private void PictureBox1_MouseUp(object sender, MouseEventArgs e)
{
using (var bmp = new Bitmap(PictureBox1.Image.Width, PictureBox1.Image.Height))
{
PictureBox1.DrawToBitmap(bmp, PictureBox1.ClientRectangle);
var color = bmp.GetPixel(e.X, e.Y);
var red = color.R;
var green = color.G;
var blue = color.B;
MessageBox.Show(Convert.ToString(red + " " + green + " " + blue + ""));
}
}