm()
        /// </summary>
        public imBarcodeReaderForm()
        {
            InitializeComponent();

            camDevices = new CameraDevices();

            decodingThread = new Thread(DecodeBarcode);
            decodingThread.Start();
            btnThreshold.BackColor = Color.Red;
            pictureBox1.Paint += pictureBox1_Paint;
            resultRectPen = new Pen(Color.Green, 10);
        }
        /// <summary>
        /// constructor imBarcodeReaderForm()
        /// </summary>
        public imBarcodeReaderForm()
        {
            InitializeComponent();

            camDevices = new CameraDevices();

            decodingThread = new Thread(DecodeBarcode);
            decodingThread.Start();
            btnThreshold.BackColor = Color.Red;
            pictureBox1.Paint     += pictureBox1_Paint;
            resultRectPen          = new Pen(Color.Green, 10);
        }