private void ChosseBtn_Click(object sender, EventArgs e)
        {
            using (OpenFileDialog dlg = new OpenFileDialog())
            {
                dlg.Title = "Open Image";
                dlg.Filter = "bmp files (*.bmp)|*.bmp";

                if (dlg.ShowDialog() == DialogResult.OK)
                {
                    var colorCodes = this.GetColorCodes(dlg.FileName);
                    var str = string.Join(Environment.NewLine,
                    colorCodes.Select<int[], string>(line => string.Join(" ", line.Select<int, string>(code => string.Format("{0:X8}", code))))); // string.Format("{0:X6}", code & 0x00FFFFFF) if you want RRGGBB format
                    textBox1.Text = str; // requires textBox1.Multiline = true, better have monospaced font
                }
            }
        }
        private int[][] GetColorCodes(string path)
        {
            var bitmap = new Bitmap(path);
            return Enumerable.Range(0, bitmap.Height)
                             .Select<int, int[]>(y => Enumerable.Range(0, bitmap.Width)
                             .Select<int, int>(x => bitmap.GetPixel(x, y).ToArgb()).ToArray()).ToArray();
        }